Mike, Paul, and Colleen help an owner raise his oil temperatures, explain the rules around ELT battery replacements, debate the merits of a tuned exhaust, and help an owner whose airplane won't quit. Email [email protected] for your chance to get on the show. Join the world's largest aviation community at www.aopa.org/join Full notes below: Chris has a Super Decathlon with CHTs as low as 270 degrees and oil temperature around 150. Even with the oil cooler covered during winter, it still doesn?t get hot enough. Mike said they like to see oil temperature up to 200 degrees if possible. Chris can check the vernitherm by putting it in boiling water to see when it actuates. Mike said the oil temperature gauge is typically reading at the coolest part of the process, and the oil may climb 40 degrees higher. Curtis just wanted to change his ELT battery. His mechanic sent it away to a service center. He received an invoice with three options, none of which included replacing the battery. His standby current apparently tested high. Unfortunately Curtis was in an unusual situation with a foreign-produced part. There are two answers, Mike said. There?s the answer where you feel like you have to follow the manual, and one if you follow the regulations. The manual says the battery must be replaced by a Part 145 shop, but the regs allow the owner to do it under preventative maintenance. Mike contends that since the battery replacement section of the manual is not an airworthiness limitation, Curtis can just brush it off. Pierre-Louis and his club in Switzerland have a tuned exhaust system on their airplane and while he is seeing some benefits in terms of fuel burn and climb rate, he is most interested in the smoothness of the engine. He said it feels like having a 6-cylinder engine and he?s wondering if tuned exhaust systems offer better engine longevity. Colleen thinks it?s possible the engine is actually working harder (more horsepower), so she guesses that the engine longevity would be reduced. Mike said he disagrees because the engine isn't producing more power, its power is being used more efficiently. Paul suggests that less vibration is ultimately better for the engine. Frank has a Rockwell Commander 112 and when he shuts it down it sometimes diesels, or won?t entirely quit. Typically it only happens in the summer after a flight when it?s warm. Mike and Paul said the only way that happens is if the mixture doesn?t fully shut off the fuel supply. Mike said the mixture cable to the carb is the first place to check. Colleen suggests that it could be a leaking primer as well. Mike recommends fault isolating it by disconnecting the primer to see if it resolves. 

This episode Mike, Paul, and Colleen debunk myths, describe valves that are eligible for lapping, and cover the basics of the red box and leaning. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Maciej is a new private pilot who is questioning some operational procedures he was taught. He was taught not to put fuel back into the tanks after sumping it, and he thinks if you sample it and it?s clean, why not put it back? The hosts agree that if the sample is clean, put it back. He also wonders about oversquare on the impact on the propeller. A ground school he took says that it is too hard on the propeller to run it at low rpm and high power. Mike questions the validity of this, and Paul said to go ask the source because it doesn't seem right to him either. George has an airplane with some valve issues. Five of his cylinders have varying levels of green on them. He was told that four could probably be lapped, but the fifth has to be pulled. He?s wondering if green on a valve, which is later lapped clean, weakens or otherwise compromises the valve. Most of the green you see is green deposits, according to Mike. In early days of borescoping cylinders, the colors on the face of the valve were all we had to go on. Now, when we can position the camera between the valve and the seat, and can see if there?s erosion. If there isn?t erosion, it?s a good candidate for lapping. Mike said as long as the valve isn?t a train wreck that it?s worth lapping. Most people don?t do it aggressively enough. Doug is an instructor who was flying a Cessna 182 with a client and the owner didn?t want him to lean, even though they were flying higher than 8,000 feet. Finally he convinced the owner that it was ok to lean a little to smooth out the engine. Apparently the owner was worried about the red box. Since the goal is to stay below 400 degrees on the cylinder head temperatures, Mike thinks it?s hard to get 182 cylinders that hot at altitude, and below 400 degrees there is no red box. Paul makes the point that because power output at 8,000 feet is below 65 percent, you can?t hurt the engine by leaning.

With everything going electronic in the cockpit, will owner-produced parts become a thing of the past? Plus, Mike, Paul, and Colleen talk about their least favorite magnetos, deferring maintenance, and more. Email [email protected] for a chance to be on the show. Join the world's largest community of aviators at aopa.org/join Full notes below: Justin owns a Columbia 400 and he?s wondering if he can make owners-produced parts for some of his electronics. The hosts agree that this is a problem with aircraft maintenance. Because it?s difficult to show original design criteria for electronics, it?s hard to prove the part meets the original standards. There are a lot of things you can?t easily duplicate, Paul says. Ben is a new aircraft owner and a lot of the previous squawks were deferred. He wants to know what he can do to help keep the airplane in top form before the next annual. Most of what Ben mentions is preventative maintenance and relatively minor. Paul said to focus on corrosion issues, including at the forward and aft wing attachments. Those are steel attached to aluminum. If you catch it early you can avoid future maintenance issues. Paul recommends using FAR Part 43 Appendix D as a guide for the what Ben should watch for. Colleen said to focus on things that would be expensive later. There?s a lubrication chart in the service manual, and Paul said to use that and go over the entire airplane. David had a scary experience in his Lance. He was approaching an airport and lost power. He ran through a checklist and nothing helped. At about 400 or 500 feet, descending toward a beach, he got a stall warning. The stall warning caused him to pitch forward abruptly, and the engine restarted. He was able to come in and land normally. After some extensive testing they found that a spring had broken in a mag. David thinks that maybe the spring was wedged in the wall of the case, and dislodged when he pitched forward. The hosts don't see how that's possible, but without further information, can't make a better diagnosis. Ray has a P210 and used an in-flight mag check to diagnose a problem. He was flying back to the States from Canada and he noticed the engine was running a bit rough. He checked the mags and found one wasn?t operating properly. He later decided to stay on one magneto. He?s gone through three magnetos in the past few years. He wonders if continuing the flight on one mag was a good idea, and what he should do now. They all agree that he did exactly the right thing by continuing and flying on one mag. Mike said he hates pressurized magnetos, and he would swap them out for electronic mags ASAP. 

Why you shouldn't jam the throttle forward launches this episode. Also, Mike, Paul, and Colleen help an owner with high oil temperature, advise a builder on engine modifications, help ease the mind of an owner with water in his tanks, and discuss how best to use a borescope. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Juan has a turbocharged 210 and he's having trouble going full power on takeoff. He flies out of a high elevation in Colorado, and when he rapidly goes full throttle the engine will quit. It's a bad idea to jam the throttle forward quickly, Mike said. That's especially true with turbocharged engines. Mike said he throttles slowly enough that he's about at full power at rotation speed. Paul points out that even if your oil is at 130 degrees on the gauge, that's not the temperature in the entire system. Everywhere outside in the hoses, etc, is colder. Advancing the throttle quickly can choke the system. Also, in the turbo 210, you can't just slam things forward. You must modulate the manifold pressure because overboosting can flood the engine.  Andrew has a 310 with high cylinder head temps and oil temps on his right side. Some new plugs and new baffling has helped his CHTs come into control. His oil temp is still high. He's replaced the vernitherm, sent out the oil cooler for overhaul, and done some other troubleshooting. The hosts suspect airflow because it happens under reduced power on descent. There's a baffle that separates the cylinder and oil cooler that Mike thinks could be an issue. Paul suggests flying with a GoPro or a borescope camera in the cowling to see what happens in flight.  Dan is building an RV10 with an IO-540 that he's going to overhaul before he installs it in the airplane. He's considering going to 10:1 pistons and porting and polishing and he's wondering about performance and reliability. Mike throws a little cold water on Dan's plans. He thinks it's not worth the risk. Colleen made a pro/con list and she said they are forged, which makes them stronger. They are more energy efficient, but that means they burn more fuel. There's a different magneto timing. They run at a higher pressure, and that probably means they'll need to replaced sooner.  Dennis gets water in the left tank of his Piper M600. His mechanic checked the cap, didn't find an issue, and swapped caps. Now both tanks have water. Paul said it could be that there's no new water, but leftover water from long ago. The water that collects sticks to the sides of the tanks and then rolls around as little balls until it finally makes it to the drain port. In other words, he suspects it's all old water that is just working its way out.  John has a borescope and he's wondering how to best put it to use. Mike mentioned Savvy's new borescope image collection efforts, and he refers to the intro, where they discuss the standard set of images. 

Mike, Paul, and Colleen help an owner with a bad lifter that shows itself after oil changes, guide an owner through a change his maintenance schedule, discuss what constitutes damage history, and take a guess at why POH numbers change over model years. Send your questions to [email protected] for a chance to be on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Steve has a 1975 Taylorcraft with an O-200. After oil changes one of his cylinders has some valve clatter. It tends to go away sometime later, only to come back after the next change. The oil filters are always clean and the oil analysis is good. Paul said there?s not much he can do about it, and Colleen said it?s also not a big safety of flight issue. Mike suggests they measure the dry tappet clearance to see if it?s wide enough to accommodate a larger pushrod to help eliminate the problem. Colleen said she read about a technique to fly it full power for an hour to see if resolves. They call it an Italian tune-up. Jim is on board with condition-based maintenance, and wants to alter the rubber hose component change schedule in his Rotax. Mike suggests that Jim can extend the change interval to maybe 10 years because he lives in the Midwest, and keeps his airplane hangered. The hosts discuss their method for inspecting hoses, how to manufacture them, and the various materials and considerations. Ken is considering a Cessna 180 with damage history. It was repaired and has flown 200 hours since repair. The damage history in question wasn?t so much damage as an improperly installed part that was replaced. Metal was found in the filter, a top overhaul was completed, and the owner is confident the airplane is running well now. Mike said the two things he needs to consider are whether the cylinders were reworked appropriately, and whether they were installed correctly. Considering it was a reputable overhaul company, the hosts are confident everything is ok to move forward. Scott wonders why on the same airframe, the performance speeds change over time. Paul guesses that early performance numbers were a combination of optimism, marketing, and guessing. And newer numbers are spot-on and well tested. Mike guesses that aircraft generally get heavier over time and maximum gross weights increase, necessitating speed increases.

Prop hubs that were nearly scrapped, how to properly measure the oil level, semi-synthetic oils, and tachs that don't agree are on tap for this episode. Email [email protected] for a chance to get on the show. Join the world's largest aviation community today at www.aopa.org/join Full notes below: Bill has a Cessna 182 with a prop that hadn?t been overhauled for about 7 years and 600 hours. This past March he had to send the engine off for some work, and he decided to send the prop off at the same time. They told him the hub was close to being trashed because of corrosion. He?s worried if he had gone another year the prop would have been scrapped, and he?s wondering what he can do to maintain the hub. Paul said he regularly sends out props that are 12 years old and he?s never had a hub rejected, but Colleen said her hub was rejected for corrosion. Mike thinks prop shops are zero tolerance outfits. He said just because they find something wrong with it doesn?t mean it was unsafe. Prop failures just don?t seem to be a problem, the hosts agree. The bottom line: don't send out your prop unless you absolutely have to. Tate is wondering how to accurately measure his engine?s oil level. He suspects that we add oil more often than is necessary because many of us check the level after flying, and seeing it lower, think that we?ve burned oil during the flight. Paul recommends picking a consistent interval to determine oil consumption, ideally at least 24 hours after shutting down. He said if you check the oil level right after shutting down and it says 6, you probably have 7 or 7.5 quarts. Mike said the only way to check consumption accurately is to check how many quarts you add over the course of an oil change interval because that?s averaged over many more hours. Rex is trying to avoid sludge in his engine and knows synthetic oils cause problems, but he?s curious about semi-synthetic oils. Mike said it?s more of a concern in Continentals than Lycomings. He recommends if Rex wants to do that he stick to unleaded fuel. He is considering running 50 percent mineral oil to compensate for the problem of keeping the solids in suspension. The original tachometer and the tach in Pete?s JPI run at different speeds. After many years of operation there?s now a big difference in time between the JPI and the mechanical tach. He wants to know which time to use for maintenance and aircraft valuation. Always use whatever time runs the slowest, Mike says. 

This episode is all about engines--how to fix one that runs rough, how to save money when buying one, why one went bad so quickly, and how to preserve one during a build. Email [email protected] for a chance to get on the show. Full notes below: Brendan?s friend has a Taylorcraft with a tricky engine issue. It started with low rpms in flight, and has since been repeated on the ground. The mags have been rebuilt, both mags swapped, cylinders reworked, new carb swapped, new plugs, and they even bypassed the fuel system. Colleen suggests new plugs to ensure they haven?t been accidentally dropped or damaged. Paul suggests basic things such as the carb valve improperly moving. James and a few partners are looking at their first airplane. He?s interested in the costs and complexity of things such as retract versus fixed, constant speed versus fixed pitch, turbo versus normally aspirated, and more. Colleen said she recommends four-cylinder aircraft because of the cost and complexity. They all agree that constant-speed is a big improvement for not much more money. With retracts, insurance is a concern. Colleen said she paid a lot for maintenance the first two years on the gear, but it?s been otherwise trouble-free. Mike said turbocharging does add some expense. He said to budget to change the turbocharger once between engine overhauls, and maybe some additional exhaust system maintenance. Will found metal in his filter during an oil change and found a pitted lifter when borescoping, and is worried about a spalled cam. There?s only 200 hours on the engine and he flies regularly and uses Camgard. It did sit for six months during maintenance, but he had a dehydrator on it at the time. The hosts go through a complete troubleshooting and logic process to discover what might be wrong, and they plead with Will to get to his mechanic quickly before the case is split. Tim is building an RV-14 and just ordered his engine. He?s wondering how to keep it corrosion-free while he finishes the airplane. Their first advice is to follow the manufacturer?s guidance carefully to keep the warranty intact. It comes bagged with a desiccant pack that indicates if moisture levels get too high. But that system is only set up for a few months. Mike said you can only partially pickle it by swapping the desiccant packs, and maybe a dehumidifier. There are models that use desiccant packs, or an electronic one called a Black Max. 

How far can you go with preventative maintenance? The hosts discuss this, plus oil-soaked plugs, a strange fuel smell, morning sickness, and more. Email [email protected] for a chance to get on the show. Full notes below: Lamberto has a 152 with oil soaked plugs, and is having to clean them every 25 hours. He wants to fix the problem, not simply deal with it. His mechanic suggests a harsh chemical. He?s tried new plugs without success, the hosts agree his BY plugs are the best for oil-fouling anyway. A solvent won?t help, Mike says. He suggests a ring wash, which involves filling the cylinder with a mild solvent, then pulling the prop through the combustion cycle. That forces the fluid through and cleans little by little. If you try to pull the prop through it?s probably too late and the cylinder needs to be removed and the rings probably replaced. Colleen likens it to flossing. Darin is curious about how far he can push preventative maintenance. His thinking is that if you can clean and gap spark plugs then you should be able to do the same to fuel injectors, and so on. Mike says it?s not entirely clear. The FAA has issued a letter of interpretation basically saying that the list in Part 43 is a list of examples, not an exclusive list. Cristopher flies a 172XP in a club in Germany and wants to fly beyond TBO, and also solve an oil issue. He thinks it?s coming out of the induction system drain. The only way that can happen is via the intake valve. They recommend borescoping the cylinder to confirm the leak. Callum has a Bonanza and smells fuel in the cockpit when transitioning to lean of peak. Paul suggests checking the throttle body area behind the panel. The mechanical changes when you lean can cause it. Mike knows of another airplane where this has happened, and they isolated it to a leak in the fuel selector. When you lean a bunch of fuel goes back through the return lines, he said, and any leak could show at this point. Jason has a 182 with an O-470 with a cylinder that is acting up on start when it?s cold. His engine monitor shows very low EGT when starting, and takes as much as a minute to 90 seconds to come to temperature. The CHTs are also much lower. The hosts agree that he definitely has the symptoms of morning sickness, and it?s time to ream it. 

How cold is too cold the fly? Mike, Paul, and Colleen answer this question, and help an owner solve radio problems, advise an owner to fix his probes, and describe the process to become an A&P in the latest episode. Send your questions and comments to [email protected] for a chance to be on the show. Full notes below: Chad has a Cirrus and he?s looking for some cold-weather guidance. A mechanic told him that subzero temps aren?t recommended for a piston. The POH says that flights below -23 degrees Celsius need the cowl inlet plates. The hosts agree that there?s no problem flying in cold weather, but cold starting requires some care and preheating. Mike said the only problem with low oil temperature is that it doesn?t boil off the moisture, and low cylinder head temperatures could bring lead scavenging problems. Colleen said that lead deposits only matter on valves because it could prevent them from seating properly. But, that can be cleaned off if it occurs. Andy has an LX7, a turbocharged airplane. His TIT sensors don?t seem to be working. He?s been using CHT and EGT as a proxy for TIT and he wants to know if that?s a problem. Why not just fix it, Mike says. Andy said he is planning to fix it at the next annual, but Mike said to deal with it now. They recommend a range of troubleshooting options, but agree that it's not a probe issue. Darrell has a radio in his Ercoupe, but above 1,200 rpm it is static-y and unreadable. He?s checked the antenna, the coax, the mags, and more. Paul said it?s most likely a connection issue. He recommends starting with the Veclro microphone key switch. Next move to the microphone plug, which often oxidizes. The hosts also recommend checking the P-lead. Chase wants to get his A&P based on some of his own owner maintenance, refurb work, and building an airplane. He wants to know how to log his time. Mike said this is highly variable based on the inspector?s preferences, so he recommends calling the FSDO to ask what they want. When Mike went through this process he went back and recreated some of his previous experience on an Excel spreadsheet. Paul helps his employees get their A&P by recording the N-number, date, description, and time in a logbook. It?s important to note that there?s no calendar time limit of how far back you can go.

A compass that works on the ground but not in the air leads to a fun debate between Mike, Paul, and Colleen. Plus, the basics of lean of peak (again), jailbreaking a Rotax, and the liabilities of being a mechanic. Send your questions to [email protected] for a chance to be on the show. Full notes below: Blake flies a Mooney that has a compass with a mind of its own. On the ground it works well, but in the air it vibrates a bit, but otherwise doesn?t move. Paul said his fuselage can become magnetized, which would obviously impact the compass. To solve this he says you need to degauss the frame. Mike suggests he start pulling circuit breakers to see if that fixes it. Colleen thinks it?s a current issue since it gets better when the RPMs decrease. With higher RPMs the wires in the airplane essentially become small electromagnets. Lenny is concerned about the liability of working as a mechanic in retirement. Paul said there is liability, but that the job is worth it. Mike says you either worry about or you insure against it. He describes his idea of a maintenance club. The concept is that a group of aircraft owners comes together and hires a mechanic who only works on their airplanes. The mechanic makes more money and the owners have better access to service. Andres flies a Bonanza lean of peak, and he wants to make sure he?s avoiding the red box. Mike said there?s a theoretical red box that only exists at GAMI on a test stand. Everyone else must use cylinder head temperature. With CHTs of 380 degree F, Mike said Andres is completely fine. The red box has fuzzy boundaries. He thinks of it as shades of alarm as you get closer to the center of the box. Colleen said her technique is to get on the lean side and just operate where it sounds and feels the smoothest. James has a Rotax 912iS engine on an experimental. It requires about 40 psi in the fuel system to operate. He thinks by updating the fuel computing he could lower the fuel burn, which is currently 4 to 4.2 gallons per hour. Rotax offers a higher level of controller that the hosts recommend he buy. They also recommend he leave the fuel system alone and work on another upgrade instead.

While one owner has too much of a good thing and lots of shops to choose from, another is second-guessing if the massive check to the cylinder shop was necessary. In this, our first crack at twice-monthly episodes, Mike, Paul, and Colleen spend more time as therapists and counselors than technicians. Submit your questions to [email protected] for a chance to be on the show. Full notes below: Chris has a 182 with a recently overhauled engine that he?s concerned is making too much metal. In fact, the lab called after his most recent oil analysis to draw his attention to the report. The experts see the trends coming down a bit and think he really doesn?t have anything to worry about. With a clean filter inspection, they recommend keeping an eye on it and continuing to fly. Mike has a Malibu and he recently replaced all the cylinders and he?s wondering if he wasted his money. His oil analysis had high nickel, and he was experiencing oil pooling and low compression. He wants to know if he could have lapped his valves to save the cylinders. Unfortunately for Mike they agree that the valves would have been great candidates for lapping. Kevin has access to four maintenance shops on his airport. He has used two of them thus far and he?s wondering how to manage relationships and expectations when working with multiple shops. Mike said he?s a big believer in getting different sets of eyes on an airplane because each IA has his or her own style and focus. The disadvantage is that many shops will start from zero with a new customer, and doing the AD research and other items will take time and money. In Paul?s shop the IAs rotate airplanes, giving customers the benefit of multiple eyes under the management of one shop. He doesn?t recommend swapping shops every year, instead maybe waiting a few years. Steve has gone down the rabbit hole on the wobble test and he has come to the conclusion that the tool doesn?t really clear up the process. Paul said although he has a custom tool, he never uses it, preferring to just ream the guide and not taking the time to measure. 

Did Paul give us the definitive guide on how to hot start an airplane? Try his technique and see what you think. Also, unnecessary cylinder removals, a faulty tach, and a letter writer and guest who question if burping is safe. Send your questions to [email protected] for a chance to be on the show. Full notes below: Walt has a Seneca and has had to replace three cylinders in the last five years. He?s concerned that his mechanic caused the problem after hammering on his exhaust to remove it. The hosts don?t think the incidents are related. While it?s not usually a good idea to hammer on the exhaust, they think it could be useful and safe in limited circumstances. Mike hones in on the reason for the cylinder replacement, and encourages Walt to be more suspect of the need to replace the cylinders in the future. Tim thinks his tach is off. He has an alternative device that also reads rpm that shows a different value, so he?s wondering what he can do to adjust or fix his tach. Paul said the tach is technically adjustable, but being an instrument, it?s not something an owner or even most mechanics can do. Unfortunately the hosts agree it?s time to replace it. Luke operates a few Extra aerobatic airplanes, and he constantly struggles with hot starts. He has been resorting to blowing large fans up through the cowling, but that?s not always practical. In a Continental it?s recommended to run the fuel pump for about two minutes to purge the hot, boiled off fuel and flush the system with cold fuel. Paul said his technique works on Lycomings and Continentals. Start with everything forward with the pump on. Then listen, and as soon as the flow stabilizes and sounds like it?s pumping liquid, you?re done. Mixture and throttle back, but keep the pump on. Crack the throttle, engage the starter, and then advance the mixture control over a few seconds. Thomas has a Mooney and he tried the burping procedure from a recent episode. But the next flight his attitude indicator didn?t come online, and he heard that turning the prop backward can ruin the vacuum pump. The hosts have all heard this concern as well, but Mike?s never heard a confirmed case that turning the prop backward causing a failure. Regardless, this seems to be an issue with older styles of pumps. 

Live from EAA Airventure 2023, check out our second in-person show. The questions come fast, and everything from proper leaning to oil leaks is covered. Can Oshkosh-goers stump Mike, Paul, and Colleen? Full notes below: The first question has Colleen in stitches. Can you widen the gap on your spark plugs to get more horsepower from an engine? Short answer? No! Don?t do it, the hosts agree. Even Colleen, who races airplanes at Reno, says she?s never heard of doing this. Richard has a 182 and says the book will allow for high rpm and low manifold pressure, or low rpm and high manifold pressure for a given percent power setting. He wants to know which is better for the engine. The hosts say that rpm puts strain on the engine, so they would choose high manifold pressure and low rpm. The idea of ?oversquare? is a relic and not at all true, they say. Julie has a 1979 Grumman Tiger and she wants the hosts to address owner-produced parts. Owner-produced parts must be made to the original spec from the manufacturer, which can be hard to track down. But, assuming the owner can find the spec, he or she must be involved in the manufacturing process. Ultimately it?s up to the mechanic to decide whether or not to install the part, and therefore take on all the liability. Bottom line is work with the mechanic early to get his or her blessing. Vedant asks how many more hours he can operate the 2,900-hour engine in his Bonanza. His engine has good compressions and only burns a quart every 20 hours. Colleen said conditioning monitoring is all about catching early indications of problems. Mike said there are only two compelling reasons to overhaul an engine. One is that you have solid evidence that there is something wrong in the bottom end that can?t be rectified without splitting the case. The other reason is that you can?t sleep at night. Terry has a 182 with an O-470 and can?t keep cylinder 1 below 400 degrees, even at altitude. That?s the right rear cylinder with a vertical baffle right behind it. He checked that. When it?s one cylinder Colleen said it?s usually airflow. Paul suggested a GAMI lean test and an induction leak test as well, just to be sure. Rex has a 182 and wonders about flying in the smoke that?s been prevalent around the country this year. The consensus is that smoke won?t hurt the engine, but changing the oil and induction air filter more often are good ideas. Tim wants to know about leaning his Mooney M20C. He wonders whether he should lean until it?s pretty smooth or really smooth. Mike said you have to accept a small amount of additional roughness if you want to run really lean. David has a 1979 172N and he?s wondering if he can use Camguard with his Lycoming 0-320-H2AD. Mike said he should use the AD-compliant additive just to remain legal. Greg asks for downsides to using variable-timed electronic ignitions in a carbureted engines. Paul said the risk is if they advance too far you can get into detonation. He recommends checking the cylinder head temperatures to make sure they aren?t too high. Advanced timing will show high CHTs and low EGTs, and retarded timing is the opposite. Jack has a Piper J-3 Cub with a Continental C-85 with only 40 hours. After flying he finds oil all over the belly but no obvious leaks. Paul said if the breather line is cut at the wrong angle it can actually cause a vacuum and draw oil out of the case. Mike said to borescope the cylinders with the intake valve open. It should be dry. If it?s wet you know where the oil is coming from. Mike asks about rpm on the ground and lead scavenging. The hosts say to lean as far as you can, regardless of rpm. Mike said not leaning on the ground is the biggest cause of valve sticking. Paul mentioned that Cessna now recommends leaning while at 1800 during the run-up and he said you can use that setting for ground leaning.

How to start an airplane, whether or not to wash an airplane for an annual, flying through smoke, and high TITs are all on tap for this grab bag of an episode, as Mike, Paul, and Colleen take your toughest questions. Write to [email protected] for a chance to be on the show. Tony owns a turbo Twin Comanche with 300 hours on the engines. He burns about 14 gallons per hour on takeoff, but he thinks he should be burning 16 gallons per hour. As a result, he gets high cylinder head temperatures quickly, and needs to reduce power. He also sees power surging on the ground when his engines are hot, but not cold. Paul thinks the fuel servos and engine-driven fuel pumps are both in question. Colleen recommends pulling one servo and sending it out, just to see if it makes a difference. Paul suggests maybe a different shop to see if he gets different results. He?s had many experiences where there?s a problem with a component that overhauling doesn?t fix, despite the overhaul facility saying there?s no issue. Andy questions whether shops follow the regulation that requires an aircraft to be cleaned during an annual inspection. Apparently his shop said they will wipe off big globs of dirt, but don?t do a full cleaning. Paul said they definitely wash the airplane, but often it?s after the inspection is complete so they can see the various oil and grease patterns. The wash is complete, but basic. Really dirty airplanes are written up as a discrepancy so the owner can take care of it later. Matt has a 210 and he?s worried about exceeding the turbine inlet temperature. They try to fly it below redline, but they exceed it easily and quickly on takeoff. They are hoping to more aggressively lean and take advantage of low CHTs. Mike said not to worry about going over the TIT redline for short periods. Redline on the turbocharger is meant to protect the turbine wheel because the blades can creep from centripetal force when they get too hot. But flying lean of peak is possible because TIT is often exceeded only briefly during the transition, and not when settled. He also suggested that unusual TIT numbers can be a result of improper mag timing. Nathan is a flight instructor and wants to clear up the madness around starting carbureted small engines. He sees people use the primer, pump the throttle, and do all sort of other unusual things. He wants to know the right way to do it. Mike said that using the throttle, or using the accelerator pump, puts the fuel in the wrong place. He also thinks that if it?s possible, prime while you crank the engine for best efficiency. Paul said if the primer isn?t helping to start the engine, it?s quite possible the primer isn?t working. He finds a lot of the old primers are clogged, which leads to other techniques. Erik has a question about how smoke impacts piston engines. With wildfires being more and more prevalent, whether or not to fly during wildfire season is a growing concern. Colleen said she sees increased dirt in her oil analysis, her air filter gets dirty, and the leading edges of her airplane get dirtier. But the hosts agree that it's generally not a concern, especially for brief periods.

In two separate but similar incidents, owners want to know whether their cracked spark plug insulators caused pre-ignition or if detonation ruined their plugs. Mike, Paul, and Colleen tackle those questions, and many more. Email [email protected] for a chance to get on the show. Full notes below: Mitch has a Mooney that developed a strong engine vibration a few minutes into a flight. He quickly discovered the problem as the cylinder head temperature was climbing, and he went full rich and reduced power. A subsequent borescope inspection discovered no anomalies, so he?s wondering what happened. Many people online said it was a clogged fuel injector, but Mitch suspects pre-ignition. So do Mike, Paul, and Colleen. They hone in on a cracked spark plug nose insulator. Mitch is also concerned about which came first. Did the broken insulator cause the problem, or did detonation break the plug? Thanks to good photos and data, the hosts are convinced there wasn?t a serious detonation event, and it was isolated to a plug problem. Brian wants Mike, Paul, and Colleen to comment on the validity of an unusual procedure. He has a friend that ?burps? the engine after every flight, and he swears it keeps his oil much cleaner. It works like this: after every flight the friend will open the oil filler cap and turn the prop backward. Every time he does it a bunch of gasses escape. It?s a legit thing to try, say Paul and Mike. Colleen is shocked because it seems an odd thing to do, but getting a lot of the moisture out?which is the majority of what is coming out?can only be good for the engine. Les has a Lance, and on a recent humanitarian flight with a plane full of passengers his engine started shaking badly. With no good option to set down, he reduced power and nursed it back to the airport. No borescope necessary here, the evidence was obvious?total piston destruction. Again the hosts suspect a cracked insulator, and again they think it was probably the spark plug?s fault, and not something that originated with detonation. Mike doesn?t seem classic detonation symptoms on the cylinder. Les isn?t convinced since his mechanic didn?t find a cracked insulator, something Mike doesn?t buy. Even extremely small cracks can cause problems, and with such a violent event, it likely would have been cracked in the process. Richard has a new carb temp gauge and he is looking for advice on how to use it. Specifically he?s found that in some phases of flight he has to have carb heat on at least partially to keep the carb temp high enough to stay out of the icing danger zone. But he?s also heard that it?s bad to operate this way. The hosts agree that doing so could be bad, but with the gauge in place he shouldn?t worry. It gives him the information he needs to operate safely. Jay discovered a broken oil control ring after just a few hundred hours on a cylinder, and he?s wondering if his operating procedure caused it. Jay flies a Taylorcraft and it has a new carb that enables leaning, whereas previously it was always flown full rich. Not to worry, say the hosts. Excessive leaning wouldn?t have caused the problem, and he should feel safe to continue leaning. 

Paul and Colleen broadcast from Dayton, Ohio, for Aviation Maintenance Technician Day, and together with Mike, do their best to help owners suffering with engine problems, mysterious cold air leaks, improper fuel indications, and more. Send your questions to [email protected] for a chance to be on the show. Full notes below: Jim has a heavily modified Twin Comanche that blows cold air on the back of his neck, and he can?t find the source. He suspects it?s from the rear tailcone, but he can?t figure out how to stop it. Paul suggests it could be the rear bulkhead or from the wing roots. Despite his attempts, it?s actually gotten worse and is now blowing air on his legs that varies based on attitude, whether the heater is on, and maybe even heading. Mike suggests a camera and tufts of yarn in the tailcone to see where the airflow is coming from. Paul suggests that the airflow from the heater might be blocked, causing problems. They said if you pull out seats and floor panels on a test flight with a mechanic he might be able to find the culprit. Sam asks about dynamically balancing a propeller. When is it necessary? Who does it? The hosts agree it?s a good service to do when you change something, although the prop should be balanced from the shop. Arnold has a Bonanza that improperly shows the fuel level on the right tank, but only after it?s burned a few gallons. This is using Ceis fuel senders on a Garmin display. After many attempted fixes, it?s still reading low. Paul said they have to forget what they think has been eliminated and instead go and try to recreate the problem on the ground. Mike suggests putting a small vacuum on the tank to see if they can do just that. Keith has a turbonormalized Bonanza and wants to make sure he treats it well. He?s been surprised at how contentious the turbo versus non-turbo debate is. Mike said he thinks it?s a geographic problem where people on the East Coast think it?s useless and everyone out West thinks it?s a great tool. Although a turbocharged airplane is easier to abuse, the mechanisms themselves don?t have any inherent downfalls. So long as you treat it well and know that turbochargers are wear items, you should be fine. Ben has a Bonanza and he wants to know if he can remove the rear seats and remain legal by doing the weight and balance math based on station and equipment info from the manual. He also wants to exchange the fasteners to make it faster and easier. Colleen said a new weight and balance from an A&P is required once in order to be legal, and the hosts agree that fasteners approved for a later model Bonanza should be easy to get approved for his airplane. Kyle has a problem on both of his airplanes. His Cessna 182 with a bit more than 1,800 hours had a bent push rod and a bit of his lifter body had cracked as well. He is wondering if he should overhaul now since the case has to be opened anyway. Mike said the answer is always based on what happens after the case is split. If everything measures well then an IRAN is a good way to go, but an overhaul might be warranted too. It all depends on the inspection. The Continental C85 in Kyle's Luscombe has a stumble around 1,800 or 1,900 rpms. He thinks it might be a lean mixture issue because a bit of carb heat helps. Paul suggests he borrow a carb from a friend to see what happens. Even though Kyle has already overhauled his carb, Paul said he?s seen numerous times where even a supposedly overhauled carb won?t perform any better because they can?t duplicate the issue on the bench. A different carb would help to isolate the problem. 

A grab bag of unique questions come at Mike, Paul, and Colleen this month, including whether to buy new or overhaul, how prop stops work, what happens when you reduce from wide open throttle, and avoiding tiedowns. Submit your question to [email protected] for a chance to be on the show. Full notes below: Dale has a Seneca and he?s looking to the future and having to overhaul two engines. He?s wondering how to decide between factory new, reman, or overhaul. Not surprisingly, they suggest flying your current engines as long as possible if they are treating you well. When the time comes that you have to change engines, Mike said his general rule is that if the engine has treated you well to consider a field overhaul. If there?s a concern about the current engine, he said to consider a factory engine. More control over the process is another reason to do a field overhaul. Jim has a question about his L-3 with a Continental A65. He has an updated carburetor with a mixture control. A challenge with that engine is that you don?t get an onset of roughness when leaning. It just tries to quit, and without an electrical system, an in-flight shutdown isn?t ideal. He?s worried that a big stumble is startling and he pushes it too far rich again, putting him in the red box. Mike said there?s no need to go to roughness. You can lean only to the first indication of power reduction. Dubs has noticed that after leveling in cruise, when pulling the throttle back from wide open, it moves a significant amount before the manifold pressure changes. Yet in doing so he?s reducing his fuel flow. He?s wondering why this happens. Mike thinks it?s possible Dubs has a carb with an enrichment circuit, which gives more fuel at wide open throttle, meaning fuel flow will come down as soon as throttle is reduced. The hosts discuss how Dubs? operating practice is how Cessna 182 pilots with 0-470 engines should operate to improve mixture distribution. The impact butterfly valves make is very non-linear, they say. The first 5 to 10 degrees of tilt won?t make a big difference, for example. Phillip is a maintenance tech in a shop that adjusted the low pitch stop of a prop based on the recommendations of the prop shop. He?s wondering why it was successful. Paul describes how a prop adjustment works, and why some airplanes don?t make full rpm until they?re down the runway a bit. Richard?s Rotax ran rough on a run-up, and after some troubleshooting he still hasn?t found the culprit. All winter it ran fine, but he?s concerned it will happen again in warm weather. Since this happened on both magnetos it?s likely not a spark plug. Colleen is wondering if the rpm range had an impact because the Bing carbs have three distinct operating ranges. If it happens again Colleen recommends isolating it and first checking the spark plugs, then maybe cleaning the carbs, and finally looking at the fuel delivery lines. Mike thinks it has to be a fuel system problem since it changes with temperature. Brennan has a nice Mooney M20J that he wants to continue to take good care of. He now lives in a very humid environment and can?t find a hangar. He left the airplane in his old hangar and can barely get to the airplane to fly it. He?s wondering what would be the least damaging practice?fly less or keep it outside. The hosts think it?s better to get the airplane closer and fly it while doing his best to keep corrosion away with freshwater washes, corrosion treatments, and maybe covers.

With two important airworthiness directives recently issued for Continental engines and Cessna Cardinals and 210s, Mike, Paul, and Colleen dig deep on the surrounding capacity and safety issues. Then they take calls on the limitations of engine monitors, and how normal can look anything but. Submit your questions to [email protected] for a chance to get on the show. Full notes below: Michael has a turbonormalized Bonanza and he?s concerned his system isn?t operating properly. When full throttle on takeoff it overboosts, so he goes to partial throttle, which lowers the fuel flow. The controller and waste gate were both checked with no change. Mike says it?s a very bad idea to limit the manifold pressure with throttle. Continental says overboosting by 3 inches is a non-event. What is a big event is limiting fuel flow. The fuel flow is determined by the upper deck pressure, which could be adjusted. Either way, Mike says that Michael can leave it alone and give it all the beans. Paul is shopping for an engine monitor and is wondering if the hosts have any advice. Of course they do! Mike recommends user-programmable alerts. Otherwise they recommend you buy the one that best fits in your panel. A slew of recommendations on how to use it follow. Laurie?s engine runs roughly in a certain rpm range unless she leans to peak EGT. The hosts soon learn that she operates from an airport at more than 7,000 feet. Mike thinks it?s likely this is normal behavior because the engine runs too rich at full power at such a high elevation. John thinks he might be experiencing morning sickness on his RV-7?s O-360 engine. He is noticing an increase of lead buildup each time he borescopes it. The CHTs are also too low, at around 300 degrees in the winter. He felt the engine was running rough for a few minutes after starting, as well. The hosts look at John?s photos and think his engine is perfect. Paul mentions that so long as the valve seats well, the gunk in the cylinder is fine. They offer a number of ideas on increasing his CHTs. Steve is frustrated with his engine monitor because he's experiencing what he believes are nuisance alarms. The issue is that his engine manual and POH have different numbers, and the engine monitor is programmed with the POH numbers. The engine monitor can be reprogrammed, but it?s expensive and requires input from a mechanic. This is mostly an issue with engine monitors that are certificated for primary replacement.

Mike, Paul, and Colleen debate the difference between a bribe and incentive pricing, discuss how much carbon in the oil filter is too much, counsel an owner how to keep his alternator belt on, and reveal what's in their go-bags. Email [email protected] for a chance to get on the show. Full notes below: Jim is finding a significant amount of carbon in his oil filter after oil changes on his Cessna 182. He wants to know if the carbon is a problem. Mike said the carbon itself isn?t a problem, but it?s indicative of something else that is worth tracking down. He said the oil is getting overheated, carbonizing it. It?s most likely from excessive blowby. They recommend compression checks and borescoping to see if he can find the culprit cylinder.     John flies a Mooney with an electronic ignition system, and he thinks the airplane is slower since the system was installed. Mike thinks it?s possible it wasn?t timed properly. They see it often because the electronic ignition system is timed differently than a traditional magneto. If the EGTs are up and CHTs are down, that's further confirmation.     Jim is frustrated with the alternator drive belt on his 182. It comes off the pulleys about once every 10 hours. Paul said it?s very common. Counterbalances on the crankshaft are a potential problem, but a last resort. Grooves in the pulley could also be the culprit, as could excessive play on the shaft on the drive pulley. Paul also suggests trying a solid belt instead of Jim's current segmented version.     David is trying to make a kit of tools and spare parts to take while on cross-countries, and he is looking for recommendations. Paul said he has two criteria. First is something you?re willing to change. The second is to take any special tools or parts that most shops don?t carry. Mike said he takes common-failure items for the specific airplane. On his 310 he carries a vacuum pump, for example. Colleen said she always carries duct tape and tie raps, a screwdriver in order to take the cowl off, and a first-aid kit.     Dustin has a controversial question about a recent interaction with a shop. During the buying process of an engine overhaul, an owner found out a supplier offered the shop $2,000 to the shop if the owner went with them. The owner found out thanks to the shop's honest disclosures, but questioned if this is an ethical practice. Mike thinks this is no different than a wholesale/retail markup. Paul said he understands why this feels different, but he thinks it?s legit. Mike recommends asking your shop what they are making on your part, and if you?re not happy with the amount to negotiate it.  

This month Mike, Paul, and Colleen give an owner the ammo he needs to not overhaul his engine prematurely, help console an owner with super hot cylinders--maybe, console another with super cold cylinders, and give cover to a pilot who wants to refill his own oxygen. Send your comments and questions to [email protected] for a chance to get on the show. Full show notes below: Pat?s Diamond has one suspect cylinder. The mechanic said it has failed inspection, and needs to be replaced, but the engine is beyond TBO and they are refusing to fix it without an overhaul. The question hits right at the heart of some of Mike?s frustrations with shops and their lack of evidence-based practices. He suggests lapping the exhaust valve to bring the compression back up, and then keep flying it. Kirk wants to refill his own oxygen system, but it?s not covered specifically in preventative maintenance regulations. The hosts asks if you?re allowed to add oil, fuel, and air to the various systems. Of course you can. It?s servicing the airplane. Mike says there is no talk of servicing in the regulations, but of course we all do it legally. They view adding oxygen in the realm of servicing. Robbie doesn?t believe his CHT gauge in his Socata TB-10. The factory single probe gauge shows 500 degrees and rarely goes below 400. He?s wondering what he can do to make himself feel more comfortable that it?s a gauge problem. Colleen asks if he smells anything. She smelled burning oil when hers went beyond 420. The hosts agree that given his great borescope photos, and good oil analysis that he?s probably ok. They also suggest checking the engine grounding strap that goes from the crankcase to the firewall. It grounds the engine to the airframe, and without it the probe wire could be finding some interference. The paint would also change color at 500 degrees. Will is seeing exceptionally cold cylinder head temperatures on his Comanche. On a recent flight to New York, he saw temperatures in the high 140s during descent. He knows his probes are good, so he?s wondering if there?s a lower limit and if it's hurting the engine. After discussing a number of possible causes, they discovered that Will is going full rich on descent, which is absolutely contributing to the low temps. Mike said that while you may have to enrichen a bit in the descent, if you forget the engine will remind you by running a bit rough. That?s followed by a detailed discussion of leaning for the climb and descent. Carl flies a Cherokee 180 and is wondering if flying it on cold winter days with density altitudes below sea level could hurt the engine. The hosts agree that the takeoff mixture setting is so rich that there?s enough of a margin not to worry. Detonation could be a concern in certain experimental engines, but a normal certificated engine has a big detonation margin. 

Did you know things live in jet fuel? These are the fun things you learn being a mechanic. Mike, Paul, and Colleen enlighten us on this strange fact, and tackle questions on leaning, burned exhausts, puddles of oil, and how not to set your airplane on fire when preheating. Email [email protected] with your question for a chance to be on the show. Full notes below: Chris owns a Piper Comanche with 1900 hours on the engine, and it that has developed an oil leak of one quart every 2.5 to 3.5 hours. Fuel tank sealant and an air/oil separator didn?t work. Paul says there?s no way he is leaking that much oil from a leak in the crank case. He suspects another issue. Mike said Lycoming has a procedure to slather a sealant on the case seam. Since there?s a lot on the belly Mike thinks it might be going out the breather. He suggests a ring wash. Lance flies a Cessna 185 and is worried about his leaning procedure. He?s recently replaced all six cylinders and is concerned his leaning procedure may have caused some problems. He?s worried that by learning until roughness and then enriching slightly he?s in the ?red box.? Paul said if the engine is running rough, at least one cylinder has quit firing, so he's very lean at that point. Mike said the GAMI spread should be less than a gallon per hour. The GAMI spread is the difference in fuel flow between when the first cylinder peaks and when the last cylinder peaks. Assuming he only enrichens enough to stop the roughness, and no further, and his GAMI spread is good, he?s likely fine. If the CHTs are all below 400 degrees F and he?s less than 60 to 65 percent power, he has nothing to worry about. Chris number two asks about corrosion in fuel tanks. He works on turbine aircraft and often sees a brown staining on fasteners inside fuel tanks and he?s wondering whether it should be replaced. Paul said it?s only when the materials starts to degrade when you need to worry about it. He said a good rule of thumb is that if the part number imprint is still there that it can be left alone. Brad is wondering about pulling the prop through prior to starting. The general idea is apparently to move the oil around. Colleen said there?s no truth to any of it. You?ll scrape the oil off the cylinder walls if there?s any left. You can either preheat to heat the oil up on cold days, or you can pre-oil the engine if it?s been sitting a long time. Paul warns against pulling the prop through for safety. There?s no value in turning it backwards, and turning it forward can start the engine if you aren?t careful. Barry has a Tiger that had a muffler that lasted a long time when he ran rich of peak. Since running lean of peak or near peak his flame cones have burned out within 400 hours. Colleen talked to a local exhaust rebuilder who said he believes running lean of peak is burning up exhausts. It?s not because of the exhaust gas temperature, per se, but more likely the oxygen content of the flame at those mixtures. Jeff had a student with a Cessna 172 that he thinks has a tachometer from a Piper. It was replaced in 1993, and had been correctly signed off every year since. He?s wondering how that happens and what the pilot?s responsibility is in this case. Mike, Paul, and Colleen agree that an IA wouldn?t necessarily catch it on the inspection, although instruments and markings are part of the annual inspection checklist. Paul said he?s mostly concerned with the redline, and not necessarily the green arc.

Adam flies a Piper Warrior owned by his friend. On a recent flight he experienced some morning sickness that he was able to resolve. On a subsequent flight the owner had morning sickness as well. The owner is considering a top overhaul. Mike said he has two options, and a top overhaul isn?t one of them. The first is to do a wobble test and the second is to skip the test and go straight to reaming the valve guides. Paul recommends doing only one at a time. He said not to fly it again until the procedure is completed. They?re worried that flying it after the morning sickness could have caused damaged, so a borescope inspection is in order as well. AOPA r Kevin flies a Cessna 172XP that he suspects is the slowest one of its kind. It flies about 15 knots slower than book speed, and he?s seeking a remedy. Paul suggests first checking the rigging, specifically to make sure the flaps are completely retracting. If the flap rollers touch the end of the slots before the switch turns off, it will hurt the motor. But if there?s a gap after the motor has stopped, they aren?t full up. Totally ignore the fairing that?s riveted to the cabin, he said. He would also check the lifters to ensure complete motion. Mike suggests that is the airplane climbs at book values, he has a drag problem, but if it climbs worse than book, it?s a power problem. Greg is hoping to overcome the supply chain issues by purchasing a ?lifetime? oil filter. Being able to open the filter is the best thing you can do to know how the engine is wearing, Paul thinks. Mike thinks the filter inspection, while possible with a reusable filter, would be a messy, complicated job. Ken said he heard an adage that you should check your EGTs at 1,000 feet, and then lean in the climb to match those numbers, and he?s wondering about its validity. The hosts all completely agree, and it?s generally how they fly as well. Patrick flies a Cessna 170 and he?s wondering why his cylinders have a different CHT limit. Mike thinks the difference is probably due to the fact that CHTs are measured in a different position in his engine than others and the O-300 has a different cylinder design. After a cylinder swap he?s also wondering why break-in procedures sometimes call for changing power settings. Mike said he?s never seen a justification for this practice. He has broken in his engines by running them as hard as he could, keeping in mind cylinder temperature limits. Miko maintains his own airplanes and is looking for approved data. He?s struggling to find reasonably priced maintenance manuals. Clearly the manufacturer is the first place to go. Paul uses ATP for his airworthiness directive research. Typically they sell subscriptions, which are quite expensive though. He said you might be able to get a shop to give you their old paper manual because most have transitioned to digital. Colleen also uses McCurtain, which they don?t think exists any longer. Essco is still around and sells digital versions of scanned manuals.

Engines are the focus this month as Mike, Paul, and Colleen talk about valve failures, valve springs, burned valves, and more. And of course we had to have a leaning question. Send your questions to [email protected] for a chance to be on the show. Full notes below: Marius owns a Cessna 172XP that routinely has a rough mag check on run-up. His mechanic is recommending fine-wire spark plugs after finding oil on the plugs. He has since bought them, which set him back more than $1,500. Colleen recently purchased some as well, and thinks they definitely work better. Nigel wants to get deeper into condition monitoring on his turbonormalized Bonanza, specifically with the turbo system. Mike said that the turbo controllers almost never fail. Waste gates are fairly problematic. Eventually they?ll start to stick, which you can tell by an inability to properly hold manifold pressure. The turbocharger itself is inspected at each annual. The shaft is checked as part of the inspection, and there should be a little wiggle in the radial direction, but none in the axial direction. Also look for blade scrape and cracks in the flange. Paul also recommends checking turbo system oil inlet and outlet check valves. Michael had a rough-running engine when he reduced power. They pulled the exhaust valve and found the keeper groove of the valve was much smaller than it should have been, and he?s trying to figure out what caused the problem. He?s now finding that the third cylinder is also behaving the same way. Mike thinks it almost looks like it?s been ground down. He suspects an installation problem. The hosts recommend pulling the valve covers and springs to check the rest of the cylinders. Viatcheslav is wondering about rotator spring failures and how they cause exhaust valve hot spots. He owns two airplanes, one with a Continental O-300 and one with a Continental E-225, neither of which have rotator springs. He's curious how and if his valves rotate without it. The hosts break the news that he does, in fact, own two of the few engines without them. He can continue to watch for hot spots on borescope inspections, and also occasionally lap the valves as a preventative measure. Reid is concerned about a burned valve on his 172. He leans aggressively, but doesn?t have an engine monitor, and wondered if his leaning led to the burned valve. His only source of information is the stock EGT gauge. Mike did some research on the Alcor gauge. Most of the Alcor gauges aren?t calibrated, and many don?t have temperature references. Some have an adjustable pointer that the pilot can set. Others have a calibration screw. On those, the manual tells you to lean to peak EGT at an altitude where you can get 65 percent power at wide open throttle, and then set the needle to match. Mike thinks the changes Reid is seeing could just be changes in the mechanism of the gauge. It?s not meant to measure absolute EGT. Furthermore, leaning doesn't burn valves. That's most often caused by a bad set.

Making new parts, protecting parts, replacing parts, and identifying bad parts is the theme of this month's episode. Plus, a spirited discussion on fuel selectors. Send your questions to [email protected] for a chance to be on the show. Full details below: Greg is building an RV-10, and he?s wondering if he should prime all the skins while he builds to ensure there?s good protection inside and out. Mike, Paul, and Colleen disagree on what to do. Paul thinks he should skip the priming and instead spray Boeshield or AV-8 because you can spray it on after the airplane is built. It?s a one-time application. Mike thinks if Cessnas have lasted for decades without being primed, Greg should be ok as well. And Colleen is on the fence. Bottom line: there?s no right answer, just the right answer for each builder. Russ is trying to help a friend. His 182R lower door hinge is cracked and the mechanic isn?t any help. Russ owns a machine shop and thinks he can manufacture the part. Mike says that it is important not to create a part that is better than the original. He must create an equal part. Something better would require additional approvals. Paul says it?s important to get the mechanic involved early because he will assume the greatest liability, and must be comfortable installing the owner-produced part. And many mechanics aren?t comfortable installing something without a part number. All agree that the hardest part of making the part will be figuring out exactly what the original material is and how it was made. Frank wants to use a synthetic oil in his 182 because he?s had such good results in his car. Mike makes the point that there?s no full synthetic oil on the market. He suggests 15w50, a semi-synthetic, but only because Frank is able to regularly run mogas. Those who only run with 100LL shouldn?t use a semi-synthetic, Mike said. Ryan is part of a flying club and they have a Cherokee 140 with an intermittent landing light. He was able to get the light to work regularly by applying a bit of heat to the circuit breaker, which makes him think the breaker is bad. The hosts recommended buying his own breaker and asking the mechanic to replace it. It?s a relatively easy fix. They recommend going to a pull breaker instead. Ernest said his mechanic hears a knock, but the hosts all agree that the video clearly sounds like lifter clatter. Mike say to look left, look right, make sure no one is around and pour in some Marvel Mystery Oil, which can reduce lifter clatter. When the lifter doesn?t fully lift there is play in the valve train, which makes the noise. Cleaning the lifter is an option, but it is a lot of work. Paul thinks it?s possible it only happens at lower oil pressures. With normal oil temperatures he should have 80 psi oil pressure at cruise, and not something lower, like 65. Alex sparked a spirited discussion on pilot technique. He?s wondering about how to test fuel flow on the ground. Some airplanes call for changing tanks on the ground, others don?t. Colleen thinks it?s ill-advised to switch tanks during the run-up. Paul said the fuel bowl on many carbureted engines contain about 30 seconds of fuel at cruise power. He said you?ll never run the engine long enough on the second tank to properly test it. This led to a long discussion about Cessna?s fuel selector design. Mike said he never moved the fuel selector off of Both in his 182, and furthermore he doesn?t understand why Cessna even made it. While the Cardinal will drain from the selected tank, the 182 doesn?t work the same way. If you burn off the right tank, for example, the fuel will be replaced with fuel from the left tank, and not air. Paul said he would stay on Both if he could. They then debate whether to use the fuel pump when switching tanks, and for many reasons Paul recommends sticking to the POH.

Because it's impossible to make it through an episode without discussing leaning, Mike, Paul, and Colleen hit it from two sides this month. A debate about inoperative equipment, and why mechanics reach for the pressurization cart first. Submit your questions to [email protected] for a chance to get on the show. Full notes below: Jay flies a Lycoming IO-540 on an experimental with one cylinder that peaks long before the others. He?s tried everything, including switching injectors. Mike suggests checking the valve lift to make sure the action is as good as the other cylinders. Paul suggests an in-flight manifold leak test to show things that can?t be duplicated on the ground. It works like this: Climb to 5,000 or 6,000 feet where the full power setting is the same as ambient pressure, stay at full rich on the mixture and let the EGTs stabilize. Then lower the manifold pressure by 7 or 8 inches and watch what happens to the EGTs. If one goes up while the others go down, or vice versa, it shows a leak in the induction system. Gary is a CFI who wonders about strain on a constant-speed propeller during power-off landing practice. With the engine at idle the hosts think it?s fine to pull the propeller back during gliding. Since his first question was so quick, Mike, Paul, and Colleen decided to give him another, and here Gary wonders if leaning to peak EGT is acceptable to the engine. We know leaning to 50 degrees rich is detrimental to engines, and we know lean of peak is safe if done properly, but little is said about running at peak. Given his comfortable CHTs, Mike said running at peak EGT is totally fine. And Paul said he ran at peak EGT for years in his Piper Twin Comanche with no issues. Eric wonders what triggers an overhaul and asks what happens once you go past TBO. Close condition monitoring is essential, says Mike. The two biggest tools are an oil filter inspection for the bottom end, and borescope for the top end. Oil analysis is also helpful, but Mike said the filter inspection is more important. Paul suggests making sure owners speak to their mechanic first to ensure they?ll sign off the airplane if the engine is past TBO. Although there doesn?t appear to be any legal basis to do so, some mechanics refuse to sign off an annual if the engine is past TBO. Scott wondered about inoperative equipment and how to decide if it?s ok to fly. Mike points to FAR 91.213D. Because it?s in Part 91 it applies to everyone, regardless of aircraft. It includes a logic flow that details how to deal with inoperative equipment. In order to fly with inop equipment it must not have been required for aircraft certification, in Part 91.205, on the aircraft?s mandatory equipment list, or be a hazard to fly without it. Toby has a Cessna 414 and has struggled with pressurization over the years, and he asks if his troubleshooting flow works well. He?s a little frustrated because most mechanics first hook up the pressurization cart, even though in his experience the test usually doesn?t show much. Mike said the cart is used to test the outflow side of the pressurization system because it bypasses the inflow system. Twin Cessnas have a very convoluted inflow side, where tons of things can go wrong. One reason to go straight to the cart is because troubleshooting the inflow side requires digging, Paul said. Troubleshooting mindset also matters. A slow-evolving problem is different than a sudden issue, for example.

This month Mike, Paul, and Colleen take questions from owners with round engines, fabric, fire-breathing aerobats, and more. Send your questions to [email protected] for a chance to get on the show. Full notes below.... Bruce has an a Continental O-300 and recently replaced all six cylinders. Number four is still running hot, and number six used to run hot. He played with the baffling to reduce the temps on number six, but number four is still around 400 degrees in cruise. He also added a splitter on the top to direct more air. He has checked the induction. By changing the baffling to help cool number six, Mike thinks he has made the problem worse for number four. The plate at the front is there to prevent number six from hogging all the cooling air, he says. When this happens Mike naturally looks at the inter-cylinder baffles, which are easy to mis-position. The first troubleshooting step is to shine a light from below and check if you can see it from above. If so, air can escape and cooling efficiency drops. Derek is looking to buy a Maule that?s been sitting in a hangar and he?s wondering how to check the condition of the Ceconite fabric. The Ceconite manual has inspection procedures. Colleen said it?s not the fabric you?re necessarily testing, but the dope. If the dope can block UV light then the fabric is presumably fine. If you push against the fabric and it?s pliable and flexible, that?s good. You can find the manual online https://www.conaircraft.com/_files/ugd/d66f5e_9653c858211f4636b7d4fcbb4787e540.pdf Oscar is wondering if safety wire isn?t meant to hold a torque, why don?t we use the same size for everything? Mike said there are three common sizes of safety wire, but almost everything is .032. Paul mentions that turnbuckles are an important exception. AC43.1B Change 1 https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.13-1B_w-chg1.pdf describes how to safety wire turnbuckles. An interesting and detailed discussion of turnbuckles that has nothing to do with safety wire follows? Scott has an N3 with a Wright engine and he?s wondering about leaning. The manual for the engine says not to lean, and he asks whether it would be better to leave it full rich or lean a bit. Mike calls for a vote and says that while in cruise he would lean it to the onset of roughness, and enrichen it only enough to smooth out the engine again. Colleen said she loves leaning and would lean as well. Surprisingly, it?s unanimous and Paul said he would lean as well. Bob has an Extra with a Lycoming IO-580 engine. He has noticed that his old Extra, with the same engine and virtually the same airframe, ran much cooler. He said he can barely lean at all now because of temperature limitations. Number five is the hottest, but only by a little. Paul wonders about his leaning technique, which is to lean slowly to find peak. The guidance is to pull much more quickly. The hosts also focus on a cabin heat shroud that?s in the cowling but not hooked up to the cabin. Bob thinks it partially blocks the exit airflow, which is a critical part of the cowling cooling system. 

Introducing our first live show from EAA Airventure 2022! Join along as Mike, Paul, and Colleen handle questions on the spot from the audience at the AOPA Program Pavilion.

Is shock cooling myth or reality? Can you run lean of peak with a carbureted engine? These questions and many more come at Mike, Paul, and Colleen in this month's episode. Send your questions to [email protected] Full notes below: Jerry has an RV-4 with a new battery but the original alternator. When he starts the engine and then turns on the alternator, he sees a big amperage spike. He tested turning on his alternator before starting, and sees the same spike. That piece of information is critical because according to the hosts it means it must be an instrument indication. Without the engine operating and the alternator not turning, it can?t possibly be producing current. Ken has a Mooney M20 and thinks the inside of the tail section is messy and ugly. He?s looking for a way to clean it out. A vacuum won?t work because the flakes are sticky. Paul suggests that because it?s sticky someone has sprayed a corrosion inhibitor and only hand scrubbing will get it completely clean. Once it?s clean, he suggests spraying in a thin coating of Cor-Ban (https://zipchem.com) or Ardrox AV8. Dave flies a 1946 Cessna 140 and a Hatz biplane with a carbureted engine. He wants to know how to fly lean of peak. Mike says that Lycoming engines are pretty symmetrical out of the factory, which means they are often ok to run lean of peak from the factory. Continentals are less so. The rear cylinders tend to run leaner and front cylinders tend to run richer. By reducing the droplet size you can better dial it in. Do this by using a little bit of carb heat to better atomize the fuel. The other method is to back the throttle off a little bit to make the airflow through the carb more turbulent. Without instruments to help, the technique is to lean aggressively until the engine stumbles and then enrichen only until the engine runs smoothly again. Steve is wondering about unleaded fuels in development. He wants to know if the hosts would hesitate to use any of these new fuels in their airplanes. And also if their operating procedures will change as a result. Mike, Paul, and Colleen say they would have no hesitation running one of the fuels once it?s approved. They also don?t expect any operating changes. Guest Mike wonders why the hosts don?t ever talk about leaning in a descent. Host Mike stresses that although power changes should happen somewhat slowly, it's not as slow as he used to think. Lycoming recommends limiting cooling to no more than 60 degrees per minute, and Mike has an alarm set on his engine monitor for 30 degrees per minute. The only time it ever goes off if he?s doing an ?extreme slam dunk.? Colleen makes the point that aerobatic pilots often oscillate between full idle power. Hannah flies a Super Decathlon and wants to make sure she takes care of it while doing aerobatics. Colleen says to keep it under 6Gs and a close eye on the engine mounts because they are the flexible attach point between the engine and the airframe. Although Hannah was originally asking about general tips, the hosts find out that she has experienced a governor failure that spewed out almost all her oil. Mike asks about rpm overspeed and Hannah said she noticed that used to happen before the governor failed. She?s also seen a drop in oil pressure in the dive. If her inverted system isn?t working well it would starve the governor of oil.

Oil all over the nose, cylinders that are too clean, and bush propeller repairs. Mike, Paul, and Colleen handle it all this month. Submit your questions to [email protected] for a chance to be on the show. Adam wonders what to do after a prop overhaul left him with a huge puddle of oil and some shaken nerves. His plan is to remove the newly overhauled prop and send it to the manufacturer. Paul questions whether it was an install error because a seal between the shaft and the prop seal can be broken during the install process. Mike agrees and thinks the manufacturer won?t find anything wrong. Mike has a Cessna 150 with a 150 horsepower upgrade. He said the seller recommended not running it on Autogas because Lycoming never approved it. Mike says check Lycoming service bulletin 1070AB. It lists which fuels are approved for which engines. Paul correctly makes the point that the whole point of the STC is that it enables you to do things that the manufacturer wouldn?t necessarily have allowed. Mike said so long as there isn?t an operating limitation for specific fuels, you don?t even need the STC. Buying the STC gives you a flight manual supplement and placards. Lyle has concerns about his oil analysis and how it relates to the way he operates his Cessna 182. After an engine reman his chrome levels were going up, but are now coming down. His mechanic was concerned he was flying too lean because everything on the borescope looked too good. The hosts describe the ideal leaning procedure as this: Don?t look at any gauges. Lean it until it starts running a little rough, and enrichen it only until it smooths out, and no more. He also has high silicon levels, which Mike attributes to a carb heat door that isn?t sealing fully. Lyle further wonders about his exhaust gas temperatures, which Paul and Colleen remind him are irrelevant. EGTs are only useful for looking at trends, according to Colleen. Mike said it?s not a measure of stress on the engine?only a measure of how much energy is being thrown out the exhaust. Dewayne has an exhaust leak in his Tripacer. The two pieces of exhaust come together with a clamp, and a test shows it to be blowing more than bubbling. Paul said you can generally ignore leaks that only bubble, by blowing leaks need to be fixed. He recommends an expander and working very slowly to try and get the two pieces to better match. You can only push it about a thousandth of a inch, Paul said. Rowan asks how to know when a knick or dent in a propeller becomes unsafe to fly. We all check our props before we depart, but few of us have a guide to know whether prop damage is normal or unsafe. Paul said a good rule of thumb is that if you run your fingernail along it and it catches you need to address it. But if it just runs along roughly, but doesn?t catch, it?s ok to continue. But, that?s not an owner-approved repair. Mike said the problem is that they create a stress point. A sharp point at its apex is more worrisome than a rounded dent. Advisory Circular 43-13 Chapter 8 Section 4 gives details for mechanics on how to deal with knicks, and it?s actually a pretty generous standard.   Chris can?t fly as much he?d like, and he wants to know if he should risk a ground run if the airplane has been sitting but he doesn?t have time to fly. Water being a byproduct of combustion, a short flight can be more detrimental to a flight than letting it sit. If the moisture doesn?t boil off it only adds more moisture to the engine. Mike said where Chris lives on the Gulf Coast, he would buy a dehydrator. There?s no hard and fast rule on how long is too long to go between flights, but the hosts say once every few weeks is fine, and try to keep it to less than a month. 

From the seemingly benign--what tire ply to use--to the extreme--hitting 500 degrees on a cylinder--Mike, Paul, and Colleen face it all this month. And we mean all, like Ron's 172 that produces a loud bang exactly two minutes after shutting down. Submit your questions to [email protected] Full notes below: Larry has a turbonormalized Beechcraft Bonanza. When it came time to replace his tires he decided to go to with 8 ply, but he later researched and found the type certificate specified 6 ply. The Goodyear spec sheet seemed to indicate he would be over the weight limit on 6 ply. Paul said the older lighter Cessna 210s were 6 ply, but were upped to 8 ply later on. He suggests it?s ok to go up in ply if the dimensions are the same. Colleen also admitted she went from 4 to 6 ply on her Cardinal at the last tire change. Mike says if Larry is in violation by using a higher play, then he is as well. He mentioned a recent tire supply problem that prompted him to go up in ply. Randy bought an engine without logbooks that was intended for a Cirrus SR20 in Guatemala City. He?s wondering if he can put it in a Cessna 175 or Skymaster. Colleen brings up the lack of AD compliance data. Some ADs are for internal engine parts that can only be verified with paperwork or by opening up the engine. Ultimately Paul said it?s up to the mechanic who has to hang the engine and whether he or she is comfortable with its AD compliance status. Mike said from a safety standpoint he would want to pull the lifters and look at the camshaft. And he would pre-lubricate everything, including the cam while the lifters are out. If it?s not making metal within 100 hours, you?ve dodged a bullet. Tom is wondering how to tell if his engine with a constant speed propeller is producing full power. At sea level he has 29 inches of manifold pressure with an ambient pressure of around 30 inches. All the hosts agree that this sounds about right, given that you?ll lose some pressure through the intake and other areas. Jeff has a Cessna Cardinal with a recently installed electronic engine monitor. He saw on climb-out near El Paso that the cylinder head temperature on the third cylinder topped out around 500 degrees. Now he?s wondering what to do. Compressions are excellent and the oil analysis is good. He also fixed the baffles, which fixed the problem. Mike suggests borescoping the piston. Failure points would be corner melting or the pockmarked appearance of detonation. If the piston looks ok, you?re probably fine, he says. Ron has a 172 that has an unusual problem. Every time the fuel level is below half, and two minutes after engine shut-down, there?s a loud bang. It sounds like someone hit the top of the wing with a bat, he said. Paul thinks it?s possible the tank is being overpressurized, and the reason it takes two minutes is because the weep hole is so small that it takes that long for the tank to equalize. He suggests quickly depressurizing after landing by taking off a fuel cap and seeing if air rushes by. If the tank vent tube is in the wrong position it can cause the overpressurization. Robert has a Cherokee 140 that is burning about a quart of oil per hour. Mike said oil consumption is always a cylinder problem, but not always a problem with all cylinders. Borescoping the cylinders may help identify oil pooled in one particular cylinder. Oil consumption comes from three sources--crankcase compression, which will show as oil out the breather tube. Burning oil will show as soot on the airplane. Or there could be a leak. Paul suggests a ring wash to further identify the problem cylinder, and potentially solve the issue. A detailed explanation is available at bit.ly/solventflush

This month Mike, Paul, and Colleen tackle questions about inexpensively improving aircraft paint, cylinders that are too cool, low compression readings, and a magic floatplane that burns less fuel with its floats fitted. Plus, the ultimate stumper, an airplane that can't turn left. Submit your questions to [email protected] Full notes below: Eric has a Pitts with an unusual problem. When he turns left the engine starts to sputter, and when he turns right the rpm increases. They initially suspected the flop tube in the header tank. Although it looked to be in good shape they replaced it anyway. They also overhauled the wobble pump, and carefully inspected all the fuel lines. There were no obvious problems. Colleen reached out to Pitts experts. They suggested making sure the fuel divider was properly bled. Eric is pretty sure it?s not vapor lock. ?It has to be the flop tube,? Mike and Colleen say. Another theory Eric and his mechanics came up with is the fuel controller. They sent it for service, and the shop found that the throttle body mounting hole had a little rounding from vibration damage. They thought that maybe turning opened it to allow in more air, leaning the mixture. Once he gets it back, Eric is planning to do a test flight. Doug is looking at his paint job, and while he knows that paint is an important protector, he?s trying to avoid a costly and invasive full repaint. Paul said you can absolutely go in and touch it up yourself. You can use a touch-up brush, sprayer, or anything you like. Colleen said that the vast majority of the work is in prep, and that the paint color will never match because the original paint will have faded. ?Be careful and measured,? she said. Mike said to make sure the aluminum is clean and corrosion-free prior to applying the paint. Paul suggests Scotch Brite and Alumiprep (https://www.aircraftspruce.com/catalog/cspages/alumiprep.php) and Alodine (https://www.aircraftspruce.com/catalog/cspages/alodine1201.php) to make the primer stick. Get an automotive paint person to help blend the colors, he said. And Mike says to make sure you don?t sand through the thin layer of Alclad. Andy wonders if his IO-540 is running too cool. His cylinder head temperatures only top out at 310 degrees, which he's reading on an Electronics International engine monitor. Mike said EI makes two probes for their engine monitors, and the P-100 always reads low because there?s an air gap at the cylinder head probe that makes it artificially low. The only downside of running too cool is potential lead scavenging. Mike said to pull the spark plug and use a borescope to look at the exhaust valve stem. If there isn?t deposit build-up, then there?s nothing to worry about. But lots of lead means you have to somehow increase the temperature. Tom is worried about his compression readings. His O-320-D2G had a cylinder of 38/80 only 18 hours after overhaul. Two more cylinders are reading a little low now at 100 hours. He thinks all of them are leaking a bit, and have gotten slightly worse. He expects them to get to the low 60s, and he?s worried that when he wants to sell, buyers will baulk at the numbers. So he?s wondering if he should just replace the cylinders now so he never has to worry about it. The hosts all agree he is overanalyzing and should monitor as normal, keep flying, and work on the cylinders only when it?s required. Jeff has a Cessna 180 floatplane and a new fuel flow meter has him thinking. He?s wondering if the performance charts are based on tach time or clock time. Paul assumes that because the tach was the only instrument they had when they certified the airplane, it has to be tach based. ?They had clocks when that airplane was built,? Colleen says. She and Mike are sure it?s clock time. Jeff also wonders why his float supplement shows fuel flow lower than the original handbook. With a difference of only .2 gallons per hour, Mike says they are effectively the same number, and not to worry about it.

You may think an annual inspection includes a verification of the accuracy of your fuel gauges, but you'd be wrong. Nor does the IA check the accuracy of your tach or any other number of instruments. This information comes to a pilot undergoing a first annual. Mike, Paul, and Colleen also tackle oil loss and temperature issues, why we stop our engines with the mixture, and the difference between a major and minor alteration. Submit your questions to [email protected] for a chance to be on the show. Full notes below: Chuck flies a 1941 Interstate Cadet with a Continental 85-8F engine. He had a prop strike four years ago, was inspected and got some new rings, gaskets, and a few other parts. He?s noticed he goes through a quart every four or five hours, compared to 15 hours prior to the overhaul. Mike suggests there may have been a problem when honing the cylinders, and Colleen suggests borescoping to see what the honing looks like now. Paul said a normal honing crosshatch is about 30 degrees, but that on a teardown they use a ball hone that doesn?t make a regular pattern. If it?s at all shiny it means they?re glazed. But ultimately they all agree it doesn?t matter and that it?s an acceptable amount of oil loss. Tom is a new mechanic who is looking for advice. A friend asked him to install a new stall warning horn to augment the stall warning light in his Cherokee. Paul suggests looking at a newer version of the airplane with a horn and a light, and submitting that information as approved data to the FAA. FAR 1.1 defines a major versus minor alteration. Advisory Circular 43-2B is acceptable methods for aircraft alterations, which Collen calls the bible of alterations. Mike makes the point that it?s a mechanic?s decision as to whether an alteration is major or minor. A major requires someone else?s signature, such as a field approval or FAA sign-off, while minor is only the mechanic?s signature. Jay flies a Mooney with M20F with an IO-360 with a JPI engine monitor. The oil temp probe is located near the first cylinder. On climb it hits 230F and trips the over-temp alarm. In cruise it stabilizes at 195F. The analog probe shows 30 degrees cooler. The hosts aren?t at all surprised that the probes are different. Colleen mentioned that when she changed engine monitors they moved the probe and her oil temps have gone down. Mike said our goal is to usually measure the oil temp at the coolest location. Peter has a Cardinal and is going through his first annual. He is wondering where the accountability is for previous mechanic oversights. His IA has found things like airworthiness directives that haven?t been complied with, a bucking bar left in the airplane, and so on. Mike makes the point that there is a difference between airworthiness discrepancies and things that are more discretional in nature. And all three hosts caution that each annual and pre-buy inspection are unique, and that it?s impossible to snag every discrepancy. Walter asks why we don?t just turn off the key when stopping a traditional piston airplane engine. The hosts agree that it is solely a safety consideration, and meant to get gas out of the system. That way an ungrounded mag can?t refire the engine and create a safety issue with the propeller. Rolf has a TB-20 with an IO-540 engine that?s never been overhauled and is trouble-free. Last year he noticed on the engine monitor traces that the number 1 and number 2 EGTs were very low at low fuel flow. His shop measured the dry tappet clearance and found the intake valves were well in excess of the limit. They were able to bring them within limits, but the EGTs are still bottoming out. Mike makes the point that the valve clearance limit is only to ensure that the amount of play in the system so that the hydraulic lifter can ?take it up.? The hosts agree his engine is in fine shape, and not a safety issue. They do recommend he prepare for an overhaul in the future based on the symptoms.

This month Mike, Paul, and Colleen talk fluids. Danny has an oil leak, Steve has a fuel leak, and Jeff is puzzled by guidance on which oil to use. Plus, a question from a maintenance newbie, looking ahead to overhaul, seeing double on batteries, and a pesky propeller governor problem. Submit your question to [email protected] for a chance to be on the show. Full notes below: Dash has a T-34 and is wondering about the implications of having two 12-volt batteries in series, rather than one 24-volt battery. Paul says one battery is simpler and less costly to maintain, but two 12-volt batteries in series can generally push out more current. You can treat them as one 24-volt batteries and use the applicable trickle charger, Mike says. To do this you would take a 24-volt charger and treat them like one battery, Colleen says. Take the cables and hook up the positive from one battery and the negative from the other battery. They all cautioned to make sure not to hook anything to the short, stout cable connecting the two batteries. Dash also says a mechanic at his airport told him not to continuously charge the battery because it will reduce capacity, but the hosts say that?s bad advice and that a trickle charger can be on the batteries all the time. Danny has a continuously oily windshield on his Bonanza, which he thinks might be coming from the top of the case. The engine has 2,200 hours and looks great on the borescope, and he?s hoping an overhaul won't be necessary. Paul said he definitely wouldn?t pull an engine for this. He goes straight to the crankshaft seal as the offender. Mike thinks the o-ring that seals the prop to the flange is another good culprit to check. Mike said oil coming from the top of the case would go on the back baffles and other spots inside the baffles, not on the windshield. Chris has an O-540 on a Cherokee 6, and although the engine is still running strong, he?s planning ahead and wondering if a rebuilt or overhauled engine is better. Mike said this is the worst time he?s ever seen to do anything to an engine. Colleen said she thinks people are risk averse and she?s always overhauled engines and has been very happy. Mike said the only reason to go rebuilt is if you know you have to replace a major component or if you want to minimize downtime. Mahesh is looking for resources to become better acquainted with managing the maintenance on his Cirrus. The hosts recommend the Cirrus Owners and Pilots Association seminars, owner-assisted annuals, and Mike?s books https://www.amazon.com/dp/B08KHDPPWG?binding=kindle_edition&qid=1643661371&sr=8-4&ref=dbs_dp_rwt_sb_pc_tukn Sebastien and Tim have a Murphy Super Rebel with a governor problem. The propeller wanders 35 rpm up and down, and they?re wondering if it?s a problem and how to fix it. Colleen suggests checking the integrity of the rod end to the bell crank. Jeff has a Lancair and wants to switch oils, but Continental Service Information Letter 19-04 that says operators shouldn?t change oil until the engine is overhauled. The hosts all agree that this was a misguided document, and that switching oils will have no determinantal impact to the operation of the engine. Steve?s Piper Lance is weeping fuel and he is wondering how critical the problem is. His A&P said he could take the tanks out to have them resealed, but all agree that this isn?t necessary. Paul said the Piper maintenance manual and FAA maintenance advisory circular have a good chart to show the various fuel leaks and what to do about them. If it?s not leaking bad enough to pull the tanks he said it?s probably not worth doing anything. 

Mysterious metal in the filter, reporting an owner to the FAA, when to change ELT batteries, and the elusive perfect hot start. This month Mike, Paul, and Colleen handle some of the toughest questions in aircraft ownership. Submit yours to [email protected] for a chance to be on the show. Full episode notes: Brian asks how one is to know when the ELT battery runs for more than an hour or has reached 50 percent of its life. FAR 91.207 requires replacement on these conditions. Short answer: you don?t. The hosts point out that the batteries can?t be load tested and there?s no outside monitor to know how long they may have been active. So, if in doubt, replace them. Ryland wants to know if he can install a non-certified engine monitor in his certified airplane. Mike breaks down the decision tree that leads to an answer with an extreme example?installing a refrigerator in your airplane. You must show it meets the same certification requirements the aircraft had to meet. As Mike said, you have to jump through the same hoops that the manufacturer would have had to do had it decided to install one at the factory. First you must decide if it?s a major or minor alteration. A major requires approved data, which means getting an FAA field approval. If it?s a minor alteration the technician must make the determination that it meets all the applicable certification standards. Most difficult of which is that it doesn?t interfere with other systems in the airplane. Most mechanics won?t take it upon themselves to do that, he says. Colleen said she has gone through the field approval process and it?s quite difficult. Richard wonders if he?s damaging his engine by keeping the rpm below 800 on initial startup. He flies a Cessna Skylane with a Continental O-470. The hosts agree that Richard is overthinking this a bit and there?s no risk of damage at operating at such a low rpm. Mike said he would use roughness as the lower limit. Justin asks about his responsibility to report an unsafe aircraft to the FAA. After an alarming pre-buy inspection of an airplane he decided not to buy, he?s concerned another potential buyer may be at risk. Mike, Paul, and Colleen have strong feelings about this issue. Paul said a pre-buy isn?t an annual inspection, and it?s the owner?s responsibility to ensure airworthiness. This is the only person you should report the findings to, he said. As a follow-up Justin mentions an airplane he was asked to ferry that had a hole in the bottom of the wing. Mike explained the four entities responsible for airworthiness--the factory when the airplane is built, the owner, a mechanic one day a year at the annual, and most critically, the pilot in command. Tim asks aviation?s most difficult simple question?how do you consistently hot start a big bore fuel-injected engine? As a CFI his normal advice to clients is to use the technique that works best for you in your airplane. In his Cirrus Paul goes throttle and mixture forward, fuel pump on until the fuel pressure stabilizes, then everything back, throttle cracked, and mixture slowly increased while cranking the starter. He uses this for hot or cold starts. Mike suggests priming and cranking simultaneously. Paul mentions a technique of running the boost pump on high for at least 45 seconds while the mixture and throttle are at idle cut off, and then performing a normal start. This circulates cold fuel in from the tank. Jared is the maintenance officer of a flying club with a Cessna 172M. They?ve been finding metal in the oil filter that doesn?t look like that from normal sources. Lycoming couldn?t find it, and neither could the shop that did the overhaul 600 hours prior. The overhaul shop did warranty work, including replacing the crankshaft. It didn?t work. Jared had sent in photos and Mike didn?t think they looked like crankshaft issues. Paul thinks the oil pump is a strong suspect. But overall the hosts are stumped, and Jared promised to come back later with an update.

Ever wonder what you're looking for when you preflight a Cessna with those small oil doors? So did our caller this month. Mike, Paul, and Colleen also field questions about a burned valve, winterizing for cold-weather ops, how to do an in-flight magneto check, and whether you'd really run out of fuel before oil with a leak in the gauge line. Submit your questions to [email protected]

This month Mike, Paul, and Colleen dive into questions about valve failures, tracking engine times, aging engine accessories, and worrying cylinder head temperatures. Plus, a question that could only come from an instructor.

This month Mike, Paul, and Colleen tackle everything from radio gremlins to the big questions of aviation, such as an overall maintenance philosophy and the reliability of our aircraft. Send your questions to [email protected] for a chance to get on the show. And please take our survey to tell us how we're doing. You can find it at https://aopa.az1.qualtrics.com/jfe/form/SV_cZSqTKSpaOTVjdI?Referral=APS

This month Mike, Paul, and Colleen tackle questions big and small. A pilot wonders why aircraft engines are so expensive, a young student knows there must be a better way to clean an airplane, and owners tackle concerns over increasing compressions, throttle lag, and avionics. Send your questions to [email protected] And please tell all of us at AOPA how we're doing on podcasts. Take a short survey: https://aopa.az1.qualtrics.com/jfe/form/SV_cZSqTKSpaOTVjdI?Referral=APs

Broken rocker arms, metal shards in the valve cover, and oil in the cylinder, oh my. This month Mike, Paul, and Colleen focus on listener engine problems, give some guidance on mods for an experimental builder, and bust an oversquare myth. Submit your questions to [email protected]

A savvy owner wonders how to trust her airplane with no logbooks, a Cessna pilot is curious if he's getting all the power he paid for, and Mike, Paul, and Colleen tackle an unruly governor. Send your questions to [email protected]

This episode Mike, Paul, and Colleen debate shock cooling, help an owner set his stall warning tab, debunk unapproved equipment myths, give an owner advice on breaking in new cylinders, and more. Submit your questions to [email protected]

This month owners look to settle arguments with their mechanics over tire wear and avionics glitches, one pilot tries to determine myth from reality on keeping fuel tanks topped off, a pilot learns his oil pressure problem isn't a problem, and Mike, Paul, and Colleen describe why detonation is a self-correcting event. Submit your questions to [email protected]

This month Mike, Paul, and Colleen cover the basics of oil analysis, corrosion proofing, fuel selector play, how to pick an overhaul shop, and prop people. Send questions to [email protected].

This month Mike, Paul, and Colleen tackle a number of questions about oil. Where it should be, where it shouldn't be, and why it isn't where you last added it. Plus, a jet pilot is grounded by tires. 

This month Mike, Paul, and Colleen delve into must versus should. Must you open all those inspection ports, is the prop and governor overhaul mandatory, and should one owner retorque his cylinder after a re-installation mistake? Send your questions to [email protected]

This month Mike, Colleen, and Paul revisit sticky valves, diagnose shimmy dampers, give a bit of career advice, and talk about what right looks right on throttle response. Plus, silly pilot tricks with animals! Send your questions to [email protected]

Mike, Paul, and Colleen talk about why lean of peak if beneficial. Also, the hosts tackle questions on sticky valves, how to properly break in an engine, oil consumption, and more. 

Snake oil, cranky turbochargers, oil issues, camshaft rust, and more in this month's episode. Plus, a new owner tries to stump Mike, Paul, and Colleen on propeller rpm checks. 

Corroded control cables, the right oil for engine break in, pesky fouled plugs, and just how far can you push back on your annual. Paul, Mike, and Colleen handle all these topics and more in this month's episode. 

Checking an airplane for aerobatics, engine failures due to oil starvation, mysterious airplane vibrations, and why replacing cylinders could be a bad idea. Mike, Paul, and Colleen handle these topics and more in this month's episode.