Live from AirVenture 2026, Session 2

Engines fail when they're new, not old. Plus, leaning with carb heat, questions to ask as a renter, and Cirrus cylinder cracking. 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: Kevin is looking to rent an airplane from a private owner and he's looking for opportunities on Facebook. When he goes to see the airplane and meet the owner, Kevin is wondering what he should ask. Paul suggests staring with the logbooks and looking for the annual inspection sign off with a note that the ADs have been complied with. Colleen says to start with the books and then go through a thorough pre-flight. If the owner balks at repairs that you consider essential, she suggests walking. The hosts debate the importance of how many people fly the airplane, but settle on the fact that what really matters is a standard squawk sheet. Alan is concerned about the new Cirrus service bulletin that describes cylinder cracks on Continental engines. He asked the shop to inspect per the service bulletin and the shop found a crack where the SB describes. Paul said all you can do at this point is to inspect it frequently, ideally every time the cowling is off. The manifold pressure pull and other pilot actions won't impact this. It's a design defect that has nothing to do with pliot actions.Ike flies an O-200 and he thinks it runs better lean with full carb heat on while in cruise. He's wondering if the unfiltered air is bad for the engine. The hosts say so long as he's only doing it in cruise, it's no problem. Colleen does this with one of her airplanes and her oil analysis doesn't show any additional silica in her oil. Mike suggests he try partial carb heat to get the same effect.Lawrence and his son fly the family's new airplane. He wants to instruct, and his son wants to fly for a career. They've flown 400 hours or so, and the engine is around 2,000 hours since TBO. They do a lot of their own maintenance under supervision, and as Lawrence learns more he wants to be sure he is being safe. Specifically he's looking for signs of when to start worrying about TBO. The engine that you have is more reliable than what you're going to have after you overhaul, Paul said. Colleen mentioned new, defective parts on new engines. The team focus on maintenance-induced failures, etc. The most common reason the engine will need to be overhauled, Mike said, is if the cam and lifters are doing bad. This will show in metal in the filter. But these issues aren't safety issues so much as financial problems. It's about a bulletproof an engine as you can get, Mike says. Accidents caused by engine failure almost always occur when the engines are young, not old, according to Mike. Lawrence wants to focus on what really matters. Mike says there are three things--boroscoping, checking for metal in the oil filter and screen, and watching for symptoms of morning sickness. 

What happens when you shut off the mags in flight? Mike, Paul, and Colleen answer this question, plus Cirrus cylinder woes, lapping technique, and more. Email [email protected] for a chance to be on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Jeff is questioning the part of his checklist that calls for turning off the mags just before shutting down. He remembers doing this accidentially in flight training and his instructor becoming somewhat panicked. The hosts explain that turning off the mags before shutting down is safe and determines if the P-lead is intact. Accidentally turning them off in flight is a different story. Unburned fuel in the exhaust will ignite rapidly and probably ruin the exhaust if you were to immediately turn them back on. If this happens, Paul recommends leaning the mixture completely, counting a few seconds, turning the mags back to both and then slowly brining up the mixture again. By doing this you'll hopefully allow the collected fuel to dissipate. Brian asks about Cirrus cylinder problems after a recently failure caused his partner to execute an emergency landing. The hosts explain that Continental has been having issues with cylinders on certain big bore Continentals. There's an AD that requires the cylinder exhaust ports to be filed, and while they've seen many cracks where the AD had supposedly complied with, Mike said the issue is that most mechanics aren't filing away enough material. However, Paul has also seen cases where the AD was properly complied with and the cylinder still cracked, and even new cylinders that aren't covered by the AD are cracking. He recommends doing a careful visual inspection for cracking near the exhaust port anytime the cowling is off. Yuriy wonders how much exhaust valve sidestepping is too much. Mike said he's had big sidestepping in many of his valves with no adverse effects. They recommend continuing to borsescope a few times a year to ensure the valve isn't burning. As Yuriy's compressions continue to come down the hosts recommend being proactive with lapping. Otherwise they recommend to keep flying as much as possible. Randall wonders how much lapping is enough lapping. He's looking for clarity on when the job is done. Paul invokes the TLAR method (That Looks About Right) while Mike additionally says to invoke the TFAR method (That Feels About Right). They say 4 times with new compound is often enough, but that it's about feel and look of the valve. Mike does recommend a compression check before putting everything back together as a gut check, and that most people new to the procedure often don't go far enough.

The right oil temp, inop and new equipment, and oily turbos are on tap for this episode. Email [email protected] for a chance to be on the show. Join the world's largest aviation community at aopa.org/join Full episode notes below: Grace’s engine runs rough above about 2,000 rpm. She currently has a single probe monitor, and is waiting to install a more comprehensive engine monitor. She’s worried about running too cold, given that her oil temp is relatively low, even in the Pennsylvania summer. It’s not too low in her 180-horsepower Sundowner, Paul said. She’s unsure what’s too cool and how to check to see if there’s too much moisture in the oil, which would indicate it’s not running hot enough to burn off the moisture. Mike said that an oil analysis is the best way to tell, and so far hers have been consistently good.   Boris is looking deep into the regs and is wondering about equipment failures. He has a friend with a Piper Seminole and the manifold pressure gauge was inop. The gauge isn’t listed in the type certificate, minimum equipment list, etc. The current Part 23 doesn’t specifically require a manifold pressure gauge with a controllable pitch propeller. However, 91.113(d) says that the equipment must be operational as originally certified, and Part 23 at the time required a manifold pressure gauge for an engine with a controllable pitch propeller.   Mark is wondering how turbos impact oil. Mike had written that the ratio of displacement to oil capacity is an indicator of how long you can go between changes. An IO-550 with a small sump calls for more frequent oil changes, for example. The other thing Mark has heard is that an airplane with a turbo should have more frequent oil changes, and he’s wondering if that’s true. The turbocharger doesn’t make the oil dirty, Mike says. If the oil cooler is working properly it also shouldn’t make the oil run hotter. Paul also said not to worry because it doesn’t seem to make a difference. Mike said he’s seen really poor oil analysis reports with Cirrus that run to around 75 hours.   Jacob is a new A&P and he’s trying to figure out some of the ELT installation regulations. He’s unsure whether the remote audio and controller is a different installation for the purpose of the STC, regs, logbook, etc. The hosts agree that the TSO that form the basis of the ELT certification requires the remote switch.

A caller wants to know what they don't teach you in A&P school. Plus AD compliance, a scary engine failure, and putting the lean in lean of peak. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join KC wonders why ADs appear on some logbook entries as having been complied with with a terminating action, and in future entries the AD reappears. He discovered this was a common occurrence when he was looking through logbooks as he and a partner were purchasing an airplane. Mike said you can't tell from an AD compliance summary whether something has been permanently complied with. That is found in the logbook through some sort of permanent change, like a kit or STC. If some other IA signs off the AD compliance again it could be because the IA simply missed that the AD was permanently complied with. Paul said he always assumes an airplane he sees for the first time has errors in AD records compliance and he verifies everything himself. Paul said this often happens because the part was changed somewhere in the airplane's history to make it no longer permanently complied with. Jeff is looking to fine-tune his lean of peak performance. He flies an RV-10 with an IO-540. He has a small window in lean of peak where he is running a bit rough, but if he runs more rich the CHTs will climb into the 360-degree range. Mike said Jeff is trying to run too cool. A Lycoming typically runs 20 degrees hotter than a Continental, so he said flying at 400 degrees CHT is perfect and nothing to worry about. Keeping it cooler won't necessarily matter.  Mark is going to A&P school on the side for additional enjoyment and greater involvement in his airplane maintenance. He is at a Part 147 school, and he feels like the education is good, but he's wondering what else he needs to know about GA maintenance. Paul explains that school is a great intro to the various topics, but it's not long enough to be detailed in all facets of aviation maintenance. Most specific learning is on the job training. Mike suggests Savvy's new IA renewal program, which anyone can take for free.  Frank has a turbocharged Rockwell Commander. The engine sputtered and stopped at 1,200 feet. He turned back to the runway and made it safely. His first thought was water, but none was found. The mechanic sent his magneto out but didn't find anything. Paul said it wouldn't be an ignition problem because both would have to fail or one would have to go badly mis-timed. A key piece of evidence is that the engine did end up restarting again on his approach to the runway. The hosts think it's fuel delivery. The electric boost pump was on. Mike suggests it was a stuck carb float. Paul said the engine will run on a similar engine for about 23 seconds with fuel just in the bowl. 

Join Mike, Paul, and Colleen for a second live session from EAA AirVenture in Oshkosh 2026 as they are try to answer the audience's most pressing maintenance questions. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join

Join Mike, Paul, and Colleen as they take questions live from the audience at the AOPA tent at EAA AirVenture 2026.

Which oil is best, where is the oil going, running lean of peak with a carb, and how to fly a turbo are on tap for this episode. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full episode notes below: Chris' American Champion Super Decathlon has an oil consumption issue. While his engine was apart after a prop strike the cylinders were honed, and he broke it in properly. He has since replaced cylinders, broke it again, and is still only getting three hours per quart. He said oil is coming out of the fuel servo, which everyone has told him is normal, but the hosts quickly disagree. Mike suggests borescoping the back side of the intake valves and looking to see if one is oily. If it is, chances are the intake valve isn't seating properly and is being sucked back up and burned. Chris is trying to run lean of peak with a carbureted engine. He has an O-360 and he wants to make sure he's not doing anything wrong. His technique is to lean to the point of roughness and enrichen only enough to smooth things out. Mike said that's a solid technique and that most four-cylinder carbureted Lycomings run well lean of peak because they have a good balanced mixture distribution. Mike said not to worry about how lean he is. If the temperatures are within limits and the engine is running smoothly, you are good. James has a Piper Turbo Lance and he wants to make sure he is running it properly. His manual has a five-minute limitation on takeoff power, and he's wondering where that comes from. Paul said the older Cessna 210s have a five-minute limit at 2,700 rpm, and they discovered that the limit was all about noise, and not about the health of the engine. They told James to check section 2 of his POH, limitations, which would require the procedure regardless of the reason. Mason uses Aeroshell 100 plus Cam Guard. He's heard that straight weight oil remains on engine parts longer during periods of mis-use. But he read that Aviation Consumer tested oils and that corrosion protection was more correlated to added chemistry than viscosity. He's wondering if there's data to support either position. Mike said he'll recommend a multigrade for pilots who operate in a variety of temperatures. Mike things the cleanliness probably has more to do with Cam Guard use and operating lean of peak.

A fidgety fuel problem, octane ratings, and water in the oil are on tap for this episode. Email [email protected] for a chance to be on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Gareth has a turbo Arrow and he's been fighting a problem with fluctuation fuel flow. Sometimes the engine quits on the ground or runs rough in the air. They've checked the fuel spider, fixed intake leaks, overhauled the fuel pump, an exhaust leak, and much more. Paul is convinced that air is entering the system or there is a vapor issue. He suggests checking the heat shields near hot parts of the engine, etc. Mike suggests that it could be related to upper deck pressure, which controls the aneroid in the fuel pump. Matt wonders if fuel octane impacts timing. He has a Cessna 150 and is running autogas, and he's wondering if his ignition timing should be changed to accommodate a difference in octane. Paul said the airplane was certified with 80 octane, so it's fine to keep the timing as it is. Scott is wondering about an alternative to safety wire. A company called Bergen makes a safety wire alternative and he's wondering if it's legal to use on FAA certified airplanes. Mike said even if the company doesn't say it's FAA certified that it would almost certainly be a minor alteration, and therefore at the discretion of the installing mechanic. Paul uses them in certain applications and likes them. Scott has a IO-540 on a Socata Trinidad and was about to overhaul his engine, but found Mike's maintenance philosophy. He's now at 2,300 hours and counting. Everything looks good except that water occasionally shows up in his oil analysis, and he's struck out finding help through his mechanic. The water is a byproduct of the combustion process. When you shut down the crankcase is full of steam, and that steam then condenses into water. You can help keep that water down by taking off the oil cap after shutting down, or by hooking up an engine dehumidifier. Scott flies about 100 hours a year evenly spread out, and he lives in a dry environment, so the hosts agree the dehumidifier probably isn't necessary.

Very cold cylinders, sort of warm cylinders, turbochargers, and pressurized mags are on tap for this episode. Email [email protected] for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full episode notes below: Bill has a Cessna 182S with the Lycoming IO-540 and he has a temperature issue with his number 2 cylinder. Climbing out at full rich he would back up the mixture a bit at 1,000 or 2,000 feet and the CHT would climb to about 405. By going full rich again he can keep it below 400 degrees. Mike said the problem is totally in Bill's head. A CHT of 405 is a perfectly respectable temperature for a Lycoming. The redline on the cylinder is 500 degrees, so there's no need to worry about 405. Mike recommends keeping Lycoming cylinders below about 420 degrees. Daniel has a Columbia 400 with a TSIO-550. He's been thinking about how car turbochargers don't have enough exhaust gas pressure to start working until a few thousand RPM and he's wondering if airplane turbos are the same. Paul said the waste gate closes immediately upon startup, so all the exhaust runs through the turbocharger from the beginning. Bob is wondering about corrosion on pressurized magnetos. Mike has previously explained that they are prone to corrosion because of water entering the system. Bob wonders if because the water entering the system can only be in the form of water vapor and because the vapor is coming from clouds, which are low in the contaminate that cause corrosion, if Mike might be overstating the problem. Mike doesn't disagree with Bob's theory, but in practice the issue is real and prevalent. Adam flies lean of peak in his Columbia and his CHTs can be as low as around 240 degrees and he's wondering if he's flying too cool and what he should do about it. Paul asks how far lean of peak he's flying. Adam thinks it's about 40 degrees, but at a fuel flow of 12.5 gallons per hour at an RPM of 2400. The hosts agree he's flying very lean. They recommend he try to fly about a gallon per hour more, which will get him a lot more speed and more normal temperatures.

Carbon monoxide, kickbacks, avionics upgrades, and leaning radials are on tap. Email [email protected] for a chance to be on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Bill has a Cessna 210 and in climb he gets 50-100 ppm on his CO gauge. When he levels and goes lean of peak it goes back to normal. He's also noticed that if he puts the heat on he also doesn't have a high reading on his gauge. It's not from a hole in the firewall, Paul says. The most common places it can come in are from the header tanks where they come in through the belly, the steering boots on the nose gear, the down-lock boots on the main gear down-locks, the pilot's cabin door (look for light in the lower left corner of the door for light while in flight). The level goes down when he turns on the heat because he's pressurizing the cabin, which keeps the CO draft out. And he doesn't get it at LOP because he doesn't have nearly as much un-combusted fuel in this state, the driver of CO. Bob has a Cessna 182 and it has a North Point (nee P-Ponk) engine with an MT prop and experienced a kickback during start. He's wondering how to move forward. His mechanic recommended removing one of the impulse couplings (he has two). The kickback would occur if one of them didn't activate properly, Paul said. If the ignition fires early during the start process, the impulse coupling delays the spark until top dead center. If it fails, it doesn't delay it, and the kickback occurs. When the kickback happens, the nylon gears in the mags are stressed, the spring in the starter adapter can break. The hosts recommend changing that and inspecting the impulse coupling. The hosts gristle when Bob mentioned the MT prop. It's so much lighter than aluminum, and they result in many more kickbacks. Kyle is wondering about the leaning philosophy on the R-985 engine on the Beaver he flies. The manual cautions against leaning below 5,000 feet, and he's wondering what the hosts think. Colleen said since it's his employer's airplane and there's no engine monitor in the Beaver to just keep it full rich as directed. Mike said he might fly it in cruise just like a typical 4-cylinder and lean to the onset of roughness and enrichen it only until smooth again. Erick is looking at purchasing a Columbia 400 with legacy avionics and he's thinking ahead to potential long-term maintenance issues. The hosts explain the potential repair, maintenance, and replacement options. These include the Avidyne yearly maintenance fee he can choose to do with Avidyne, or he could install Garmin, which is STC'd. The MFD has an AD to replace the battery after 10 years.