Ask the A&Ps

AOPA

Experts Mike Busch, Paul New, and Colleen Sterling answer your toughest aviation maintenance questions. Submit questions to podcasts@aopa.org. New episodes are released the first and fifteenth of every month.

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20 episodes
Updated Yesterday

Episodes20

Newest first

"We're in the twenty-first century here folks"
Oil insights, lean of peak with a carb, burning oil, and turbo advice
Yesterday · 45 min
"Your mechanic feels worse than you do"
Fuel flow problems, water in the oil, safety wire alternatives, and octane ratings
July 15 · 48 min
"It's in your head"
Warm cylinders, cold cylinders, and pressurized mags
July 1 · 52 min
"I always try to buy high and sell low"
Carbon monoxide, kickbacks, avionics upgrades, and leaning radials
June 15 · 49 min
"Too much data is a bad thing"
Bad intake valves and camshafts, shock cooling, and AD compliance
June 1 · 50 min
"TBO is not a reason to do anything to an engine"
Dirt daubers, creeping EGTs, and cloths in wheel wells
May 15 · 57 min
"If you lose a cylinder in your Cessna 150 you are down on a road somewhere"
Sticky valves, A&P currency, and sleepy cylinders
May 1 · 50 min
"Am I doing anything evil?"
Leaning, overhauls, and ignoring borescope images
April 15 · 57 min
"That installation is fraught with peril"
How much should a mechanic tell a client during an annual? Mike, Paul, and Colleen handle this question and more. Email podcasts@aopa.org for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full notes below: Justin flies a Twin Bonanza and cylinder 5 on his left engine takes as much as a minute to fire up and start running. It comes online fastest if he goes very lean quickly after starting. He's pulled the valve cover and springs off, and it's not a sticky valve, and he's reamed the valve guides. Mike wonders if it could be a primer problem. Justin disconnected the primer line, ran the boost pump, and checked for leakage and couldn't find any. Paul suggests taking the line off, capping off the injector, and then trying it. Jorg is trying to make sense of his data. He has a K35 in Austria and he has GAMI injectors and an engine monitor on his IO-470. He has a low CHT on the number 6 cylinder, and it's the first one to go on the lean side, and it shuts down first if they go very lean. An induction leak test seemed fine, and his GAMI spread is less than a gallon an hour. The valve was also lapped. Mike said a low probability culprit could be if the bleed air holes in the injector nozzle were plugged, since they don't seem to have an impact at wide open throttle, but would at a reduced throttle. Mark saw a Youtube video and is now wondering if there's danger lurking in the alternator. The video mentioned how an alternator elastomer coupler failure could lead to a catastrophic engine failure. Paul said the installation is critical because of some critical components. Mike thinks the video relies on old information. He said Continental used to employ a spring, which would come apart and throw large chunks of metal into the engine. The coupler is meant in part to protect the engine if the alternator seized, but sometimes the coupler would fail and cause its own failure. The newer versions have an elastic or rubber piece instead of a steel spring, which shouldn't cause an engine failure. Chaz is an A&P/IA and he wants the team to weigh in on the debate as to whether the inspector should give pilots a full list of squawks or only the airworthiness issues. He personally thinks he should give the whole list so the owner knows where he stands. The hosts agree that the full list is preferable. The mechanic is giving a full slate of options, and not a required list. Airworthiness items can be listed separately or be flagged.
April 1 · 53 min
"I'm an old mechanic and really like the idea of priming and painting"
Quick corrosion, long-lasting engines, and mobility mods are on tap for this episode. Email podcasts@aopa.org for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full episode notes below: Patrick is looking for the right fit on a potential aircraft purchase. He had a shoulder replacement and lost some mobility in his right shoulder. He’s wondering if he could get an accommodation on things like flap controls. Paul suggests he look for an older Cessna with the progressive flap switch, not the one with pre-selected detents. The hosts thing that up/down progressive switch would be a minor alteration and just a few wires. The pre-select flap lever is probably a major alteration and a lot of work because there’s a lot going on behind the panel. Jeff has a Maule M7 on floats and is battling corrosion. Recently he did a salt water landing, sat for about 3 hours in the water, flew home, and his left main gear didn’t rotate as he landed. He saw that the main forks had a bloom of corrosion that froze the wheel. He washed everything in fresh water, and then next day saw a bloom on the other gear as well. He is wondering if he had a stray current given how quickly it developed. Mike thinks it’s unlikely because if the battery if off it’s completely isolated from the rest of the system, meaning their shouldn’t be a way for the battery to provide electrical current anywhere on the airframe. Lindsay recently purchased a Piper Lance and wants to make sure she keeps the engine going as long as she can. They go over the basics and make sure she is boroscoping the cylinders, fly it regularly, etc. Mark is wondering how soon is too soon to put in cowl plugs after flying. He has a Cessna 206 and he’s wondering if he can put in the cowl plugs right away. The concern is about the plugs, not the engine, Paul said. The hosts all agree that he's fine to seal the cowl off as soon as he likes.
March 15 · 49 min
"That's an oft-reported myth"
Is going past TBO more expensive? Plus fuel vents and turbocharger temps. Email podcasts@aopa.org for a chance to get on the show. Join the world's largest aviation community at aopa.org/join Full episode notes below: Mike wonders if running past TBO actually costs more. He has a Mooney and has heard that overhauls far beyond TBO can cost more as a result of having to replace more parts. That is an oft-reported myth, Mike says. The only things that can cause an up charge on most field overhauls are having to replace the case or the crankshaft. Otherwise it’s a fixed price. Paul says the top engine generally goes into the trash. On the crankshaft, they usually just have to polish it or grind it. There’s no repairing a crankshaft. If it’s bad, it was bad because it had some other type of problem. You can go thousands of hours on crankshafts. Mike said Lycoming had a white paper on their website that said crankshafts are generally good for 14,000 hours. Cracks on the case can be welded. Mark has an early 182 and he’s having issues with the fuel caps properly venting. He has noticed that once you fill the tanks with cold fuel, there doesn’t appear to be an outflow vent. Paul said there’s a small weep hole that allows the expanded fuel to vent. But Mark’s tanks still aren’t venting. He pulled it out but didn’t seem to find a weep hole. He said it looks original and has an early Cessna part number. If the fuel is pouring out it needs to be replaced because the check valve is bad. The wing will balloon and can cause structural damage without a weep hole. He said when he removes the cap a big woosh of air will come out, indicating the fuel isn’t venting out as it expands. Jim is wondering how TIT and EGT intersect. He flies a turbo Saratoga and has been experimenting lean of peak and rich of peak. He’s noticed a significant difference between EGT and TIT. If the TIT is farther away from the engine, he’s wondering why it’s hotter than EGT. He’s also wondering how hot he can let the turbocharger get. Mike said TIT is hotter because the EGT probe is only seeing gas flow for less than a third of the time, and only when the exhaust valve is open. The EGT probe actually measures a “probe” temperature that averages the temps over time. When the gas gets to the TIT probe it’s a constant heat from all cylinders all the time. Redline on his TIT is 1,650 degrees, which Mike said is a continuous operation limit. Paul asked what the exhaust system is made of because that matters. He suggests not exceeding the red line. In cruise, the lower you can keep the TITs, the longer the system will last. Mike limits his TIT to 1,600.
March 1 · 49 min
“Is this like pulling a mattress tag off?”
Borescope primer, torque tales, manufacturer nonsense
February 15 · 54 min
"The owner can't do maintenance because the owner doesn't have arms"
A guide to owner maintenance, slipping starter adapters, and more
February 4 · 50 min
"You're going to give him nightmares"
Rust on new cylinders, creative leaning, manifold issues
January 15 · 56 min
"He has a piston with a smiley face on it that's not very happy"
How many hours are too many?
January 1 · 42 min
"Just be sure you lube it with something"
Wood wings, generators, and pre-emptive engine overhauls
Dec 15, 2025 · 44 min
"If you go to 76 percent, the wings will fall off"
Electronic ignition, creative mods, lean of peak
Dec 1, 2025 · 51 min
"It's one of the few accidents where you get to choose where it happens"
Fuel indication problems, high oil temps, gear motors, and corrosion
Nov 15, 2025 · 52 min
"Being an aircraft owner is the hardest job in aviation"
Spark plugs, aircraft records, lean of peak, and circuit breakers
Nov 1, 2025 · 51 min
"That's an urban legend"
Keeping cool (and warm), plus oil composition and lean of peak
Oct 15, 2025 · 49 min

Ask the A&Ps

"We're in the twenty-first century here folks"

"Your mechanic feels worse than you do"

"It's in your head"

"I always try to buy high and sell low"

"Too much data is a bad thing"

"TBO is not a reason to do anything to an engine"

"If you lose a cylinder in your Cessna 150 you are down on a road somewhere"

"Am I doing anything evil?"

"That installation is fraught with peril"

"I'm an old mechanic and really like the idea of priming and painting"

"That's an oft-reported myth"

“Is this like pulling a mattress tag off?”

"The owner can't do maintenance because the owner doesn't have arms"

"You're going to give him nightmares"

"He has a piston with a smiley face on it that's not very happy"

"Just be sure you lube it with something"

"If you go to 76 percent, the wings will fall off"

"It's one of the few accidents where you get to choose where it happens"

"Being an aircraft owner is the hardest job in aviation"

"That's an urban legend"