Experts Mike Busch, Paul New, and Colleen Sterling answer your toughest aviation maintenance questions. Submit questions to firstname.lastname@example.org. New episodes are released the first of every month.
"Compression readings are garbage"
1:01:00This 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@example.com 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 Detailed notes: Phillip is trying to track down radio gremlins in his Citabria. The hosts suggest putting in a larger grounding plane, which will require some fabric work. They also say the connections to the grounding plane should be cleaned. Brad is wondering how reliable our engines are. Mike makes the point that complete power loss events not related to fuel issues are rare. This is because cylinder problems are the most common, and they usually don't cause a complete power loss. Colleen referenced the Nall report, which details about 10 accidents a year due to power loss events. https://www.aopa.org/training-and-safety/air-safety-institute/accident-analysis/joseph-t-nall-report Gary is thinking about overhauling the engine on his Cessna turbo 210. The hosts say lower compressions aren't necessarily a reason to overhaul an engine. Indications like certain case cracks and oil analysis are more reliable markers of when it's time to overhaul. Mark wants to know how to manage maintenance risks on his club aircraft. The best thing someone can do is avoid maintenance unless it's necessary, he's told. Mike, Paul, and Colleen are big believers of doing maintenance on condition only. Ryan is wondering where the fuel is going in his 182. He used lean find on his engine monitor and got 14 gallons per hour at 9,500 feet and 2100 rpm. Mike examined the engine monitor data on the Savvy Analysis platform and found that Ryan never reached peak EGT when leaning. The hosts suggest leaning to the onset of roughness and increasing the mixture slightly until it smooths out. Colleen uses lean find, but she doesn't find it very reliable.
"Why can't we do something simple like clone an engine?"
48:59This 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 firstname.lastname@example.org 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 Detailed notes: In the intro Colleen references a Lycoming service instruction on cleaning cylinders with walnut shells. Google "Lycoming Service Instruction 1418" to see it. John asks about increasing compressions. They’ve been going up for 5 years, despite being over TBO time. The compression test is a terrible test, says Mike. Mike references a Continental graph of compression tests over 300 hours. Paul wonders why aircraft engines are so expensive and why we can’t just clone them to make them cheaper. Mike suggests there are three elements that create high prices on aircraft engines—the high cost of certification, low production numbers, and the high cost of liability insurance. Abdullah asks what aircraft cleaners are effective and safe. Paul recommends Dawn dishwashing soap as a cleaner and degreaser. GoJo hand cleaner without the pumice also works well. He doesn’t recommend using a pressure washer because you are likely to wash away paint, and push particulate in between skins. Colleen and Mike both use Simple Green aircraft cleaner. Bob’s LongEZ has engine roughness only at 2,500 rpm. Colleen references the carburetor manufacturer's website and a troubleshooting guide, found here: https://msacarbs.com/carburetor-troubleshooting/ Mike suggests Bob do a series of mixture sweeps at 2,500 rpm to see the data. Paul suggests that it might be a problem in the mechanical linkage. Robert asks simply what he’s supposed to do with the split master switch. The switch enables the pilot to isolate the alternator. Although some recommend leaving the alternator off during the start to reduce load on the battery during the starting sequence, Paul, Mike, and Colleen don’t think it generally matters. Mike thinks there are only two times to consider starting with the alternator off. One is when using a depleted battery, and the other is when using ground power during the start.
"There's no free lunch in aviation"
43:00Broken 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@example.com Jeffrey had a 1964 172 with an engine miss and a stuck open exhaust valve on his number 4 cylinder. Unfortunately, the rocker arm subsequently broke. How do I keep it from happening again, he asks? Paul advised that he would want to check the wobble on the other valves. Mike reminds Jeffrey, an A&P, that you don’t have to remove a cylinder to ream the valve guides. Paul suggests reading an article on his website that explains the wobble test. (https://www.tennesseeaircraft.net/2007/12/15/lycoming-exhaust-valve-a-sticky-situation/). He said a wobble test will tell you if the valve guide has bell-mouthed or if there’s too much material that collected on the guide that cinches down on the valve, which is usually what happens. Charlie asks whether there are downsides to flying oversquare. Mike, Paul, and Colleen recommend he check the engine operator’s manual from Lycoming, which will give detailed information on acceptable rpm and manifold combinations, including many oversquare options. Michael has Mooney and is experimenting with a borescope. He was wondering what happens if you find oil in the cylinder, as he has in 3 of his 4 cylinders. Mike says so long as he doesn’t have spark plug fouling not to worry about it, and he relates that in his Cessna 310, whose engines are slightly canted because of the dihedral, he always finds oil in the lower engines. Colleen said if Michael is having trouble starting the engine or if he sees lots of smoke he may need to address it. Todd is building an RV-14 and is curious about a crankcase vacuum kit in order to have a cleaner belly and maybe gain a few horsepower. Mike, Paul, and Colleen are dubious of the claims, and Mike says he wants to know if the engine is blowing oil out the breather tube. Nate is wondering whether overhauling his Cessna 182’s engine was a good idea. After discovering metal shards in the valve cover, he decided to go forward with an overhaul. Paul said you don’t learn much more from pulling a cylinder than you would from a borescope. Mike, Paul, and Colleen agree that significant metal in the valve cover likely came from the springs because there’s no other way for the metal to get in that area.
"An oil filter inspection is non-invasive, unless you're an oil filter"
49:41A 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 firstname.lastname@example.org
"About the half the time, reported cracked cylinders aren't cracked"
50:09This 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@example.com
"Heavy detonation is normally a self-correcting event"
42:13This 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 firstname.lastname@example.org
"I don't see anything that makes me want to attack the engine with tools"
53:26This 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@example.com.
'If it moves, squirt it with something'
45:58This 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.
'We just saved your engine'
49:29This 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 firstname.lastname@example.org
"Did you float the dog?"
55:58This 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@example.com