Avsnitt

  • A Vans customer wonders what to do next, and a 172 pilot asks if carb heat is really necessary all the way to the ground. Plus, the best spark plugs, and a vexing gear issue are on tap for Mike, Paul, and Collen this time. Email [email protected] to be on the show.

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    Full notes below:
    Greg has a kit from Vans on order and he’s wondering what to do next. He can replace his quick build wing kit with the small cracks installed, but he wants to know if he should order replacements. Paul said when sheet metal work is done on certified aircraft in the field, a lot of cracks naturally come up. Greg said a customer has to agree to accept the modified terms of the new contract, and you have to either accept what they send you, or spend money on a second kit. Paul said to deburr as little as possible. The goal is clean, sharp corners, not a knife edge that can cut the rivet. Just barely touch the hole, he said.

    Travis has an unusual gear problem. He was tasked with ferrying a Wheeler Express RG, an unusual experimental. On the ground the gear works perfectly, but when flying it won’t reliably retract. The system is based on a Glasair 3, and Colleen said the Glasair racers have a similar experience with their airplanes at Reno. On a ferry flight the hydraulic fluid built pressure over a few hours, and Travis had to select the gear down lever in order to release the pressure. Paul said not to spend any more time on the system, and replace it with something from Cessna.

    Brian wants to get to the bottom of the fine wire and massive plug choice. His shop said he had to replace all 12 fine wire plugs at the last annual, all with around 800 hours on them. The shop recommended Temptest massives, which is what he did. He’s wondering if there’s really a difference in performance. Paul said fine wires tend to idle a little better and smoother. Corrosion was an issue on older Champion fine wires, which is what Brian had. And the ceramic is thicker on Tempest. Fine wires also last longer, usually long enough to cover the additional cost. Mike said they cost about four times as much, but last four times as long. He said some people also report smoother operation at very lean mixtures and small fuel economy improvements. Colleen has fine wire Tempests in her Cardinal but massives in her Skybolt. Her fine wires run a bit cleaner and don’t need to be gapped. Brian has seen a larger EGT differential when flying lean of peak with the massives.

    Dennis has a 172 and he wants to know if it’s really necessary to keep carb heat on all the way to the ground. Mike said a newer Lycoming Skyhawk is less susceptible to carb ice, but his Continental O-300 is much more likely to produce ice. He recommends installing a carb heat gauge if he really wants to avoid having the carb heat on longer than necessary.

  • This episode Mike, Paul, and Colleen help an owner with an engine that randomly dies after 2100 rpm. Plus, the role of avgas as a lubricant, prop governor issues, and getting back into maintenance. Email your question to [email protected] for a chance to be on the show.

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    Full notes below:
    Dennis has a Cardinal RG with a prop governor issue. When it’s warm, the prop underspeeds just a little. He’s done a bunch of troubleshooting, and he is at a loss. The manufacturer said to send his prop in, but he is reluctant to do that given how often prop shops deem them unfit for continued service. Dennis is an A&P and he asks if he is allowed to open up the governor and work on it. Mike said he doesn’t advise it because he both can’t do it legally and doesn’t have the right tools. Both Paul and Colleen said their props do the same thing, and they recommend he crank up the rpm just a little since a small amount of overspeed is allowed under the type design.

    Luis is looking to get back into aviation maintenance after earning an A&P many years ago. The hosts debate the FAR, which says that a mechanic is current if the Administrator deems he or she so, or if the mechanic has served as a technician for the past six months. The hosts think Luis should use the preventative maintenance provisions to do the work without supervision.

    Jeff built an airplane with a PZL Franklin 235 and the engine won’t make full power. The static rpm is 2800, and anything beyond 2100 kills the engine. He thinks either his homemade exhaust is causing too much back pressure, or there was a manufacturing issue. He wonders if there’s a way to isolate the problem. The ignition timing is set to 32 degrees, which is the manufacturer spec. Mike and Paul recommend backing off the timing first to see what happens. Paul suggests he could also remove part of the exhaust to see what happens.

    Josh wonders if we are too eager to get off avgas, specifically because of its proprieties as a lubricant. He’s always heard that it lubricates valves, but Mike thinks it’s probably not a concern. It’s true that before valve seats were hardened, there was some microwelding, which led to valve seat recession. Lycoming switched to hardened valve seats in the 90s, and Continental switched in the early 2000s. There is a possibility that some of the older Continental cylinders could have problems with valve recession, but it's too early to tell. He details the work that AOPA is doing with the dual-fuel Baron, which is seeking to understand some of these issues.

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  • 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.
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    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.

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    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.
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    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.
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    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.
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    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.

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    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.