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.