”Let us know how the exorcism goes”

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 podcasts@aopa.org 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.