Chris is trying to make sense of his logbooks. He has a Cessna 172 RG and he and his partners had a few electrical issues recently. Some of the logbook entries went in the airframe book and some went in the engine logbook, and he’s wondering about the decision-making process involved in picking the proper logbook. Mike said there’s no requirements around which

entry to put in which logbook, and in fact, there’s no requirement to have a logbook in the first place. It’s easier and retains the value of the aircraft, of course, but the need to keep a specific logbook isn’t based on regulation. The reason we use different logbooks, he said, is because if we were ever to sell the engine separately from the airplane, it would be nice to be able to

include the record in the sale. If the item would move with the engine, put it in the engine logbook. Paul said his shop only puts the annual inspection in one logbook, and typically that’s in the airframe book.

Brandon has a 1977 Cessna 182Q with a low-time engine. Every time he borescopes it he sees lots of lead buildup on the valve stems of the cooler cylinders. He’s wondering if there’s a way to run it hotter, or is there something he can add to the fuel. The hosts agree that it’s actually a mixture distribution issue, something normal and expected in the O-470. Paul had a 182 and

he did a bunch of lean testing. When he would lean to roughness and roll it back only enough to smooth out the engine, he would have two cylinders lean of peak, two at peak, and two rich of peak. Mike suggests adding TCP to the fuel. The main downside is that it’s quite toxic, so careful handling is required.

Scott is interested in pushing the boundaries of the maintenance regulations. He’s wondering if he is allowed to sign off an AD as an owner because the regs don’t specifically state it has to be a mechanic. Mike thinks it must be an A&P because they are inspections, and only A&Ps can do

inspections. There are a few ADs that explicitly allow the owner/operator to perform them. Paul suggests that a lot of ADs require a maintenance action that is outside the scope of owner-performed maintenance as well.

Mike is questioning Continental’s guidance that limits extended running below 2,300 rpm. He finds that his airplane runs smoothest at 2,100 rpm. Mike explains that the bulletin came about after an issue with Cape Air and their 402s. After a few in-flight engine failures, they grounded the fleet and started inspecting engines. The failures were caused by counterweight release with accelerated wear in the pins and bushings. Continental couldn’t find anything wrong with the parts, and they guessed that it was due to operation at low rpm. Cape Air was operating at high power, rich of peak. They never tracked down the real problem, and guessed this was the issue. Cape Air had gone from operating at 2,300 rpm to 2,200 rpm. Mike believes that if you are operating at high power and rich of peak, it might be worth observing the limit, but if you are

operating at low power, or lean of peak, you can ignore it.