Making new parts, protecting parts, replacing parts, and identifying bad parts is the theme of this month's episode. Plus, a spirited discussion on fuel selectors. Send your questions to podcasts@aopa.org for a chance to be on the show.

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Greg is building an RV-10, and he’s wondering if he should prime all the skins while he builds to ensure there’s good protection inside and out. Mike, Paul, and Colleen disagree on what to do. Paul thinks he should skip the priming and instead spray Boeshield or AV-8 because you can spray it on after the airplane is built. It’s a one-time application. Mike thinks if Cessnas have lasted for decades without being primed, Greg should be ok as well. And Colleen is on the fence. Bottom line: there’s no right answer, just the right answer for each builder.
Russ is trying to help a friend. His 182R lower door hinge is cracked and the mechanic isn’t any help. Russ owns a machine shop and thinks he can manufacture the part. Mike says that it is important not to create a part that is better than the original. He must create an equal part. Something better would require additional approvals. Paul says it’s important to get the mechanic involved early because he will assume the greatest liability, and must be comfortable installing the owner-produced part. And many mechanics aren’t comfortable installing something without a part number. All agree that the hardest part of making the part will be figuring out exactly what the original material is and how it was made.
Frank wants to use a synthetic oil in his 182 because he’s had such good results in his car. Mike makes the point that there’s no full synthetic oil on the market. He suggests 15w50, a semi-synthetic, but only because Frank is able to regularly run mogas. Those who only run with 100LL shouldn’t use a semi-synthetic, Mike said.
Ryan is part of a flying club and they have a Cherokee 140 with an intermittent landing light. He was able to get the light to work regularly by applying a bit of heat to the circuit breaker, which makes him think the breaker is bad. The hosts recommended buying his own breaker and asking the mechanic to replace it. It’s a relatively easy fix. They recommend going to a pull breaker instead.
Ernest said his mechanic hears a knock, but the hosts all agree that the video clearly sounds like lifter clatter. Mike say to look left, look right, make sure no one is around and pour in some Marvel Mystery Oil, which can reduce lifter clatter. When the lifter doesn’t fully lift there is play in the valve train, which makes the noise. Cleaning the lifter is an option, but it is a lot of work. Paul thinks it’s possible it only happens at lower oil pressures. With normal oil temperatures he should have 80 psi oil pressure at cruise, and not something lower, like 65.
Alex sparked a spirited discussion on pilot technique. He’s wondering about how to test fuel flow on the ground. Some airplanes call for changing tanks on the ground, others don’t. Colleen thinks it’s ill-advised to switch tanks during the run-up. Paul said the fuel bowl on many carbureted engines contain about 30 seconds of fuel at cruise power. He said you’ll never run the engine long enough on the second tank to properly test it. This led to a long discussion about Cessna’s fuel selector design. Mike said he never moved the fuel selector off of Both in his 182, and furthermore he doesn’t understand why Cessna even made it. While the Cardinal will drain from the selected tank, the 182 doesn’t work the same way. If you burn off the right tank, for example, the fuel will be replaced with fuel from the left tank, and not air. Paul said he would stay on Both if he could. They then debate whether to use the fuel pump when switching tanks, and for many reasons Paul recommends sticking to the POH.