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.