Reader Feedback

More GA Info Please

I have picked up Aviation Maintenance off and on now since it was first published. Every once in a while there is information about the smaller general aviation aircraft. I have been working on these type of aircraft for 28 years. I have learned a lot over the years by just figuring out problems during routine maintenance or performing annual inspections, which as an IA, I average 45 annuals a year. But, it would be nice to see your magazine add more for technicians like me to help us in our field. It seems to me that information on larger aircraft fills the pages more often than for us little guys. Our customers don’t own big corporations and they don’t care to own big aircraft, they still enjoy getting behind the yoke themselves. Working with owners like this and dealing with them one on one, we form a friendship. They trust our work, professionalism and attention to detail. Any information about Pipers, Cessnas, Beechcrafts, Lycomings, Continentals, etc. would help.

Mike Everhart

Winter Garden, Florida

Smoke in the Cockpit

There is a dangerous human factor cycle that can not be broken. Case in point: a pilot flying a helicopter reported smoke in the cockpit and made a precautionary landing. A mechanic was dispatched to determine the cause. The problem could not be duplicated so the aircraft continued its mission. The next day the aircraft was brought in for a scheduled major inspection. During that inspection the air conditioning condenser blower motor was found to have brushes worn beyond limits and the rear evaporator motor brushes were worn beyond limits and that motor is wired with a hi/low switch in the cockpit. Keep these brushes in mind as this story progresses. This aircraft came into inspection with a malfunction in a different system that caused me to open up the main airframe wire bundle. Not finding anything there, my search continued by dropping the overhead interior in the cockpit area to investigate the wire bundle there. Oh my! The connection used at the evaporator hi/low switch was a burnt melted ball. I checked the dropping resistor for the hi/low switch and the terminals were black and melted. The designed circuit breaker for this system is 20 amps. Here, now, is the dangerous aviation cycle that cannot be broken. I take this situation to the maintenance supervisor who does not have a strong electrical knowledge. The supervisor calls the manufacturer of this system and the customer relations person tells us this, "We have tested this system several times and it is okay as designed. You must have a bad ground somewhere, maybe some corrosion or something." Think about that statement for a moment. What the heck do you think motor brushes do? As carbon brushes wear down they coat the commutator. This increases the resistance and the heat from this action is directly proportional to the increasing resistance. With a 20 amp breaker you will start melting wire insulation anytime after about 10 amps; but the maintenance supervisor believes what the manufacturer is telling him. This is very serious, so you send off a report to the local FAA FSDO. Yup, here comes the newest FAA safety inspector in the office to talk to the maintenance supervisor, not to you. He never looks at the aircraft because the maintenance supervisor has passed on to the safety inspector that there is something one of his mechanics has overlooked and that the system (of which the FAA gave the STC blessing to) is good as per his conversation with the manufacturer. This is the everyday cycle in aviation, and that folks is why aviation is crashing.

Name withheld