I have been a Professional aircraft mechanic for thirty six years. I have run shops with 16 technicians at a time. I made sure that each new hire learned to do 500 hour Inspections on Magnetos and Alternators. With each individual I would go through each Magneto Type or Alternator that we would inspect. I did this because it was at the time the most cost effective way to assign work. The last pace I worked for 17 ½ years had 49 charter, lease back and rental aircraft with every type of ignition system that was made be it Bendix or Slick Eiesmen Case tractor & some real weird mags on a TD9 Caterpillar tractor. Needles to say I have formed many opinions over the years. Most of which no one listens to and my opinions have changed over the years.
Eventually I hired a full time accessory over haul guy. It was cost effective because he could do three mags to one of my line mechanics. We replace all hardware screws, & seals on each 500 hour inspection. Why because the lock washers loose there tension and then the screws back out with vibration even if the torque was set properly. It cost about $2000 dollars annually to Certify all of the shops as well as the individual mechanics torque wrenches which I paid for. This insured that all work would meet standards. I ca tell you most shops will not pay to have there mechanics torque wrenches certified. We had many specialty Torque wrenches such as the one torque screw driver we had just for Magnetos.
I have had brand new Impulse couplings break springs after only 50 hours of operation in both Bendix & Slick mags. Bendix Mags do put out more spark energy. This is generally because of the larger coils I assume. I do not care because both mags run well in the application to which they are applied as long as they are maintained properly. That is not to say that I do not prefer one mag over another. I Like Slick Mags particularly for the ease of maintenance. They are easy for the average technician (Read Mechanic) to learn to repair and troubleshoot. The entire Mag family follows the same design. However I prefer the large Bodied Bendix mags and shower of sparks ignition in high altitude flying airplanes. Preferably with the Mags pressurized. Such an installation might be in a Cessna 340 or 421. Ram aircraft supplies pressurized slick mags with there Ram converted engines. They like them well. I do not. The vents on the mags plug with carbon about every fifty hours and it can not be cleaned with out removing the mag. They need to be removed about every 200 per service instructions to have an internal inspection. I can tell you if it is not done you will be purchasing a new mag at the 500 hour because the inside of the mag will look like it came off of the Titanic off of the bottom of the ocean. Large bodied pressurized Bendix mags do not have this issue. I could go on as to why but will not here.
The reason I say all of this is because from all of these issues people form generalized opinions about mags. This often leads to generalized statements that can be misleading about one product line or another.
So I will make some generalized statements that might be misleading:
• A few years ago Bendix came out with a service bulletin that lead to an AD. It required that the Coils be replaced. At the time Slick was offering a trade in allowance (Trading in Bendix mags) that made the purchase very cost effective. A lot of people switched to Slick mags.
• Part of the reason for this is because in either case of Slick or Bendix mags if three major parts such as a Distributor block, coil, and bearings had to be replaced with labor included you quickly exceed the purchase price of a new mag.
• Most mags do not need to have all of these parts replaced at a 500 hour inspection in most cases. So it is generally cost effective to do a 500 hour inspection on a mag. If you follow the 500 hour inspection and only the 500 hour inspection guide lines.
• If a technician spends the time to do a 500 hour inspection and the mag ends up being replaced. Then the profit price of the new mag will not cover the labor spent inspecting the first mag. It is easier and more cost effective to just replace it. But you do not know that going in. I try to explain all of this up front to a customer. But it still does not always help
• Customers do not like paying to have one mag inspected at a great cost and then have it replaced at an equal or similar cost. And have to pay for both.
• Most auto parts are marked up 200 % at the dealer and service shops. Most aircraft parts are only marked up 15 to 25 % at shops. They are still costly. Most owners squeal.
• I do not run that business any more it is to stressful.
• On my airplane I have Bendix Mags which are freshly overhauled. I know how and have the tools to overhaul Bendix mags. I have done lots of them 100’s. I had my friend and previous employee overhaul my mags for me. He has his own business now. Magnetos Inc. I bought the parts he did not charge me for labor. It still cost me nearly $500 in parts. Why did I rebuild the mags? Because I trust Cliff, I know what’s in the Mags. They were what were already installed on the aircraft. I have had brand new mags fail internally and destroy an engine. If I had had slick mags I would have kept slicks.
• I would not make a general sort of statement that because a mechanic does not do mags that he does not know what he is doing
And you thought George was long winded.
Jim
