The International Cessna^® 170 Association

I'm sure George will correct me if I've misquoted him but here goes. If we can use non-faa/pma parts for switches/fuses/bulbs, why do we need to use faa/pma solenoids?. This was posted somewhere in the forums but I cannot locate it so someone please catch me up on the comment.

Because actuators, relays, contactors, and solenoids were not specifically included in the FAA opinion. (Neither were the Tung-Sol and Wagner 4509 landing light lamps that are identical to the GE 4509's.... but that's the way the cookie crumbles. If you look at the IPC you'lll see that the light bulb for the cabin light is a Mazda part number, not a GE.)
The rule allowed replacement switches identical in mfr, fit, function, and part number to be used without the FAA-PMA notation. An example is a Potter and Brumsfeld W31-20 circuit-breaker/switch to replace the identical item in a Beechcraft Baron. The difference not in the switch, but in the source.... Spruce or Beech (or the local electronics supply.)

Non PMA'd parts like solenoids in other services (such as automotive) might look identical but may have significant differences. For example, the automotive vibrating voltage regulator may have a wire-wound resistor that is exposed to the elements, while the aircraft version is "potted" in heat sink, anti-vibration potting. The automotive version may fail in aircraft service more readily, or it may have a failure mode not deemed safe for aircraft use.

If you're talking about that starter solenoid, or that battery solenoid, ... I understand the reluctance to believe there's any actual difference. (I don't believe it myself. And I especially have little concern about that starter solenoid... if I can't start it I'm not going airborne with it anyways, and it's not likely to be used in-flight, either.) But the argument loses steam when the price is compared to the aviation sources. They cost virtually the same, as long as you avoid Aviall and certain other "premium" supply houses.

gahorn wrote:... If you look at the IPC you'lll see that the light bulb for the cabin light is a Mazda part number, not a GE....

In a recent discovery I found the following from a lamp supplier:

Mazda: On December 21, 1909, General Electric first used the name Mazda on their lamps. The name was trademarked and assigned the number 77,779 by the United States Patent and Trademarke Office. Today, we associate the name with automobiles, but when it was first used by GE it was chosen to represent the best that the American Lighting industry had to offer at the time, and it was selected due to the fact that Persian mythology gave the name Ahura Mazda to the god of light. General Electric dropped the Mazda trademark in 1945, and ceased licensing the name as well.

So, it appears that Mazda and G.E. are synonymous.

Yet more evidence they are the same company (although obviously a different lamp type):


Westinghouse apparently attempted to join the parade with a "Mazda-Lamps" nomenclature:

gahorn wrote:Non PMA'd parts like solenoids in other services (such as automotive) might look identical but may have significant differences. For example, the automotive vibrating voltage regulator may have a wire-wound resistor that is exposed to the elements, while the aircraft version is "potted" in heat sink, anti-vibration potting. The automotive version may fail in aircraft service more readily, or it may have a failure mode not deemed safe for aircraft use.

George is entirely correct on this one. I can speak from experience that when the exposed wire wound resistor on a (as it turned out, Cadillac) voltage regulator falls off and shorts out at night, the last light you see from the cockpit is a bright blue flash thru all the gaps in your cowl.