A new client had a problem with their aircraft’s elevator trim. The trim indicator seemed to be stuck, even though the rest of the trim system seemed to operate normally. A short search found the root cause of the problem, someone had used a makeshift and illegal part to connect the elevator trim transmitter to the tab.
On the left is the correct part, an MS20392-1C11 Cadmium plated steel pin. On the right is the culprit, a standard AN470 aluminum rivet which was hand drilled to accept a cotter pin as a safety lock. This oversize hole coupled with a steel cotter pin caused the thin aluminum side walls to let go, releasing the trim transmitter arm, thus no indication in the cockpit.
This is not the first, nor the last time I will find someone else’s laziness as the cause of what could have been a catastrophic failure. If the autopilot was engaged, the error in the trim reading could have caused a steep nose up or down attitude which could have ended in flames. Bogus parts are a plague on the aviation industry, and I am surprised at how often I find this stuff. Someone had the nerve to put other peoples lives at stake because they didn’t have the correct part available, or were to cheap to order the correct part.
I could MABEY see using this as a last ditch effort to limp an airplane home on a ferry permit from the bush where parts are not easily obtainable, informing the pilots of the potential problem, with the intent to install the correct part once home. BUT, this was not the case for our client. Someone who worked on the aircraft before us, left a deadly trap on this airplane.