THE HUMAN ERROR
TEFLON TAPE — FRIEND OR FOE?
BY GORDON DUPONT
Often seen as a friend when it helps stop a toilet line leak, it is one of a plumber’s best friends. However, Teflon®
tape can also be a deadly
enemy. Many are not aware (Lack of Awareness #23 May 2017 issue) just how dangerous using it can be. If you look at the picture in the top/ right corner of the cartoon you see a tiny piece of Teflon tape and an underwater Navajo in the bottom right of the small picture. The story starts with an AME
changing an oil line and fitting on the turbocharger controller on the left engine of that sunk aircraft. It had been weeping but he did NOT use Teflon tape on this installation. Someone else had likely used the tape to successfully stop a leak. What he did not notice on the later installation was the small pieces of that Teflon tape left down in the turbocharger controller threads. They are almost translucent and hidden in the bottom of the threads. As he installed the new
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fitting into the controller, it pushed those tiny pieces of Teflon into the controller. Being beyond the filter, they lie in wait to clog a vital orifice in the system at the worst possible moment.
The accident aircraft, a Piper
Navajo, was used by a company to fly loggers in and out of a remote logging camp. This particular logging camp had a 3,000 ft gravel airstrip located along the side of a river in the mountains. The mountains rose steeply on each side of this river making it a fly in up river to land and out down river to take off. There was no going around and once the pilot started up the river, he was committed to land. The regulatory body approved the landing strip on the condition that the pilot was in communication with a qualified person at the strip who would assure the pilot that the weather and the strip were clear for a landing. This was not a particularly
dangerous maneuver, but there was no margin for error. The flights were VFR only and used a single pilot as permitted by the regulations. The day of the accident was not ideal, but within VFR limits, and the pilot flew in without a problem. He unloaded the crew who were in for a two- week stay and loaded the lucky crew going home. Take off downstream was normal
but the pilot had no sooner retracted the landing gear when the left engine manifold pressure dropped from 42 inches take off boost to 28 inches. The heavily-loaded aircraft swung violently to the left to face a mountain side seconds ahead. With full right rudder and aileron they brushed past the trees as he hurriedly cranked in rudder and aileron trim in the narrow space now just over the river. Suddenly the left engine went from 28 inches up past 42 inches of boost to something like 52 inches, swinging the aircraft to now face the
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