Shake and Bake: The Beneficial Use of Exemplar Testing to Evaluate the Failure Mechanism of an Engine Component in a Small Plane Crash

A Ted Smith Aerostar twin engine plane crashed during a landing approach at a small airport in Vermont. The NTSB found no pre-impact mechanical issues that would have caused the crash.

In litigation arising from the accident, it was alleged that one of the engines fuel servos, which meter fuel to the engine, malfunctioned. Specifically, it was suggested that a small, electroless nickel alloy bellows sustained a fatigue failure inflight allowing unmetered fuel to enter the engine causing power loss contributing to the crash. ESi’s investigation included exemplar servo bellows testing that permitted a comparative fractographic analysis of the results with the subject bellow’s fracture. The project highlighted the benefit of exemplar testing to understand the post-crash fire exposed condition of the specialized alloy bellows component.