On August 30, 1986, a Great Lakes 2T-1A-2 (registration N6198L) was involved in an aviation accident near Houston, TX. Investigators recorded the probable cause as: The ends of the outer string and the inner reinforcing wire of the engine air intake duct were not properly positioned under the duct clamp during installation. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Improper positioning of air intake duct components caused unwinding, duct collapse, loss of engine power, and a subsequent stall during an attempted return, resulting in impact with terrain.
Incident Overview
An aircraft experienced a loss of engine power following a failure of the engine air intake duct. The duct's structural integrity was compromised due to incorrect installation of its components.
Mechanical Failure
During installation, the ends of the outer string and the inner reinforcing wire of the engine air intake duct were not properly positioned under the duct clamp. This allowed them to unwind during engine operation, moving out of their normal positions on and in the duct. Consequently, the duct wall lost its rigidity and collapsed, leading to a loss of engine intake air and subsequent power failure.
Pilot Actions and Result
The pilot attempted to return to the airport while at an altitude of only 100 feet. During the turn, the aircraft stalled, and there was insufficient altitude to recover before impact occurred.
Probable cause
The ends of the outer string and the inner reinforcing wire of the engine air intake duct were not properly positioned under the duct clamp during installation.