Extreme Evidence

"Wing Failure"

Last Monday night, I took the evening off and happened to watch the TV show “Extreme Evidence”.  The cases presented involved in-flight “wing off” failure on three Lockheed Hercules C130 aircraft that were being used to fight forest fires in California and Colorado.  In two of the incidents, a video tape was recording the fire retardant drop and inadvertently caught the wing failures and resulting crashes.  Thus, the investigators had real time accident videos.  The NTSB investigators concluded that wing failures and the ensuing crashes were the result of fatigue crack propagation in the wing support structure beneath a wing stiffener.

When I saw the reconstruction and SEM results indicating fatigue cracks in the wings, I had a “flashback”.  In 1976 or 1977 an associate was hired to investigate a Lockheed L382 (non-military version of the Hercules C-130) wing failure that occurred upon landing at Ice Island, Alaska. 

Upon a somewhat hard, but not unusually so, landing the subject aircraft lost a wing.   The freight hauler was suing the University of Alaska for supposedly improperly maintaining the runway.  Our SEM studies and metallurgical failure analysis indicated that the wings contained large fatigue cracks and the “hard” landing merely provided the straw that drove an existing fatigue crack to final failure and the aircraft's wing separated.

Incidentally, at about the same time a Hercules C-130 lost a wing upon landing at Will Rogers Airport in Oklahoma City, OK.  This incident was also recorded on video tape.

The lesson here is, maybe we should try harder to “learn from our failures.”  If accidents and metallurgical failures are promptly and properly analyzed and the results completely evaluated future catastrophic incidents might be avoided.