Air Crash Site
Probable Cause of the Crashes of the Lockheed Electra
[The following information was related in February 1996 by Orville Newall, a 12-year veteran of the United States Air Force and Reserve. His assignment was in one of the first units of rescue teams at an air disaster. One of the training films included this description.]
After no satisfactory explanation for the cause of the crashes Lockheed decided upon this test: An Electra was completely submerged in a large tank of water, the reason being that difference in air pressure between the cabin and exterior at 30,000 feet could better be controlled. Hundreds of small motors were connected by cables to different parts of the fuselage and wings so as to simulate the vibration stress of the plane in flight.
Many hours of vibration finally led to metal fatigue between rivit holes of the mounting of a window in the cabin. When the window gave way and blew out like the tearing of a postage stamp, the plane began tearing apart.