Aviation: Electro's Second Take-Off

"The Electra's O.K." So said Federal Aviation Agency Chief Elwood R. Quesada last week as he lifted the 259-mile-an-hour speed restriction he had imposed on the plane nearly a year ago after two crashes took 97 lives. The FAA had taken improved Electras, their engine mounts and wings strengthened to eliminate the gyroscopic resonance (i.e., vibration) that had torn the wings off two planes, and then put them through spins and power dives in what Quesada called "probably the toughest flight check yet."

While FAA inspectors looked on, the Electra's builder, Lockheed Aircraft Corp., had its test pilots put the plane through 100 hours of landings, take-offs and dives. In the most severe test, an engine mount was deliberately weakened to test the margin of safety. The pilots, wearing parachutes, put the plane into a 418-mile-an-hour power dive, but the fatal vibration never showed up.

So far, American Airlines has received three modified Electras and Eastern one. By summer Lockheed says all 165 planes in service will be modified. The lines do not want to fly the modified Electras at top speed (400 m.p.h.) until their fleets are almost fully converted, to avoid disrupting schedules based on the slower speeds.