Jul 17 1980
From The Space Library
The Washington Star reported that discovery of a "serious potential safety defect" in the nation's most widely used jet engine had led the FAA to order mandatory inspections for two-thirds of the short- and medium-range commercial jetliners in the United States. The engine was standard on three major planes: the medium-range Boeing 727, with three engines, and two short-range planes with two engines each, the Boeing 737 and the McDonnell Douglas DC-9. Each FAA-ordered inspection on a Pratt & Whitney JT8D engine would take 170 hours to disassemble it to the point where it could be checked. Some of the engines were nearly new; others had been serving for several years: a JT8D would normally be retired after 20,000 cycles in service.
When a Hawaiian Airline DC-9 blew up on takeoff at Honolulu June 15, FAA inspection revealed that a portion of the engine was subject to metal fatigue and failure because of the factory machining of the metal. No serious injuries occurred in the Hawaii incident. However, random FAA checking showed that other planes equipped with JT8D engines had cracks in the same engine spot as the Hawaii plane. The potential flaw in the engines was the eighth compressor hub, a 591-pound wheel with an array of blades located in the middle of the 3,000- to 4,000 pound engine. Each engine had 13 compressor hubs, each with a successively smaller set of fans to collect air and force it through smaller areas into the fuel-combustion chamber. Machining of a flange on the eighth compressor hub was ground against the grain of the metal, putting unusual strain on that part. FAA spokesman Dennis Feldman could not estimate the cost of the inspection programs, thought to be in tens of millions of dollars; nor could he give any definitive answer as to whether the manufacturer or the airline would have to cover the cost. (W Star, July 17/80, A-1)
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