Safety Panel Urges Stricter 747 Wing Inspections

The National Transportation Safety Board urged the government Tuesday to order more frequent and rigorous inspections of wing-assembly units suspected in the crash of an El Al Boeing 747 cargo plane in Holland last month.

In a letter to the Federal Aviation Administration, the safety board said the investigation to date has not been able to pinpoint exactly why the fuse-pin assembly holding two engines to the aircraft’s wing separated during flight.

But the safety board said it is clear that more frequent inspections of the units are needed on all Boeing 747s. It said it supports actions already taken by the FAA and Boeing to examine the fuse-pin assemblies on the worldwide 747 fleet.

“However, the safety board believes that more stringent measures are needed to reassure the continued airworthiness of the Boeing 747 fleet,” the letter said.

The board said the inspections now required by the FAA are too infrequent. And it said there is no reason that engines manufactured by General Electric should be excluded as is now the case.

It urged the FAA to shorten the inspection cycle, require an ultrasonic rather than a visual inspection and begin inspecting GE engine assemblies. It also said the FAA should require Boeing to replace fuse pins that may be susceptible to corrosion or fatigue cracking with a newly designed fuse pin.

Fred Farrar, an FAA spokesman, said the safety board’s recommendations will receive “high priority consideration.”

The El Al cargo plane crashed into an apartment complex on Oct. 4, shortly after taking off from Schiphol Airport in Amsterdam. Fifty people on the ground were killed, as were the three-person crew and a passenger on board the aircraft.

The investigation to date has shown that the two right engines separated from the wing in flight. The safety board said an examination of the wreckage led to the discovery that parts of the fuse pin assemblies on the outboard engine were broken.

“It has not been determined whether the fracture resulted from impact loads, pre-existing corrosion or low-cycle, high-stress fatigue damage,” the safety board said.

Four of the steel fuse pins, each about 2 1/4 inches in diameter and four inches long, connect each engine strut to the wing. The engines are bolted to the struts. The pins are designed to give way if an engine seizes up, to allow an engine assembly to fall away rather than tear up the wing.