The Federal Aviation Administration yesterday ordered U.S. airlines to inspect the engine mounts on models of the 747 jumbo jet similar to the one which lost two engines and slammed into a Dutch apartment building Sunday.
The order, called an airworthiness directive, is the latest sign that safety experts are concerned that a 4-inch-long and 2 1/4 -inch-wide steel part called a "fuse pin" may have played a part in the crash of an El Al 747-200F freighter in Amsterdam.
An FAA spokesman said authorities have no proof the fuse pin played any role in the crash, which left as many as 120 dead, or in any other accident. But the FAA and the jet's manufacturer, Boeing Commercial Airplane Group, said the directive was appropriate in wake of previous problems with the part.
The move, which came four days after Boeing voluntarily alerted its 747 operators to inspect the part, raises an issue long touted by the agency's critics: Does the FAA react fast enough to potential safety problems involving parts or maintenance?
The FAA has three times previously issued airworthiness directives calling for inspection of the fuse pin in 1979, 1986, and 1991. Most recently, investigators have been looking at the part in connection with last December's China Airlines crash near Taipei.
"The main question is whether there has been a sufficient sense of urgency attached to the AD [airworthiness directive]," said David H. Holladay, a San Diego-based aviation safety consultant. "If the engine separated because of the fuse pins, Boeing is in for some real problems and the FAA will have been in bed with them."
Yesterday's order affects 551 airplanes worldwide, including 143 registered to domestic carriers. It calls for ultrasonic inspection of the fuse pins within 30 days for older models. On models built since a redesign of the part in the 1980s, it applies only to 747 airplanes with Pratt and Whitney or Rolls Royce engines.
On those newer aircraft, the timetable is slightly more generous. The fuse pins connecting inboard engines, which have tended to be the site of problems, must be inspected within 30 days or prior to 5,000 total landings, whichever occurs later. Outboard engines are within 60 days or 5,000 landings.
The directive also calls for continuing periodic inspections of the pins, as frequently as every 500 landings in some cases.
The FAA and Boeing have been discussing what to do about the fuse pins since last spring because of the China Air accident, and met with carriers to discuss the issue as recently as mid-September. Boeing has received 15 reports of cracked fuse pins during the past seven years.
"We have no evidence linking this part to any accident and I think we've acted appropriately under the circumstances," said Christopher Villiers, a Boeing spokesman. "In all the cases we've found the pins were replaced without incident."
On Monday, Boeing issued a "service bulletin" to its 747 operators asking them to conduct fuse-pin inspections. The bulletin recommended airlines take a look at the part within 90 days.
That, according to industry experts, is the standard first response to any potential problem with a part.
Unlike the bulletin, the airworthiness directive is mandatory for U.S. carriers, and most foreign countries follow suit with equivalent directives to their airlines. Hundreds of directives are issued each year by the FAA and they usually follow manufacturer service bulletins.
The agency also has the power to ground an aircraft model by withdrawing its certification. Rarely exercised, that authority was last used by the FAA in 1979 when it grounded DC-10s following a crash at Chicago's O'Hare International Airport.
John Galipault, head of the Aviation Safety Institute in Worthington, Ohio said the FAA's actions demonstrate that it usually takes an accident to get regulators and the industry sufficiently motivated to issue a safety alert.
Corrosion around fuse pins has already been spotted by some of the major carriers.
Joseph P. Hopkins, spokesman for Chicago-based United Air Lines, said yesterday that United maintenance crews have already replaced some corroded pins on its 747s affected by the FAA order but found no evidence of cracking.
United is the only domestic carrier in the Baltimore-Washington area using 747s, flying out of Dulles International Airport. Baltimore-Washington International Airport has only one airline which has a regularly-scheduled 747 flight, KLM Royal Dutch Airlines.
No 747s serve National Airport. Dulles has five other foreign-based international carriers which regularly use 747s.