FAA Order Curbs Use of Older 737s : Altitude Is Limited; Inspection to Focus on Defects in Metal

Federal officials issued an emergency order Saturday restricting the use of older Boeing 737 jetliners until they can undergo detailed inspections, as investigators here focused on metal fatigue as a possible cause of the accident in which an Aloha Airlines plane was ripped open in flight Thursday.

Under the order, issued in Washington by FAA Administrator T. Allan McArtor, no Boeing 737-100 or 737-200 that has been through more than 55,000 landings may fly at altitudes greater than 23,000 feet until the inspections are completed.

In the case of the damaged airliner, “the focus of the investigation is on the structure itself; (on) what, if any, causes there might have been to create hull fractures,” National Transportation Safety Board member Joseph T. Nall told reporters at Kahului Airport. “Obviously, we’re interested in metal fatigue.”

‘Go Team’ on Scene

Nall arrived on Maui on Friday to head an 11-member “go team” of NTSB inspectors. His remarks Friday evening were unusual, because federal investigation team members seldom comment about the possible causes of an accident so soon after it has occurred.

The 19-year-old Boeing 737-200 was flying at 24,000 feet Thursday afternoon when a 20-foot section of the upper fuselage suddenly peeled back and ripped off. Despite the damage, pilot Robert Schornstheimer, managed to land the plane after 13 harrowing minutes in the air, but a flight attendant is missing--presumed hurled into the sea by the explosive decompression--and 61 of those aboard were injured.

Officials at Maui Memorial Hospital said seven remained hospitalized Saturday--three in serious condition and four “satisfactory.”

Search for Defects

The inspections ordered by the Federal Aviation Administration are designed to search for cracks, corrosion or other defects in the aluminum skin of older planes at the roof of the fuselage--defects that might lead to the sort of catastrophic blow-out which tore away the top of Aloha Airlines Flight 243.

Nall said that the plane--the 152nd of more than 2,000 737s built by Boeing--is a “high-cycle” aircraft, having been pressurized between 85,000 and 90,000 times, once during each of its flights for Aloha.

The FAA order will require American Airlines to inspect 16 planes used on short flights serving Los Angeles, Orange County, San Diego, Oakland, San Francisco, Sacramento, San Jose, Reno, Lake Tahoe, Seattle and Portland, Ore, airline spokesman Edward Martell said. The planes were acquired when American absorbed AirCal in July, 1987.

American planned to begin inspecting the planes Saturday night and hopes to complete the process by Friday, Martell said. In the meantime, the airline will continue to fly the planes and expects “virtually no shuffling of flights because on these short hauls we seldom get over 23,000 (feet),” he said.

Piedmont Airlines has 17 planes affected by the order that it uses on short hauls between Eastern cities, according to Piedmont spokesman William J. Kress.

Aloha had four old-model 737s, including the one involved in Thursday’s incident. The airline grounded the other three planes Friday.

No other domestic airlines have planes affected by the order, FAA spokesman Fred Farrar said. Boeing spokesmen, however, estimated that at least 29 planes owned by foreign carriers have undergone more than 55,000 landings but declined for the present to release the names of the foreign airlines involved. The FAA has informed foreign air safety regulators of its order, but foreign carriers are not bound by it.

Order Based on Estimates

The details of the FAA’s order are tied to estimates of how fast metal fatigues and how the fatigued metal can fail under pressure.

“Each landing represents a pressurization cycle,” Farrar said. “The airplane is pressurized and swells slightly, then depressurized and shrinks. Over time, that’s where metal fatigue comes from.”

Once the metal becomes fatigued, the difference in pressure between the cabin and the outside atmosphere at altitudes above 24,000 feet--five pounds per square inch--could be enough to blow a hole through the skin of the plane, he explained.

The FAA said the ceiling altitude of 23,000 feet was selected until the inspections are made because the pressure differences between the inside and outside of aircrafts do not begin to put a significant strain on a hull until the plane reaches about 24,000 feet.

The inspections will take about 60 man-hours of work for each plane, a spokesman for Boeing said, and FAA officials agreed that McArtor’s order, called an airworthiness directive, will require an intensive look.

“You can’t just do it from the ground,” said Dick Meyer, a spokesman at the FAA’s regional office in Seattle, which supervises the safety of commercial aircraft. “It requires the trained eyes of maintenance people who can look to the degree that they’re checking the rivets.”

Cites Directive Last Fall

Nall noted that Boeing issued an airworthiness directive last fall for high-cycle 737s that called for inspections of the aircraft, addressing the question of fatigue along the top of the planes.

“We are in full compliance with the directive,” said Stephanie Ackerman, an Aloha Airlines spokeswoman, who added that the inspections turned up nothing unusual.

The current order strengthens the earlier directive by ordering that the inspections take place immediately and by limiting flight altitudes until the inspections are finished.

The planes to be inspected are all at least 17 years old, Boeing spokesman Craig Martin estimated. The company first built the 737-100 in 1967 and a few years later introduced the Model 200. The 110-seat plane, which can carry a full load nearly 2,000 miles at speeds of more than 550 m.p.h., has proved a favorite of airlines as an economical vehicle for short routes, and most of the roughly 1,500 planes sold are still in service. There is a thriving market for used 737s, said Boeing spokesman Tom Cole, and they sell for anywhere from $3 million to $10 million.

The 11 members of the NTSB investigative “go team,” put in their first full day of on-site work here Saturday.

Several team members began the painstaking task of inspecting the fuselage of the plane, which has remained parked on the taxiway, where it came to a halt after the emergency landing at Kahului Airport.

Checking Records

Others began checking maintenance and crew records and interviewing witnesses--both passengers and crew members from Flight 243 and people who saw the crippled plane land.

The cockpit voice recorder and flight data recorder from the plane have been flown to Washington for inspection. These “black boxes” record the cockpit conversations and provide a readout of the plane’s attitude, altitude and headings during a flight.

The NTSB team is being assisted by local fire and police personnel and by Aloha, the FAA, the Air Line Pilots Assn., the International Assn. of Machinists and the Assn. of Flight Attendants--all of whom sent investigative experts here to assist in the investigation.

Nall said the on-site inspection is expected to take about a week, but that final conclusions are not expected for months.

Surviving crew members remained in seclusion Saturday, and Aloha Airlines said no interviews would be granted “until the investigation is complete.”

“It could take six months, it could take nine months--you never know,” said Aloha spokeswoman Ackerman.

She said that the crew’s silence was in keeping with company policy and at their own request.

Another Aloha employee, who asked not to be identified, said the heroic crew did not “completely understand” the nature of the emergency when they landed the plane.

That ignorance was undoubtedly a blessing, the employee added. “It can’t help your confidence to go back and see a third of your cabin gone,” he said.

Eric Malnic reported from Kahului and David Lauter from Washington. Staff writer Tamara Jones in Kahului also contributed to this report.