A huge section of the roof of an Aloha Airlines jet, which safely made an emergency landing on a Hawaiian island Thursday, tore loose and peeled off over the Pacific after an apparent structural failure weakened its fuselage, accident investigators said yesterday.

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A flight attendant, Clarabelle Lansing of Honolulu, was sucked through the opening, and 61 of the 94 others aboard were injured -- one critically -- as the pilots maneuvered the plane down from 24,000 feet and landed with an engine on fire at Kahului Airport on Maui Thursday afternoon.

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"There was a big bang when it happened and everybody looked up and we were looking at blue sky," said Bill Fink, a passenger who was flying home to Honolulu from Hilo.

 

The twin-engine, 110-seat Boeing 737-200 jet was halfway into a 40-minute flight when it suddenly lost cabin pressure and a 20-foot by 11-foot chunk of the fuselage, exposing passengers in the 96-foot cabin to open sky.

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The pilots transmitted a "Mayday" call to air traffic controllers when the plane was about 25 miles southeast of Maui. Despite the loss of pressure, the captain, Robert Schornstheimer, 42, a 12-year employee of the airline, and copilot, Mimi Tomkins, were able to bring the disabled jet in for a smooth landing.

 

Investigators from the National Transportation Safety Board yesterday examined the jet, which one described as looking similar to a convertible with wings, and searched for tiny cracks and tears in the aluminum skin.

 

Investigators are pursuing a theory that a possible tear or crack could have caused an initial loss of cabin pressure and that the force of the winds at 24,000 feet tore away the top of the fuselage over the first-class section.

 

Using records and logbooks, investigators began the painstaking reconstruction of the jet's history in an attempt to trace any previous problems with pressurization, the metal fatigue that could cause cracking or improperly repaired rivet holes.

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Last October, the Federal Aviation Administration ordered airlines to inspect older-model 737s for cracking near an area of the upper fuselage where sections of sheet metal overlap. The order was issued in response to a bulletin three months earlier from The Boeing Co. On April 14, Boeing reissued the same bulletin as a reminder to airlines to inspect for cracks.

 

The FAA directive said routine inspections in three other 737s turned up cracks near fasteners that join sheet metal panels, according to FAA documents.

 

"If the cracks suddenly joined together . . . extensive structural damage and rapid depressurization of the airplane could result," the order warned.

 

Boeing's recommendation applies to 291 of the fleet's oldest planes, or planes which have made more than 30,000 landings. The safety board has not yet determined whether the jet involved in Thursday's incident was inspected, but Aloha spokeswoman Stephanie Ackerman said the airline is "in full compliance with the October directive." She said the inspections were conducted as outlined by the FAA and that nothing unusual was found.

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The jet, which was No. 152 off the Boeing assembly line, has made the second largest number of landings than any other plane in the 737 fleet, according to a Boeing spokesman. Aloha also flies the 737 that has made the most landings. Boeing has built 1,109 of the 737-200 models, Boeing spokesman Tom Cole said.

 

Aircraft age is measured by the number of hours flown and its susceptibilty to metal fatigue is measured by the number of takeoffs, pressurizations and landings. The Aloha jet has flown 35,310 hours and made 89,193 landings, according to investigators.

 

Over the last five years, Aloha filed 22 reports that are required if major components on a plane malfunction or are discovered to be amiss during maintenance inspections. Twenty-two reports is not considered unusual for a 19-year-old plane, and they include problems with a hydraulic pump, a nose landing-gear door latch, a tire and an engine oil filter.

 

Eleven of the reports dealt with cracks, and three involved corrosion, although none was in the area of the fuselage that broke away Thursday, an FAA spokesman said.

 

The jet was sold to GATX Leasing Co. in April 1969, which leased it to Aloha the same month. The airline, based in Honolulu, primarily flies short-hop flights around the Hawaiian Islands. Aloha Airlines owns ten 737s and leases two others, and announced plans earlier this year to acquire two additional jets and hire an additional 100 employees, enlarging its staff to 800.

 

The airline's growth was attributed, in part, to the collapse earlier this year of a competitor, Mid Pacific Airlines.

 

FBI investigators, who were called in to search for a bomb, bowed out of the investigation after finding no evidence of an explosive device, an FAA spokesman said.

 

DISASTER ON FLIGHT 243

 

BOEING 737-200

 

Type: Twin-turbofan short-range transport

Power Plant: Two Pratt & Whitney JT8D turbofan engines in underwing pods

Wing Span: 93 feet

Length Overall: 100 feet, two inches

Height Overall: 37 feet

 

Background: Boeing announced the decision to build this short-range transport in 1965 and deliveries began in 1967. Deliveries of all versions of the 737 totaled 1,490 as of March 31, 1988; 975 were in the 200 series.

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1-Aloha Airlines Flight 243, a Boeing 737-200 with 95 people on board, was flying from Hilo to Honolulu at 24,000 feet Thursday when the forward cabin was ripped apart.

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2-One flight attendant was apparently lost through the opening of the plane and 61 passengers were injured, two of them critically.

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3-The aircraft flew on for about 25 miles, then landed at Kahului Airport on Maui with one engine on fire.