Bursting Pressure Barrier Suspected in Japan Crash

Transportation Ministry experts examining the wreckage of the crashed Japan Air Lines jumbo jet said Friday that a rear bulkhead designed to keep pressurized air within the passenger cabin has been found in shreds at the crash site, raising the possibility that the barrier burst in flight, sending pressure into the tail assembly and causing the tail fin to disintegrate.

All but four of the 524 people aboard Monday’s JAL Flight 123 died when the Boeing 747-SR slammed into a mountain in the Japanese Alps. The accident was the worst single-plane disaster in history.

Hiroshi Fujiwara, deputy chief of the ministry’s investigating team, told a news conference that the jumbo jet’s pressure bulkhead had been “peeled like an orange” and was split at the seams, in five or six pieces. The bulkhead, a dome-shaped, aluminum-alloy partition with umbrella-like ribs, separates the pressurized cabin from the unpressurized rear section of the fuselage.

A round frame that forms the mouth of the bulkhead was found intact, he said.

Fujiwara said the investigators are focusing their investigation on the bulkhead and on the connections between the fuselage and the tail fin, or vertical stabilizer. He said they will gather the remnants of these parts and try to reconstruct the entire rear of the plane for further study. At the moment, he said, they cannot tell whether the rear pressure bulkhead was torn apart during the flight or upon impact at the crash site.

But he said that if the wall had cracked or broken during the flight, air from the pressurized cabin would have rushed into the unpressurized rear section of the fuselage and into the tail fin, creating explosive force as the pressure inside suddenly exceeded the lower pressure outside those sections at the jet’s high altitude.

That kind of explosion, Fujiwara said, could have blown off the plane’s tail fin and rudder, as well as the auxiliary power unit inside the rear fuselage.

JAL’s chief pilot, Capt. Yoshio Iwao, told the Associated Press that such a chain of events could also have damaged the plane’s hydraulic systems, leaving the pilot with no way to control the aircraft except for power from the four engines.

Parts of the tail fin, the rudder, and the auxiliary power unit were ripped from the plane in flight and fell into Sagami Bay, more than 100 miles from the crash site, where they were found this week.

Investigators believe they came off just before the veteran JAL pilot, Capt. Masami Takahama, 49, told Tokyo air controllers that he could not control the plane. It strayed far off the course it should have followed on the Tokyo-to-Osaka flight and crashed into Mt. Osutaka, 70 miles northwest of Tokyo.

By early today, nearly two dozen fragments of the aircraft had been found in the bay. Several of them floated ashore.

Other parts of the tail fin were found at the crash site.

The Transportation Ministry official said investigators will examine the pressure bulkhead for signs of metal fatigue--a process by which tiny cracks, over a long period, develop into fissures that eventually break, he said. If no signs of metal fatigue are found, they would be forced to conclude that pressure burst the wall and will try to determine the cause for that.

Noting that the bulkhead was damaged seven years ago, when the aircraft scraped its rear fuselage bottom during a “nose-high” landing at Osaka airport, he said investigators will consider whether repairs made then by the Boeing Co. left behind any small cracks in the bulkhead.

Fujiwara also said investigators had located the rounded rear end of the fuselage and were surprised to discover that it was badly damaged. He said the tip of the rear fuselage is usually the least damaged of all parts of an aircraft in a crash.

Engine Positions Noted

Investigators also found three of the aircraft’s engines on opposite sides of where they should have been if the plane had crashed head-first or on its belly.

The No. 3 engine, located on the right wing next to the fuselage, was found left of the main impact area, while the No. 1 and the No. 2 engines, attached to the left wing of the aircraft, were discovered to the right of the main impact area.

These locations indicated that the airplane, which caromed off one mountain ridge as it descended, may have rolled over in mid-air and crashed upside down on the next mountain ridge, Transportation Ministry officials said. A swath cut through trees on the first ridge marked the plane’s path for the search party, which did not arrive on the scene until 14 hours after the crash.

The No. 4 engine, outboard on the right wing, still has not been found.

Yumi Ochiai, 26, an off-duty JAL assistant purser on board who survived the crash, offered new details about the crash Friday in a television interview.

Screams, Then Calm

When an explosion-like sound rocked the plane at 6:25 p.m. Monday and the plane began to sway and weave, some of the 509 passengers started screaming. “ ‘Help me!’ . . .’Mama!’ . . . and other cries of panic broke out,” she said.

But after the initial panic, most of the passengers calmed down and helped each other don life vests, Ochiai told a Japanese reporter who interviewed her at her hospital bedside.

“Everyone sat down, fastened their seat belts and obeyed instructions,” Ochiai said in a soft, tired voice which was recorded and broadcast on radio and TV.

She said a flight attendant announced that, “We are in contact with the control tower, so please relax,”

After passengers were instructed to put on their life vests, “there were many who couldn’t find their life vests and others who put them on while reading instructions in pamphlets. There were also people who helped people sitting next to them put on their life vests after they had put on their own,” she said.

As the plane began to plummet, all of the passengers assumed the crash position, grasping their ankles with their hands, heads lowered to their laps, she said.

Ochiai, who suffered pelvic and arm fractures, said her hips still hurt.

Sand Into Mouth

After the crash, “I thought I must be saved. But I couldn’t move and I didn’t know what to do. . . . When I opened my mouth, sand came in. It was all I could do to move my head in a direction so that sand would not come into my mouth. I was so thirsty . . . , “ Ochiai said.

Sixteen hours later, about 11 a.m. Tuesday, when a Self-Defense Force soldier found her, “He shouted, ‘You’ll be all right!’ ” she recalled. “But my body hurt so badly I didn’t know what was going to happen.”

Relatives of Keiko Kawakami, one of the other survivors, said the 12-year-old seventh-grader told them that she and her parents still had their seat belts on 13 minutes after takeoff when the emergency occurred. All four of the Kawakamis cried out in pain as the belts seemed to tighten when air pressure dropped in the cabin, she said.

Her father, Eiji, 41, and her mother, Kazuko, 39, helped her sister, Fukiko, 7, unbuckle her seat belt and struggled to unbuckle their own, she said.

Moments before the plane began its final dive, the parents succeeded in unbuckling their seat beats but were unable to help her with her seat belt, Keiko said.

The bodies of Keiko’s father, mother and sister were identified Thursday. So far, 389 bodies have been recovered but only 196 of the victims have been identified.