Jet’s Reliability Problems Eased as Aircraft Aged
The 1971 Boeing 747 being flown as TWA Flight 800 Wednesday night had fewer reported reliability problems as it aged, according to maintenance records kept in a Federal Aviation Administration database examined by The Times.
Since 1974, the aircraft suffered 11 in-flight engine failures or shutdowns and made 20 unscheduled landings because of mechanical or engine problems, according to the FAA’s list of 108 service difficulty reports. But the last reported unscheduled landing was in March 1988. An engine was shut down but flight continued in August 1995. Before that, the last reported engine shutdown in flight was in January 1988.
None of the 108 problems reported appeared to threaten the overall integrity of the plane or the safety of the passengers. Certainly the reports contain no hint of conditions that could lead to the catastrophic in-flight explosion and breakup that destroyed the aircraft Wednesday night.
However, the plane had flown a lot of hours compared to most other 747s in use by U.S. airlines.
Only five other 747s had accumulated more than the 87,000-plus hours and 16,000-plus takeoff and landing cycles recorded for the 747 that exploded in midair off Long Island, N.Y. And four of those senior citizens were also flown by TWA. The fifth belonged to Tower Air Inc.
The Boeing Co. gave the TWA 747 serial number 20083 when it was built. The FAA registered it with tail number N93119 and TWA give it a fleet number of 17119.
The maintenance histories of airplanes and many of their individual parts are detailed in service difficulty reports filed by aircraft mechanics and stored in a database by the FAA. The information can highlight recurring problems in a particular model or in a particular part used in various models. But no such problems were highlighted in the 42 service difficulty reports filed on N93119 between December 1988 and August 1995.
More than half of the reports made since 1990 documented repairs made during two separate airframe overhauls in 1990 and 1992. They concerned a variety of small cracks, a couple of small broken frame members and some minor corrosion. One of the cracks, an inch long, was in a fuel tank.
Engine problems were reported only twice in the eight-year maintenance history recounted in the FAA database.
The last report on N93119 was in August 1995 when engine 1 was shut down in flight because of a low oil level. A leaking oil line was replaced.
No other major U.S. airline flies a fleet of Boeing 747s with as many hours on them as those of TWA, according to the FAA database.
The Times examination of the service difficulty report database found maintenance records for 18 TWA 747s. One had nearly 100,000 hours and nearly 18,000 takeoff and landing cycles at its last database entry in February 1995.
Three others had more than 90,000 hours of operation; five had more than 80,000 hours, and seven had more than 70,000 hours. The freshest plane in the fleet had more than 56,000 hours.
In February, TWA placed a $1-billion order with Boeing for 20 new jetliners.
No other airlines had filed maintenance reports on planes with 90,000 or more hours, and only four other 747s with 80,000-plus hours were reported by currently scheduled U.S. airlines. United Airlines and Continental Airlines were flying one each and Tower Air had two. Evergreen International Airlines Inc., a freight carrier, also had a 747 with 80,000-plus hours flying.
Pan American World Airways, which stopped flying in 1991, also had an old fleet, with nine 747s showing between 80,000 and 90,000 hours when it stopped flying.
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The Boeing 747
The original 747-100 (16 built) was introduced into commercial service in January 1970. Since then, the jumbo jet has established itself as one of the airline industry’s most popular aircraft, but it has also become a frequent target of saboteurs because of its size and easy identification. Here are some facts about the aircraft:
Dimensions
Type: Four-turbofan heavy commercial transport
Cockpit crew: 3
Seating: 452 passengers
Length: 231 ft. 10 in.
Height: 63 ft. 5 in.
Maximum speed: 607 mph
Manufacturer: Boeing Co., Seattle
Aircraft in service: 1,082 including the current 747-400 model
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Accident Record
Accidents resulting in “loss of aircraft hull,” in rate per million departures
Boeing 747: 1.64
All large commercial jets: 1.83
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Disasters involving the 747
* Lockerbie, Scotland 1988: Bomb explodes aboard Pan Am Flight 103, killing 270 people.
* Ireland, 1985: Bomb suspected in crash of Air India jet off Irish coast, killing 329 people.
* Libya, 1973: Terrorists blow up an empty Japan Air Lines jet on the tarmac of an airport.
* Tenerife, Canary Islands 1977: Collision of two jumbos kills 583.
* Amsterdam, 1992: El Al cargo jet crashes into an apartment building, killing 50. Crash is blamed on design flaw, prompting modification in fleet engine mounts.
Sources: Jane’s “All the World’s Aircraft”; Associated Press; Reuters; Times staff and wire reports.
Researched by VICKY McCARGAR / Los Angeles Times
