U.S. Recommended Checks of 737 Jet Engines

The explosion of an engine Thursday on a British Airtours Boeing 737 jetliner was the seventh of its kind in two years, and it occurred only a month after U.S. air safety authorities had recommended that these engines be closely inspected or reassembled.

The National Transportation Safety Board, which monitors accidents worldwide involving American-made aircraft, recommended July 22 that the Federal Aviation Administration establish an appropriate inspection program for all such engines that had not been repaired in the last 18 months.

An FAA official, however, said that the agency is seeking more data before mandating that such an action be taken on the engines, manufactured by Pratt & Whitney.

FAA spokesman Fred Farrar also said that agency officials were informed late Thursday by Pratt & Whitney engineers that the British accident involved a different engine part from the one that apparently had caused earlier failures.

Farrar said company officials believe a canister--a cylindrical chamber where engine combustion occurs--blew off the engine and struck the wing, causing a fire that killed 54 people aboard the British craft.

Pratt & Whitney JT8D-15 and -17 engines have failed during the takeoffs or initial ascents of Boeing 737s and 727s, and the Transportation Safety Board said in its recent recommendation that “the potential for more failures is high . . . with the attendant possibility of serious consequences.”

Turbine Disk Failure

An analysis of the seven engine failures worldwide shows that a part known as a second-stage low-pressure turbine disk has most often malfunctioned, the board said. It said that this type of failure had occurred in the aborted takeoff of a United Airlines 727 jetliner in Chicago in June, 1983, and in more recent accidents involving airlines of Canada, Syria, Algeria and Saudi Arabia.

Last September the FAA--acting on recommendations of Pratt & Whitney--ordered U.S. airlines to begin inspecting all JT8D engines for frictional wear and to modify them with tighter air seals, if such wear is evident. However, the safety board last month recommended stepped-up inspections on grounds that these engine failures were continuing to occur overseas, although Pratt & Whitney sent warning notices to all airlines last year.

Authorities said the jetliner that exploded Thursday had been delivered new from Seattle-based Boeing Co. in April, 1981. A company investigation team has been in contact with Boeing’s technical representatives in Britain and probably will visit the disaster site, Boeing spokesman Tom Cole said.

Farrar said the FAA has asked Pratt & Whitney engineers for a thorough briefing within two weeks after they have finished studying the latest accident.

Oil Pressure Loss

“For the time being,” he said, “we believe our existing inspection and repair requirements are sufficient.”

Overall, there have been 14 instances of engine trouble over the last two years on Boeing 737s in the U.S. commercial air fleet, according to reports on file with the FAA. These instances include engine stalls, excessive vibrations and losses of oil pressure.

Such reports are made by air carriers, maintenance stations, aircraft manufacturers and FAA inspectors. But because federal law is vague on the standards governing such reports, the total number of problems is believed to be much higher.

Times staff writer Richard E. Meyer in Los Angeles contributed to this story.