The fire that killed 54 people on British Airtours Flight KT328 yesterday came during what is already the worst year in civil aviation history and refocused attention on two of aviation's oldest safety problems: engines sometimes fail and airplanes burn, especially when fully fueled.

Early reports from the scene indicate that a failure -- possibly in the engine's combustion section -- resulted in ruptured fuel tanks and lines that fed an enormous fire that spread quickly. The pilot aborted his takeoff and braked the plane on the runway at Manchester, England, but as has happened depressingly often, fire and toxic fumes claimed many victims in an otherwise survivable airplane accident.

The International Civil Aviation Organization in Montreal said yesterday that 1985 is already the worst year for civil aviation, with an estimated 1,400 deaths in 15 accidents worldwide. Coincidentally, it immediately follows the best year, 1984, when there were 224 deaths in the same number of accidents.

The higher toll this year is attributable in part to two crashes involving loaded Boeing 747 jumbo jets: the Air India crash off the Irish coast June 23 that killed 329, and the Japan Air Lines crash Aug. 12 that killed 520. The causes of both accidents are still unknown, although a bomb is suspected in the Air India crash.

The immediate suspect at Manchester is the left underwing engine on the two-engine Boeing 737-200 aircraft. Like all jet engines, it has a compressor section, where air is compressed and sent to a combustion chamber, then a turbine section, where exhaust gases turn the turbine, which also turns the compressor.

It was first thought yesterday that an engine part -- possibly a fan blade or a disk in the compressor or turbine sections -- flew apart and severed fuel lines. Aviation sources said later, however, that there did not appear to be a failure in the engine's moving parts, but rather in one or all of several combustion chambers that ring the center of the engine.

That scenario raises questions about why check valves would not have cut off fuel to the engine after the fire started and the crew attempted fire-suppression techniques.

The sources said preliminary information indicated yesterday that the engine problem appears unrelated to several recent similar-sounding events involving the same type of engine, the most widely used commercial jet engine.

The power plant on the Boeing 737-200 is the JT8D, built by the Pratt & Whitney division of United Technologies Corp. In addition to the 737, it powers the other airplanes most frequently flown today, the Boeing 727 and the McDonnell Douglas DC9. Those three model types represent about two-thirds of the U.S. major airline fleet and power 95 percent of all standard-body jetliners in the world, according to Pratt & Whitney.

On May 11, the captain of a Saudi Arabian Airlines Boeing 737-200 aborted his takeoff from Doha Airport in Qatar after "a catastrophic and uncontained failure" of the right-wing engine started an engine fire, according to the National Transportation Safety Board. All 104 people on board safely evacuated the plane. Six other incidents worldwide occurred as aircraft were taking off or climbing out, when the engines spin as rapidly as 8,000 revolutions per minute. There were no fatalities in any of those incidents.

The safety board found that wear around one of the rotating parts, called a second-stage low-pressure turbine disk, had caused those problems. It recommended an FAA survey of engines with similar service life and repairs. The board did not classify its recommendations as urgent.

An FAA spokesman said yesterday that Pratt & Whitney is performing the survey, which is near completion. Further action will be discussed based on the survey results. The board also recommended that foreign users of the 737 be informed of the problem, and the FAA said yesterday that it is doing so. The Manchester accident comes as safety from fire in airline passenger cabins continues to be a big issue on Capitol Hill. The House Public Works and Transportation aviation subcommittee became so frustrated last year with what it perceived as FAA foot-dragging on improving cabin safety that it legislatively required FAA Administrator Donald D. Engen to send the committee a monthly letter on how each of several safety issues was progressing through the regulatory mill.

The big items are tougher flammability standards for materials used inside airline cabins and improved breathing equipment and fire-fighting training for flight attendants. The first proposal is still open for comment, but the FAA has promised to complete action by Dec. 1. The second proposal is undergoing analysis by the FAA's parent Transportation Department and the Office of Management and Budget. Other proposals have been completed or are under study.