Needs Work

Are commercial airliners being maintained properly? A barrage of questions about passenger-jet safety were raised last week in the midst of the busy summer travel season. The Air Transport Association, an industry trade group, reported that U.S. carriers are facing a serious shortage of mechanics even as demand for them is growing. Meanwhile, as if to point up the understaffing in the hangars, several airlines were forced to abort flights because of mechanical problems:

-- The most frightening accident of the week was reminiscent of the July 19 crash of a United Airlines DC-10 in Sioux City, Iowa, caused when the rear engine exploded, cutting the plane's hydraulic flight controls. On Wednesday the rear engine shattered on a Northwest DC-10 headed for Minneapolis, blasting holes in the engine housing. The plane landed safely in Denver. In the first mishap, the engine was a General Electric model, in the second, a Pratt & Whitney; no cause has been determined for either explosion.

-- Another Northwest DC-10 turned back to Detroit immediately after takeoff because the flap controls were not working properly. By week's end many anxious travelers were avoiding bookings on DC-10s. Addressing the fears, Federal Aviation Administrator James Busey maintained that there is no evidence that DC-10s are less safe than other airliners.

-- Other jets came in for their share of problems. A Trump Shuttle 727 skidded to a stop in a shower of sparks at Boston's Logan Airport after its nose gear failed to drop for landing. An American Airlines 767 flying from Phoenix to Chicago landed in Albuquerque after a valve burst in its hydraulic system.

No one was injured in last week's incidents, but the mechanical glitches renewed concern about whether maintenance crews that are stretched thin can maintain an adequate margin of safety. Not only do federal rules require modifications on thousands of older jets but the airlines are expanding their fleets with new, technically complicated planes. The ATA report, based on a survey of 21 major airlines, found that carriers have been unable to find mechanics for 4,000 vacancies out of a total of 69,000 positions. More troubling, the number of applicants for mechanic's positions is declining.