Study of 737s Yields No Design Flaws

An extensive study of the Boeing 737 jetliner has turned up no design flaws in the world’s most widely used airliner that could have caused either of the crashes that prompted the review, the Federal Aviation Administration said Wednesday.

The FAA study was launched after USAir’s Flight 427--a Boeing 737-300--rolled suddenly to the left and plunged 5,000 feet to the ground near Pittsburgh, Pa., last Sept. 8, killing all 132 persons on board. Four and a half years earlier, United Airlines Flight 585--another Boeing 737--crashed in much the same way near Colorado Springs, Colo., killing 25.

The National Transportation Safety Board has never determined the cause of either crash. However, most aviation experts agree that the only control system on the planes that could have caused them to roll and dive as they did is the rudder--the hinged back half of the vertical part of the tail that is used to correct for crosswinds and to keep the jetliners from fishtailing.

Boeing records include at least 187 instances in which a 737 rudder system has malfunctioned, often causing the rudder to move on its own, but no rudder system glitch has ever been blamed conclusively for the crash of a 737.

The FAA said it will offer 27 safety recommendations for the jet.