SDR reports still useful — Uplink Archive

The Seattle Times analyzed two decades of FAA service difficulty reports to document a pattern of rudder malfunctions in Boeing 737s, finding connections to unsolved crashes and prompting regulatory action. The investigation revealed that rudder problems may have contributed to multiple incidents, including the USAir crash near Pittsburgh and a 1991 Colorado Springs disaster.

The Federal Aviation Administration's database of service difficulty reports, despite the gaps found by the Cleveland Plain Dealer, is still good for spotting safety problems. The Seattle Times drove that point home in a front-page story documenting a raft of rudder problems in Boeing 737s.

The newspaper rummaged through two decades' worth of service difficulty reports, and found a pattern of malfunctions linked to the jet's rudder. In two dozen cases, pilots were forced to make unscheduled landings, emergency descents or return to the terminal gate.

Concerns ran deep that the rudder could sometimes reverse itself. The FAA ordered airlines in March 1994 to replace the rudder system's central hydraulic mechanism within five years.

The newspaper reminded readers that investigators considered rudder problems a possible cause of the USAir crash near Pittsburgh, but had yet to draw a conclusion.

Reporter Byron Acohido checked with USAir, which reported the jet that crashed did not have the improved rudder system. And the newspaper pulled an unsolved crash out of the National Transportation Safety Board's files - a 1991 disaster outside Colorado Springs; the last jetliner to stump NTSB investigators. It, too, was a 737. Investigators had focused on two theories, including a malfunctioning rudder.

In fact, Acohido said, as soon as he learned of the Pittsburgh crash, he suspected rudder problems may have played a role because of what he learned from the Colorado Springs disaster. "I had kept a file on the rudder problem since Colorado Springs," he said.

A private company supplied its catalog of FAA data to the Seattle Times. The firm provided 737 in dBase to the Seattle Times. Editorial systems editor Bob Higgins helped Acohido examine the data using Paradox.

The story included a chart depicting the rudder hydraulic system. And it highlighted, in a sidebar, 11 cases where flights went wrong because of rudder problems. Later, during hearings, Boeing officials said they knew of even more 737 flights disrupted by rudder problems than what was listed in the FAA database.