Times Archive: NTSB: Rudder problem likely cause of USAir Flight 427 plane crash

EDITOR'S NOTE: This story is being reposted Sept. 8, 2022, to mark the 28th anniversary of the crash of USAir Flight 427.

Just after 7 p.m. Sept. 8, 1994, a USAir flight carrying 127 passengers and five crew members suddenly crashed into a Hopewell Township hillside as it was preparing to land at Pittsburgh International Airport.

Less than 30 seconds went by from the first indication of a problem until the Boeing 737 crashed.

Hundreds of frantic callers flooded the Beaver County 911 center and attempted to describe where the plane had crashed. First responders arrived to find a catastrophic scene with no survivors.

It took investigators nearly five years to determine what likely caused USAir Flight 427 to crash into that hillside.

The National Transportation Safety Board issued a final report on March 24, 1999, concluding that the probable cause of the accident was a rudder issue that resulted in the flight crew losing control of the airplane.

The rudder, which protrudes from the aircraft's tail, is used to make the plane rotate on its vertical axis.

“The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit,” the report said. As a result, the plane rolled on its vertical axis.

That conclusion was reached after investigators from around the world -- including representatives from the United Kingdom, France, Denmark, Australia and Canada -- examined what transpired that day.

Many theories were investigated, according to the NTSB report.

The possibility of an explosion was ruled out.

The pilots’ toxicology reports showed no sign of drug abuse or abuse of over-the-counter medications.

There had been no reported difficulties with navigational aids or communications prior to the crash.

The likelihood of a bird strike was ruled out after debris collected from the plane was analyzed by an ornithologist at the Smithsonian Institution’s Associate Division of Birds, who determined the pieces had no characteristics resembling a bird.

The Air Accidents Investigation Branch of Farnborough, England, participated in the accident reconstruction effort. That agency was called to assist because it was involved in reconstructing Pan American World Airways Flight 103, which exploded and crashed near Lockerbie, Scotland. That accident, the result of a terrorist bomb, occurred in December 1988.

The Air Accidents Investigation Branch considered the destruction and fire damage from the Flight 427 crash “extreme for that associated with civil aircraft accidents,” and said the damage “complicated efforts to identify components and reconstruct the airplane.”

That agency and explosion experts from the Federal Aviation Administration and FBI all found no evidence of any pre-impact explosion on the flight.

Ultimately, the NTSB ruled that when the main rudder control power unit jammed, it caused the plane to move in the opposite direction and the flight crew to lose control of the plane. Though the flight crew recognized there was a problem and took immediate action to attempt a recovery, they were unable to do so.

“The flight crew of USAir Flight 427 could not be expected to have assessed the flight control problem and then devised and executed the appropriate recovery procedure for a rudder reversal under the circumstances of the flight,” the report said.

Training and piloting techniques were developed as a result of the Flight 427 crash that show it is possible to counteract what the NTSB called an “uncommanded deflection of the rudder in most regions of the flight envelope.” Such training was not available at that time for the Flight 427 crew.

Rudder system design changes also were made to new Boeing 737s, and existing planes were retrofitted to prevent a similar malfunction from occurring.

This article originally appeared on Beaver County Times: NTSB: Rudder problem likely cause of plane crash