Andrew Mollet

Boeing continues to take issue with suggestions there might be any link between a test-flight incident on a British Airways 737 more than two years ago and two earlier unexplained 737 crashes in the US.

The two unexplained 737 crashes occurred in Colorado Springs, Colorado in 1991 and near Pittsburgh in 1994.

"The 1995 British Airways incident involved yaw-damper oscillations that caused a rudder input of no more than 4%," says a Boeing source.

"In the case of the Pittsburgh crash, the indications are that the rudder input shot up to 27%, although it would also appear that it did not stick there.

"As a result, we are convinced that there is no strong correlation between the two incidents - or with the Silk Air crash in Indonesia in December, for that matter."

The UK's Air Accident Investigation Board (AAIB) recently issued a recommendation urging the FAA to mandate design modifications to ensure that electrical equipment beneath lavatories, doors and galleys is protected from leaking liquid.

The AAIB believes that the yaw damper oscillations experienced in the BA 737 was caused by liquid seeping into the aircraft's electrical and equipment bay.

Boeing has formed a team made up of the FAA, AAIB, airlines and other interested parties to review the issue.

The team has come up with a number of recommendations that Boeing plans to turn into a Service Bulletin to be released in mid-1998.

Source: Flight Daily News