Four 737-400 Combis Experienced Similar Issues

Federal regulators have decided not to require any changes to Boeing 737-400s to address flap extension problems which occurred on four Alaska Airlines flights in January... but investigators still aren't sure what caused those issues.

As ANN reported, all four cases involved 737-400 "Combis," planes which have special equipment to allow them to convert back and forth between passenger and cargo duty. A similar -200 Combi is shown at right.

In each case, the flaps could not be fully extended during landings -- lengthening runway requirements, and triggering emergency declarations by the pilots.

The Seattle Post-Intelligencer quotes two FAA spokespeople as saying Alaska Airlines operation and maintenance complies with applicable regulations. A temporary fix for the problem was made by simply removing the doors which cover the flaps.

"The review involves looking at a host of factors (including the functioning of wing-flap doors) that can impact wing-flap performance," added Alaska Airlines spokeswoman Amanda Bielawski, adding the airline has "not yet come to any conclusions" on the exact cause of the issue.

In allowing Alaska to continue operating the planes without a permanent solution, the FAA also acknowledges it has not found a definitive cause for the problems last month.

"I want to re-emphasize that flaps are not necessary to safely land an airplane," agency spokesman Allen Kenitzer told the P-I. "But," he added, "when the flaps don't deploy and are expected, this is not handled as routine."

Boeing says it is supporting Alaska Airlines' ongoing investigation.

"We continue to collaborate with Alaska Airlines by providing them technical assistance during their review of 737-400 wing flaps," said Boeing spokeswoman Liz Verdier.

FMI: www.faa.gov, www.boeing.com, www.alaskaairlines.com