Cockpit door problems quietly fixed

SEATTLE — The Northwest Airlines maintenance mechanic standing inside the Airbus A330 pressed the microphone button on his handheld radio and heard a very unexpected noise: the sound of the airplane’s newly secured high-tech cockpit door operating.

A glitch in the door’s security technology had allowed radio interference from the walkie-talkie to scramble the electronics inside the door’s locking mechanism.

The incident, in Minneapolis in December 2003, prompted to a yearslong, secretive engineering effort to fix a glitch in some cockpit doors that were fortified following the Sept. 11, 2001, terrorist attacks, The Seattle Times reported in Thursday editions.

The glitch affected about 400 A330s and A340s made by Airbus SAS. About six months later, Chicago-based Boeing Co. learned from airline customers that it had the same problem with about 1,700 jets, the newspaper said.

Boeing said it had fixed all its jets by last month. Airbus spokeswoman Mary Anne Greczyn told The Times last week that the fix is “nearly completed” on all of that company’s affected jets worldwide.

Officials from both airplane makers say there was no immediate danger to the flying public. The mechanic who inadvertently triggered the lock needed to be standing in one precise spot, and the walkie-talkie needed to be tuned to a specific frequency with a certain signal strength for the glitch to occur.

“It’s an extraordinarily limited issue,” Greczyn said.

Four months after the Sept. 11 attacks, the FAA began requiring that cockpit doors be strengthened on all jets flying in the United States. The mandate was especially difficult because the doors had to be strong enough to withstand bullets yet also capable of bursting open if there was a sudden loss of cabin pressure.

Also, airlines had just 15 months to upgrade thousands of airplanes.

Boeing and Airbus both used a Fullerton, Calif., supplier, Adams Rite Aerospace, for their door-locking mechanisms. Both aircraft makers said the supplier passed early certification tests and interference requirements. Executives with Adams Rite did not return The Times’ calls for comment. The company also declined to comment to The Associated Press.

Both plane makers used doors that are secured with aluminum rods activated by an electronic signal. Rapid decompression would also unlock the door.

Following discovery of the glitch, Boeing said it has provided a manual bolt that could be used as a backup. Airbus said a mechanical backup has been designed for its planes as well, available to customers to use at their discretion.