WASHINGTON (

TheStreet

) -- U.S. airlines have quietly removed oxygen devices from the bathrooms on 6,000 aircraft, responding to FAA concerns that an unobserved passenger could trigger a fire using such a device, industry sources say.

The Federal Aviation Administration issued an airworthiness directive on Feb. 10 ordering the removals, with the work to be completed within 21 days after each airline received the directive, the sources say. All work is expected to be completed within a few days. Airlines have been able to accomplish the work during routine maintenance.

Additionally, the agency alerted foreign aviation regulatory authorities, and some have ordered carriers in their countries to follow the same policy, sources say.

The danger was that "you could take the generator and

manipulate it to create a hazard," said aviation safety consultant John Goglia, a former member of the National Transportation Safety Board. "You could have an oxygen-fed fire that would be extremely hot."

In mid-2010, the FAA began to consider how to deal with the hazard posed by the bathroom oxygen generators, a source said. That consideration was not triggered by any specific security event.

"It was a vulnerability," Goglia said. "To the FAA's credit, they knew they had to do something, and they decided to take action."

TheStreet

learned of the removal effort from an airline source in mid-February, but agreed to delay publication of this story until the work was nearly completed. The FAA declined to comment.

Most carriers have chemical oxygen generators in the lavatories in case a depressurization event occurs in the cabin while the lavatory is in use. The same type of generator is also provided above each seat and can drop down in the event of an emergency. The difference is that a terrorist or disturbed passenger could conceivably tamper with a lavatory generator while unseen by other passengers.

The case of the 1996 crash of a

ValuJet

McDonnell Douglas

DC-9 near Miami resulted from a fire that was fueled by oxygen generators in the cargo hold. The event provides the best-known example of the danger connected with oxygen's high flammability. However, the differences are noteworthy; the ValuJet crash involved multiple oxygen generators and a fire that developed gradually in an area that was unobserved. Additionally, human beings were not involved in the ignition of the fire.

Lavatory oxygen generators provide a margin of safety for passengers who are caught in the facility when a depressurization event occurs. However, the events are extremely rare, and rapid depressurization events are even rarer. When such events occur, pilots are trained to descend as quickly as possible to a safe altitude.

In connection with the removals of the lavatory devices, the FAA is reinforcing its guidance to carriers mandating that flight attendants check the lavatories when a depressurization event occurs, sources say.

Spokespersons for

American

(AMR)

,

(AMR)

,

United

>

(LCC)

and US Airways >

(LCC)

said the carriers comply with all FAA directives, but declined to comment further.

Delta

>

(DAL) - Get Report

would not comment.

-- Written by Ted Reed in Charlotte, N.C.

>To contact the writer of this article, click here:

Ted Reed