The Federal Aviation Administration (FAA) on Monday sent a team of safety inspectors into Boeing's Renton and Everett assembly plants to conduct a special review of its manufacturing procedures.

The Federal Aviation Administration (FAA) on Monday sent a team of safety inspectors into Boeing’s Renton and Everett assembly plants to conduct a special review of its manufacturing procedures.

The move follows the discovery of metal shavings inside the fuel tank of a new Japan Airlines (JAL) 767 passenger jet during ground maintenance earlier this month.

The plane was delivered to JAL in early February and had flown 325 hours. The shavings are thought to be a result of the manufacturing process, likely debris from drilling rivets.

The FAA review, expected to last at least several days, will focus on Boeing’s procedures for preventing what the industry calls FOD, or Foreign Object Debris, meaning any material or object that isn’t supposed to be on the airplane when it leaves the factory.

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Boeing spokesman Marc Birtel said Tuesday the review will not disrupt airplane deliveries or the ongoing certification activities on the 787 and 747-8 programs.

However, coming on top of hints earlier this week that a recent 737 in-flight passenger cabin rupture may have been due to poor workmanship, the FAA action throws another embarrassing spotlight on Boeing’s internal safety oversight.

Birtel said a ground maintenance crew troubleshooting an imbalance in the fuel tanks of the 767-300 traced the issue to “small metal particles in the fuel tank.”

Boeing voluntarily disclosed the safety lapse to the FAA on April 21. The company immediately reviewed its manufacturing process and reiterated to employees the FOD-prevention procedures mandating that mechanics clean, wipe and vacuum after work is completed.

It also inspected fuel tanks under assembly and found no FOD or metal shavings.

A person familiar with the details of the JAL airplane incident said the airline noticed abnormal fuel transfers between the fuel tanks in the wings and the central fuselage. Maintenance technicians seeking the cause found a metal shaving in the left main wing fuel tank trapped in an outlet valve, preventing it from closing all the way.

Further inspections turned up more metal particles. While none were found in the filter that strains fuel going into the engines, there were some in a low spot of the wing tank used to drain fuel samples and more in the center tank inside the fuselage.

“That stuff is supposed to be vacuumed out and flushed,” the person said. “Even after they had flown it a while, there was still metal sloshing around at the bottom of the tank.”

Such particles could potentially damage an airplane.

“That’s a pretty unusual incident,” said Jim Hall, former chairman of the National Transportation Safety Board. “It goes to the quality issue of the production. … I’m pleased they self-reported it.”

He said he’s worried that the quality control that has been Boeing’s hallmark in the past could slip under the pressure to cut costs.

“One of the reasons that aviation is so safe is the high standards,” Hall said. “Boeing has stood for that high level of quality for a number of years.”

The agency instituted the broader safety review in Renton and Everett as an additional precaution to ensure that Boeing’s FOD prevention procedures are adequate.

Boeing’s Birtel said the company has had “a multitiered quality system aimed at eliminating FOD from our products for a number of years.”

The FAA review will look at the procedures in place, inspect the paperwork and talk to people on the line about how they do their jobs.

“We are going to work together with the FAA to ensure our FOD program complies with manufacturing standards,” Birtel said.

Dominic Gates: 206-464-2963 or