Boeing, FAA at odds over jet rewiring timetable Firm says it needs 2 years, questions fuel area order

July 25, 1998|By SEATTLE TIMES

SEATTLE -- Boeing's resistance to proposed new wiring rules for 747 jumbo jets could unnecessarily delay changes aimed at preventing accidents similar to the in-flight explosion of TWA Flight 800, say Federal Aviation Administration regulators.

The aircraft maker has told the FAA it needs up to two years to develop a solution for a proposed safety order, which would keep high levels of electricity from entering volatile 747 fuel tanks.

Moreover, in its formal response to a proposed FAA airworthiness directive, Boeing questions the need for the modifications. They would shield and isolate low-voltage, fuel-measuring wires leading into 747 center wing tanks from high-voltage wires for other systems.

The dispute, detailed in letters and documents contained in an ++ FAA docket, is the kind of standoff between Boeing and safety regulators that seldom surfaces publicly.

It also offers a rare glimpse into a routine deliberative process -- safety rule-making -- and provides a snapshot of the fuel-safety issue that has absorbed regulators and the aviation industry for nearly two years.

Given the time needed to implement the wiring system changes involved, the time frame for fleet-wide compliance now could stretch to more than five years after the 1996 TWA crash, which killed all 230 aboard.

The task of rerouting up to 2,100 feet of wiring -- strung through remote areas behind panels, from the cockpit to an area just behind the wing -- will be complex in design and difficult for operators to perform, the company says.

In an internal document about the forthcoming rule-making decision, FAA engineers don't buy Boeing's design argument: "We believe that they can issue a service bulletin in less than 12 months if they choose to commit the appropriate resources," the FAA engineers say.

They claim Boeing has "designed entire new airplanes in less than 24 months."

It appears the agency is poised to issue an airworthiness directive that gives Boeing less than the 18 to 24 months it says it needs to prepare -- but more than the originally proposed one year.

Complying with the directive would take even longer -- as much as three years. That would include Boeing's design work, its distribution of necessary parts and time for 747 operators to install the new wiring during the major maintenance checks 747s undergo every year or two.

FAA officials and Boeing both declined to comment. It's not clear from federal documents when the safety order will be issued or how closely it will adhere to the FAA's draft version now circulating.

The debate, however, is clearly framed in the proposed safety order's docket, a folder at the FAA's Transport Airplane Directorate in Renton. The docket's contents include letters from industry groups, manufacturers and airlines.

By its very definition, an airworthiness directive addresses an unsafe condition, but Boeing claims the fuel-measuring system is safe as designed and delivered, given proper maintenance. Multiple failures would be necessary to enable a spark inside the tank large enough to cause an explosion.

A mandate to shield and separate wiring, Boeing wrote in its response, would "represent the addition of another layer of safety, and therefore immediate or accelerated incorporation is not required."

Not so, says the FAA in its internal document: "We need to be clear that these design changes are required to bring the 747 up to the fuel-system safety standards of other airplane models of the same vintage as the 747."

The multiple failures necessary are not far-fetched, the agency says.

The directive would require shielding and separation of wiring that leads to the fuel-measuring probes inside center wing tanks on 747-100s, -200s, -300s, -SRs and -SPs. The later 747-400 model has a different design.

The proposed order is only one of many implemented or under consideration since the crash of Flight 800, which has been blamed on a fuel tank explosion of internal origin.

Pub Date: 7/25/98

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.