Stronger Effort Needed to Assure Safety of Aircraft Electrical Systems

Air Safety Week, Oct 9, 2000

"When safety is at risk, we cannot afford to make the needed changes at a snail's pace."

Rep. Tillie Fowler (R-Fla.) Chair, Oversight, Investigations and Emergency Management Subcommittee

More action needs to be taken to assure the safety of the flying public from electrical system faults. At a Congressional subcommittee hearing last week, the second in a year it has devoted solely to aircraft wiring troubles, the specter of the TWA Flight 800 tragedy clearly loomed over the proceedings.

The legislators were concerned that the industry does not appear to have mobilized a major effort to assure the safety of aircraft electrical systems, and that new technologies like arc fault circuit interrupters as well as increased training of mechanics are too slow in coming. Given the potentially catastrophic consequences of electrical arcing, subcommittee chairperson Rep. Tillie Fowler declared that bad wiring "is an issue with no margin for error."

"The FAA must stop dragging its feet and start implementing alterations to older aircraft and their wiring systems," she groused.

With a brace of government and industry officials facing the committee prepared to testify, Rep. James Traficant (D, Ohio) applauded the National Transportation Safety Board's (NTSB) exhaustive investigation of the TWA 800 crash: "The NTSB focused on the reality of that great tragedy...(a) center wing tank explosion due to an electrical wiring harness problem."

Less wiring by design?

"Everyone knows that after years of wear and tear, the chafing takes away from the insulation and leads to that kind of disaster," he said. Traficant expressed doubt that the industry has procedures in place to catch wiring problems through inspection. Rather, he suggested that with more wire going into new models, it might be time to consider reversing what he perceives as a worrisome trend. "Is it time to reduce the number of functions in order to reduce the exposure?" he asked, referring to the proliferation of wiring- intensive in-flight entertainment systems, power ports for laptop computers, etc., which are installed for marketing purposes but which add little to the safety of the airplane. For example, there are about 26 miles of wiring in the B737, and more than 88 miles of wiring in the newer-design B767.

With respect to fuel systems specifically, Traficant hypothesized, "There must be a way to ensure there are no wires inside the fuel tank" (emphasis in original). He suggested gravity-fed fuel pumps as an alternative to electric pumps. Of interest, the Boeing [BA] B777 uses a sonar system to measure the fuel level in the airplane's fuel tanks, thereby obviating the need for the kind of fuel quantity indication system (FQIS) probes found in the TWA 800 accident aircraft, and which are now the subject of proposed inspections on B737s.

Fix today's problem today

However, it will be years before new designs with significantly less wiring, as suggested by Traficant, enter service. In the meantime, the industry is faced with an aging fleet, of which the TWA 800 accident airplane was a tragic example, where the politicians are concerned that the Federal Aviation Administration (FAA), as the ultimate guarantor of the safety of the flying public, may not be moving fast enough.

Kent Hollinger, chairman of the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC), the FAA-industry task force addressing the issue, said the Air Transport Association's (ATA) "Spec 117" outlining "best practices" for wiring has been distributed to all member carriers, as has a videotape version of the booklet. However, ATA represents only 25 U.S. carriers. AirTran [AAI], for example, is not a member, yet one of its airplanes recently experienced an in-flight electrical fire shortly after takeoff that, had it occurred at 30,000 feet and far from an airport, could have ended with far more serious consequences than an emergency landing. Even among the ATA's current member carriers, Rep. Fowler retorted, "not a single airline has fully implemented Spec 117."

The Department of Transportation's (DOT) Inspector General has been looking over the shoulder of the FAA's efforts, so to speak. Alexis Stefani, assistant DOT inspector general, told the legislators that the FAA needs to improve in three areas: implementing training and improved procedures in the field, putting more money into wiring research, and improving data collection to capture many wiring-related problems now believed to be going unreported.

"Without consistent reporting," Stefani observed, "the true health of the system will not be reported."

Recent changes to the Service Difficulty Report (SDR) system should help plug gaps (see ASW, Sept. 11 and Sept. 25). That is, assuming there is more uniform reporting among carriers, some of whom are not now reporting at all, on any item, much less wiring, and assuming the implementation of a code to clearly identify wiring problems.

Committee Concerns

Rep. Traficant expressed his concern that the FAA may not have electrical engineers in key positions to deal with the aircraft wiring issue. He asked for a by-name listing of the individuals working the problem and their credentials.