Safety News

Training, inspection at heart of new wiring task force recommendations: The way forward on aircraft wiring safety is at a critical juncture, with enormous implications for manufacturers and operators in terms of the cost and labor burden.

A U.S. government-industry task force is considering two options. One places primary emphasis on technician training, and the second emphasizes new inspections of installed wiring.

The schedule for any wiring-specific inspections is a matter of considerable concern, as the FAA is mandating structural inspections of older aircraft, i.e., those with 14 or more years service. to minimize out-of-service time for all affected aircraft, the structural and wiring schedules must be coordinated.

"We will object to any arbitrary interval that will force special visits" of aircraft to maintenance facilities, declared Ric Anderson, who represents the Air Transport Association on the government-industry task force known as the Aging Transport Systems Rulemaking Advisory Committee or ATSRAC.

Kirk Thornburg of Northwest Airlines said that he was "particularly concerned" that the wiring work is done when the airplane is opened up for other activity, such as the aging aircraft structural inspections.

Fred Sobeck, a senior FAA official on ATSRAC, responded, "We are sensitive to that and want to make it easy for the operator to comply with both rules."

Scheduling ultimately may be less contentious that what the FAA may require to assure the safety of wiring systems in an aircraft of any age. Two options were debated vigorously at the ATSRAC’s April 24 meeting. That meeting was characterized by revelations that some of the committee members had written the FAA objecting to regularoty changes proposed by the very committee on which they sit, the study of which they had previously voted to undertake. The industry objections strike at the heart of how much emphasis should be accorded in FARs to wiring as an aircraft-level system, as opposed to wiring as a subset of other systems.

The inspection options under discussion fall short of the ATSRAC’s earlier concept. In previous meetings, the ATSRAC endorsed improved training on electrical wiring for maintenance technicians, and it called for a new battery of general, visual, and detail visual inspections (GVI/DVI) by zone in the aircraft or aircraft wiring. Known as EZAP, for enhanced zonal analysis program, these inspections were envisioned as a subset of a broader activity, including aircraft structure and other systems, known as EAPAS (enhanced airworthiness program for airplane systems).

In its original concept, EZAP envisioned an analysis of all wiring installed in the aircraft, in which a decision matrix would be used, such as whether the wiring is located next to combustible materials, whether it’s within two inches of primary and backup flight controls, and so forth, to determine which wires would be identified for added GVI and DVI scrutiny. Analyzing all wiring installed during original manufacture, or subsequently retrofitted into the aircraft under supplemental type certificate modifications, was deemed prohibitively expensive when combined with the recommended technician training. ATSRAC discussions have focused on initial EZAP-type inspections of cockpit wiring, electronic and equipment bay wiring, and power feeder cables.

Even with the reduced scope, any regulatory activity for improved maintenance technician training and for conducting EZAP inspections must be justified on cost-benefit grounds.

"We want to implement the full suite of ATSRAC recommendations, but it it’s not cost-beneficial, we can’t do it," said ATSRAC executive director Charles Huber. Huber, who also is an FAA official, said any proposed FAA rulemaking involving costs that exceed benefits "is DOA [dead on arrival] at OMB [Office of Management and Budget]."

Producing a credible cost benefit for wiring is particularly challenging, because there is no uniqued code for recording wiring-specific failures in the service difficulty reporting system and in other maintenance-related databases. Therefore, quantifying the cost of an unscheduled landing–and showing the benefit of avoided unscheduled landings–is a Catch 22. The number of flight diversions or turnbacks cannot be directly attributed to wiring because there is no code for reporting wiring problems.

Moreover, the benefits of any safety initiative typically are related to an accident, and the FAA does not presently have an accident to cite as justification for improved training and inspections related to wiring. The 1996 explosion of TWA Flight 800, a Boeing 747, was used to justify the change-out of metalized Mylar thermal acoustic insulation blanketing in the fleet of Douglas-built aircraft. While faulty wiring was involved in both cases, and accidents frequently can involve a multiplicity of contributing factors, an accident can only be used once for rulemaking purposes, FAA officials said. EZAP inspections could cost $100 million to $250 million or more. Wiring faults were seminal to the TWA and Swissair disasters. With a combined death toll of 459 passengers and crew, with the statistical value of a life of $3 million, those lives saved (or deaths avoided) would provide more than $1.3 billion in benefit.

Lacking an "unused" accident and the challenge of producing a credible cost benefit, ATSRAC members are looking at how existing rules can be capitalized upon to make progress.

"If we’re making use of an existing rule, we don’t have to cost it out," Sobeck said. For example, Part 121 of the FAA regulations, which applies to scheduled carriers, requires them to conduct maintenance training not only for their own personnel fur also for maintainers at repair stations to whome maiantenance may be "outsourced." these repair stations are covered by Part 145 of the regulations.