The airline industry is teetering on the cusp of uncertainty. And, as the saying goes, uncertainty begets anxiety.

The concern is about four major safety programs, the combined impact of which involves potentially hundreds of millions of maintenance man-hours and dollars to carry out. Exactly when these programs will be mandated by the Federal Aviation Administration (FAA) is a matter of widespread conjecture. FAA officials are acutely aware of the uncertainty and are working behind the scenes to develop a coherent and coordinated program. Indeed, the FAA has organized a "Tiger Team" to develop an integrated plan.

The four major safety programs involve electrical, fuel and structural systems, with new requirements for airplanes with 14 or more years of service. To recount briefly each of the four initiatives affecting transport-category aircraft:

1. Electrical system safety. This initiative has a mouthful of an acronym, EAPAS, which stands for Enhanced Airworthiness Program for Aircraft Systems. It involves zonal inspections of electrical wiring and interconnection systems (EWIS). These inspections were dubbed the enhanced zonal analysis program (EZAP) for wiring. The EZAP effort reportedly will commence in 2006, a two-year slide from the original plan to begin that effort this year (see ASW, May 5, 2003, and ASW, July 14, 2003). A subset of this effort involved a one-time detailed visual inspection of cockpit, electronics and equipment bay wiring, and power feeder cables (CEEPF). However, according to the June bulletin of the UK's Air Accidents Investigation Branch (AAIB), the CEEPF inspections have been folded into the larger EZAP effort .

2. Structural system safety. The second program involves widespread fatigue damage, or WFD. This effort requires operators to implement maintenance actions to prevent WFD before the airplane reaches a set number of flight cycles and/or hours. The problem of WFD from scribe marks scored into the aluminum during preparation for painting was recently the subject of FAA concern (see ASW, April 12, and ASW, June 7).

A corrosion prevention and control (CPCP) initiative is evidently on "hold" for the moment, although corrosion can contribute to WFD, as was evidenced in the fatal May 2002 explosive decompression of a China Airlines B747, which involved WFD aggravated by corrosion (see ASW, June 30, 2003).

3. Structural system safety. For aircraft with 14 or more years of service, the FAA wants damage-tolerance-based inspections incorporated into the aircraft maintenance programs. This initiative applies the damage-tolerance concept to structure outside of the pressure hull.

4. Fuel system safety. Under a Special Federal Aviation Regulation known as SFAR 88, manufacturers are required to conduct fuel system safety assessments and to implement required inspection and maintenance programs to ensure that the original design, intended to minimize the presence of ignition sources, remains intact through the life of the airplane. Since electrical components are found in fuel pumping and fuel level indication systems, there is a certain amount of overlap between the SFAR 88 effort and the EAPAS program.

An overall plan was expected to be published May 4 in the Federal Register, but that document, the subject of ongoing review within the FAA, the Department of Transportation, and the Office of Management and Budget, has been delayed. Imminent release is expected.

In effect, the timelines for these efforts are sliding to the right, sources say, with implementation dates later rather than sooner.

"We don't understand how big the elephant is we have to eat," said an industry official. He added that operators are prepared to implement the programs but don't at this moment know how much work will be involved or what the compliance schedules will be.

SFAR 88 is perhaps the most current case in point regarding uncertainty. To appreciate why, it is necessary to back up and recount briefly the recent history. Published in May 2001, SFAR 88 required the manufacturers, or type certificate (TC) holders, to conduct fuel system safety assessments. The objective was to prevent ignition sources by identifying areas in the fuel system requiring additional or enhanced maintenance and inspection procedures, as well as possible design changes. The design changes were to be implemented by airworthiness directives (ADs). Those companies holding supplemental type certificates (STCs) involving modifications and installations affecting fuel systems (mostly manufacturers) also were directed to conduct comparable fuel system safety assessments.

The TC holders were to submit their safety assessments for FAA approval by December 2002. Three months before that deadline, the FAA announced that it would allow for an "equivalent safety" means of complying with SFAR 88 through installation of a fuel tank inerting system. STC holders were granted a six-month extension to the original December 2002 deadline, and to have their safety assessments completed by June 2002. The FAA was supposed to have approved these TC and STC assessments and their associated implementation plans by February 2004. Implementation among operators and repair stations was to begin in December 2004. That implementation date is likely to slip to some time in 2005.

The reason is evident in a recent development. Industry officials have until June 28 to submit their comments on a policy the FAA proposed May 28 for approving the fuel system safety assessments and the related inspection and maintenance programs (see ASW, June 7)

This document introduced a new term, Critical Design Configuration and Control Limitation, or CDCCL. Under this concept, all fuel pumps become critical items, as are fuel pump wiring and fuel pump circuit protection devices. Operators must strictly comply with the manufacturer's maintenance instructions. This top-down discipline marks a big change from the current flexibility where operators, subject to FAA approval, can vary manufacturers' maintenance procedures to better accommodate their unique circumstances.

The CDCCL concept is sweeping in scope. Defined by TC and STC holders, CDCCLs can be subject to mandatory inspection and maintenance tasks. CDCCLs involve design aspects such as wire separation, explosion-proof features of a fuel pump, maintenance intervals for transient suppression devices, fuel quantity indication system (FQIS) wiring, minimum bonding jumper resistance levels, and so forth. Any maintenance actions or subsequent changes to the design must not degrade the safety level of the original design over the operational life of the airplane. STC wiring installed adjacent to original design wiring may well be categorized as safety critical under the CDCCL aegis.

One of the major problems is that SFAR 88 and the EAPAS-related wiring inspections overlap. This is evident in the caution contained in the FAA's May 28 proposed policy:

"In some cases, the maintenance evaluation of the fuel tank system may include elements of the electrical wire interconnection system (EWIS). Where electrical elements are common to both the fuel tank system and EWIS, resulting tasks and intervals should be compatible. Because there is a plan to separately address EWIS in future operational rules, care should be taken to properly identify an EWIS consideration versus the fuel tank maintenance consequences from compliance with SFAR 88."

(Emphasis added)

To discriminate between the two, a straightforward approach might be taken: any wiring that begins or ends in a fuel tank falls under SFAR 88. After all, SFAR 88 was based on the fatal 1996 center wing tank (CWT) explosion of TWA Flight 800. The National Transportation Safety Board (NTSB) concluded that current crossover in a bundle outside the tank was the pathway for the current through the FQIS wire into the tank, the tiny spark from which caused the vapors to explode.

Moreover, the May 28 proposed policy introduces a new division of fuel tank risk. It divides tanks into high and low exposure, with flammable vapors present in the tank more than 7 percent of the time dividing the two. The conditions in the CWT of the TWA jet made it a high flammability exposure event (empty tank, potential sparking sources not covered by fuel, high ambient temperature, air conditioning packs under the tank in operation adding more heat, etc.).

A tank with low flammability exposure is defined, in part, as one in which the fuel temperature rises less than 10� F above ambient during a four-hour operation on the ground with an 80 percent full fuel load.

One commentator said such a criterion "serves no useful purpose" because the mass loading of the TWA tank certainly was less than 80 percent. However, CWTs will not always be filled 80 percent or more with fuel. The amount carried in the CWT relates to an airplane's maximum zero fuel load. If CWT fuel is not needed for the planned flight, then all fuel will be loaded in the wings as a maximum zero fuel weight (ZFW) consideration - leaving the CWT in a high flammability state from shortly after air conditioning pack starts on a hot day.

The point here is that the provisos of the FAA's May 28 proposed policy seem sufficiently complex to confuse expert and layman alike.

To employ a sports team analogy, the players are perplexed and bemused by the still-evolving rules of the game and the changing timetable. The nature of the end game is not in sight. It could be soccer (the tank electrical safety initiative), American-football (the inerting option), or a little bit of each (the tank electrical safety effort for wing tanks and inerting for CWTs).

However, the size of the "elephant," as described by the industry official, is about to emerge. Various industry sources say the first AD from the fuel system safety reviews is about to be issued (i.e., within days). The overall schedule of what is to be required, and when, is anticipated to be published before the end of July (see related June 14 item at p. 8 on a July 8 Tiger Team presentation).

Tiger Team Tasking

Scope: Review all aging-related rules to develop an integrated plan for implementation.

Goal: Minimize the impact on operators while achieving the safety objectives.

Tasks:

• Baseline the current initiatives, considering compliance times and affected airplanes.
• Provide a focus on the operational impact and the "ability to comply."
• Prioritize the rules.

Source: FAA