Wired for Disaster
Swissair 111 was wired for disaster in five specific respects:
2.1 The Specific Wiring – Aromatic Polyimide
The average jumbo jet has approximately 175 miles of wiring, some covered with a thin layer of insulation no thicker than three human hairs. One type of wire in particular has attracted the most attention; a general-purpose aromatic polyimide wire commonly known as Kapton. Kapton was trademarked by DuPont in 1966. Aromatic polyimide is the most commonly used wire insulation on many older Boeing and McDonnell Douglas airplanes that were built beginning in the late 1960s. It is lightweight, resistant to abrasion and cuts, is able to withstand high temperatures, and is flame and environmentally resistant. These properties were hailed as major breakthroughs when it was introduced in the late 1960s. But, within a few years, inherent dangers emerged. First, over time the insulation becomes brittle and cracks easily, allowing the conductor to be exposed. Second, the insulation is compromised if strict maintenance, marking and installation practices are not observed. Third, prolonged exposure of this type of wire insulation to moisture can also cause it to deteriorate. In any of these three scenarios aromatic polyimide is susceptible to arc tracking.
Arc tracking can occur when two cracks in the insulation are close enough together to allow the current to form a conductive path between them at temperatures that can cause the insulation to char and carbonize. This carbonization can turn the insulation into an electrical conductor, and, eventually, can trip a circuit breaker. When a pilot presses the switch to reset a tripped circuit breaker, an entire wire bundle can be disabled and potentially compromise the safety of an aircraft’s entire electrical system.
2.2 Data Mining
IASA set about gathering together as much data as possible in respect of aromatic polyimide wiring and soon realized the concerns stretched back over 20 years. This was not a problem confined to either the commercial or military realm as both had data warning against its continued use. Yet in spite of this, it remained the wiring of choice in hundreds of commercial aircraft both in the United States and abroad.
Even the FAA had issued Advisory Circulars warning airlines of its susceptibility to arc tracking, for example:
Advisory Circular 25.16 dated April 5th 1991
Aging, weathering, vibration and the normal wear and tear of maintenance sometimes cause chafing, abrasion, or deterioration of insulation, which can cause cracks or cuts that can expose the conductor… service experience of aromatic polyimide insulation, as presently constructed, documents a failure mode called "insulation flashover" where conduction at insulation breakdown areas has damaged or destroyed the wire or wire bundle in which it occurs. Also, other adverse effects have sometimes occurred as a result of this failure mode. Arcing on wire insulation, or "arc tracking" can result from electrolytic contamination of wire having insulation cracks or cuts that expose the conductor. It can also result from chafing damage that reduces the dielectric strength of dry insulation.
Whenever practical, aromatic polyimide insulation wires should not be used for high current carrying cables.
Advisory Circular 43.13-b dated September 8th 1998
Fracture of the insulation wall and penetration to the conductor of these materials by the stamping dies have occurred. Later in service, when these openings have been wetted by various fluids, serious arcing and surface tracking have damaged wire bundles.
These two documents along with many many others demonstrated not only that the FAA knew of the problem but as we shall see, were apparently reluctant to require a fleet wide removal of aromatic polyimide in spite of the growing data that it posed a threat to the safety of the flying public.
2.3 Military Experience of Aromatic Polyimide
In the mid-1980s, the Navy began experiencing problems with aromatic polyimide. In response, the Navy enlisted the assistance of experts from other military services and the Federal Aviation Administration (FAA) to better characterize the problems and develop possible solutions. Ultimately, FAA and each of the military services responded differently to the problems of aromatic polyimide.
The Navy started using aromatic polyimide in the mid-1970s, began noticing cracks and breaks in the topcoats of this insulation in 1980 and 1981, and undertook research to identify potential problems with its use. In 1984, researchers at the Naval Research Laboratory reported that moisture caused aromatic polyimide to break down when it was exposed to high humidity, moisture, or water for long periods of time. It also found that carbon deposits can form and build up between two cracks in this insulation after several arcing events, a process that ultimately trips a circuit breaker. When a pilot pushes in a tripped circuit breaker to reset it, an entire wire bundle can be disabled, potentially causing catastrophic results.
In December 1985, the Navy decided that aromatic polyimide would no longer be its wiring insulator of choice. Subsequently, the Navy selectively removed this wire insulation from parts of aircraft where it was most problematic, such as fore and aft flaps, wheel wells, and around unsecured seals that could leak. However, because the Navy still had a large supply of aromatic polyimide on hand, it continued its use on aircraft in areas that were not vulnerable to water infiltration. The Navy also took delivery of some McDonnell Douglas aircraft in 1988 that were built with aromatic polyimide wiring insulation that had been purchased before problems with this wire insulation were recognized.
2.4 Mobilizing the Issue & House of Representatives Aircraft Electrical System Safety
IASA initially met with the FAA in Washington D.C. on May 18th 1999 to discuss, among other things, the susceptibility of aromatic polyimide to arc tracking and the practice of using circuit breakers as ‘on/off’ switches that in an arc tracking scenario can exacerbate the potentially deadly situation. At that meeting IASA referred the FAA to Advisory Circular 25.16 dated April 5th 1991. A further meeting was held on September 7th 1999 to assess what progress (if any) in respect of the matters raised at IASA’s initial meeting with the FAA and also to discuss IASA’s formal participation on ATSRAC (Aging Transport Systems Rulemaking Advisory Committee). Representing the FAA Associate Administrator, Thomas E McSweeny and Beth Erickson, FAA Assistant Director Certification.
During that meeting an interesting comment was made by Beth Erickson in response to Lyn’s concerns that four years given to airlines to replace M-Pet insulation blankets (See Section 3 below). Her response was that the four year requirement for compliance was needed to ensure that damage to the wiring did not occur in a rush to replace the insulation blankets. So… let aircraft continue flying laden with materials that are known to propagate fire in order not to exacerbate a problem, that as you will see, according to the FAA Associate Administrator the FAA may not have had a large indication of safety problems.
The meeting took place just eight days before the House of Representatives, Subcommittee on Oversight, Investigations and Emergency Management, Committee on Transportation and Infrastructure began hearings in respect of Aircraft Electrical System Safety in Washington, DC.
Amongst those who gave evidence was DR. Bernard Loeb, Director, NTSB Office of Aviation Safety. Dr. Loeb was unequivocal in his assessment of the widespread nature of the problem.
Dr. Loeb. We also found wire bundles contaminated with semiconductive residues, metal drill shavings along the path where the center tank wiring was routed. In an effort to determine if these findings were unique to the Flight 800 airplane, or existed on other transport airplanes, the Board examined wiring on more than 20 other transport category airplanes and found accumulations of contaminants on wiring that included lint, grease, liquids, paper, metallic corrosion-inhibiting compounds, wire bundle clamps that cut into the wire when the rubber lining crumbles, shavings and cracks in the insulation of wire, deep enough to expose the conductor. These findings have raised the Safety Board's concerns about the safety of electrical systems as airplanes age. However, in recent industry meetings and seminars, operator personnel have questioned the merit of performing wiring inspections indicating that they have not detected significant discrepancies. This is certainly at odds with our findings.
The record also notes:
Dr. Loeb. We have
inspected at least 25 airplanes as a result of the TWA 800
investigation. Eighteen of these were airplanes that were essentially in
the desert in moth-balled conditions, or sitting there waiting for
disposition. They were older airplanes, many of them similar to the TWA
Flight 800 airplane. In addition, however, we had an opportunity to
investigate seven additional airplanes that ranked from relatively newer
or brand-new airplanes to fairly new airplanes that were actually in
service, but had experienced some sort of an event, an incident. In all
of them, we found some anomaly, either metal drill shavings or lint, and
other anomalies similar to that found in the TWA 800 airplane.
Mrs. Fowler. So in all 25 planes that you inspected you found some type of problem with the wiring?
Dr. Loeb. That is correct.
FAA Associate Administrator, Thomas E McSweeny, later took the stand and his comments together with those of Beth Erickson, FAA Assistant Director Certification, confused the situation. They confused the situation in the sense that their comments appeared to be at odds with what we as an organization had ascertained; that there was a problem stretching back many years and yet little or no pre-emptive action had been taken to mitigate it.
Mr. McSweeny. We have really looked at wiring over the years. In the—in the early 80s when Kapton was introduced and people started seeing problems, we really focused on it deeply. We spent efforts with the manufacturers, looked at it. We created a program at the Tech Center to look at it. We've had lots of employees over the years looking at wiring. So we've really focused on it as an issue kind of at the beginning because of our requirements to oversee the safety of any product that's out there in service… In that vein, they [White House Commission on Aviation Safety and Security] also recommend today looking at wiring. We think that was a very appropriate recommendation because while we may not have had a large indication of safety problems up to that point, we really need to make sure that problems don't get introduced as the airplanes age.
While we may not have had a large indication of safety problems up to that point, we really need to make sure that problems don't get introduced as the airplanes age. Aromatic polyimide had been banned by the NAVY fourteen years before Mr. McSweeny’s testimony and yet the FAA Associate Administrator, second-in-command, felt comfortable in saying that the FAA may not have had a large indication of safety problems up to that point. As mentioned above, this testimony is confusing.
As for the service life of aircraft wire, once again the McSweeny’s testimony is at odds with the data.
Mrs. Fowler. I think
we have all agreed from the testimony here today, and I want to make
sure you agree, that the noncomposite wiring that is used on aircraft
today does have a service life limit.
The NTSB’s final report into the TWA800 crash refers to a 1997 Lectromec report that documented the aging of Kapton wire insulation in various locations in U.S. Navy P-3 airplanes. This report indicated that wire insulation in areas exposed to sunlight and moisture could reach the end of its service life (chemically) within 1 year, whereas wire insulation in protected areas in the same airplane could survive for up to 10 years.
One of the battles we fought was getting the FAA to accept that whilst environmental and operations factors were critical, one also had to accept that different wires perform differently under such circumstances. Wire is not just wire in the generic sense. Beth Erickson confirmed this polarity in spite of the documented evidence, both from the FAA themselves [AC25.16 ‘Whenever practical, aromatic polyimide insulation wires should not be used for high current carrying cables’ Please refer to Section 2.2 [above] and countless others.
Ms. Erickson. Congressman Oberstar, as you pointed out, many of the things that we have found in our inspection programs to date have pointed out that across the various types of wire, the main issues really are design, how the wires are installed, whether the bend radiuses are too tight, whether the clamps are holding them in place for the vibration kinds of issues, whether they're routed so they don't get fluid from lavatories dripped on them. And then also in the maintenance area, you've pointed out several problems that could occur.
Erickson also made the following comments in a CNN report appeared October 11th 2000 that appeared at odds with the prevailing data:
“Cracked wires do not, in and of themselves, represent an immediate safety problem," Erickson said in a discussion of the agency's program to study aircraft wiring. But, she added, "they are of concern to us." Asked about reports that the cracked wiring found on the six retired airliners could mean some planes have hundreds of damaged wires, she insisted that assumption was incorrect. Those inspections targeted areas where wiring was under the most stress, areas where it was exposed to heat or cramped into a tight areas, she said. Those findings "can't be extrapolated to the whole of the aircraft," she said.
2.5 The Executive Office of the President
In response to the White House Commission on Aviation Safety and Security, the FAA formed a fact-finding committee in 1998 to evaluate the aircraft systems of the aging fleet and propose enhancements to current procedures. The Aging Transport Systems Rulemaking Advisory Committee (ATSRAC), which was composed of representatives from various segments of the aviation industry, focused its investigation on aircraft wiring. Although IASA was granted a non-voting role in ATSRAC the FAA felt that ‘passengers rights are presently represented sufficiently’. In spite of this IASA again met with the FAA on October 5th and November 23rd 1999.
IASA had anticipated a lethargic response from the FAA and accordingly had already attended meetings on May 18th 1999 as follows:
· Executive Office of the President, Science & Technology Policy at the White House LSR, EB, AVDW, JK and JTL met with Lee Ann Brackett (Congressional Liaison) and Stephen G. Moran (Space & Aviation).
To add further momentum to the issue, IASA realized that like aviation safety, the safety hazards associated with aromatic polyimide wiring were a matter of global concern, accordingly IASA attended a series of meetings in Europe in November 1999 to galvanize the issue. Those meetings included:
IASA’s May 18th 1999 meeting with representatives of the Executive Office of the President was the start of a long and fruitful relationship. The Clinton Administration had already started a review of commercial aviation with the July 25th 1996 creation of the White House Commission on Aviation Safety and Security (the Commission). The time was ripe for IASA to build on that commitment albeit we didn’t know it at the time.
The Commission was assigned three specific mandates: to look at the changing security threat, to examine changes in the aviation industry, and to look at the technological changes coming to air traffic control. It was created on the heels of the July 17th 1996 crash of TWA800, a Boeing 747-131, near East Moriches, New York, that claimed the lives of all 230 people on board.
In terms of aromatic polyimide wiring, although it wasn’t known at the time, the NTSB’s investigation of the crash of TWA800 would reopen the Kapton debate. When the NTSB delivered their final report on August 23rd 2000, the aging and arcing characteristics of aromatic polyimide were again front page news. The NTSB had hired Lectromechanical Company (Lectromec) to conduct laboratory research into the short-circuit behaviors of aromatic polyimide. Lectromec reported that it was susceptible to strong, energetic, arcing.
As discussed, IASA first met with representatives of the Executive Office of the President on May 18th 1999. That meeting, and those that took place subsequent to it, namely on December 10th 1999 and February 3rd 2000, set the stage for what would be a turning point in the aircraft wiring issue. The latter meeting culminated in the Executive Office of the President taking unprecedented action.
On May 10th 2000, the Executive Office of the President released a memo stating:
As a result of a review of existing research and wire safety efforts underway at FAA, DOD, and NASA and recent White House meetings including representatives of the International Aviation Safety Association, Lyn Romano and Edward Block, we have concluded that aging wiring is an issue of national concern that extends beyond aviation. Therefore, we are proposing to form an Wire Safety Research IWG that will become the focal point for wire safety technology in the U.S. This group will be responsible for ensuring that federal research is coordinated and communicated in a timely way to improve safety for air, space and other areas where aging wiring is a safety issue.
At the time of the memo’s release, preparations were underway for a symposium IASA would host in New York on November 17th/18th 2000. The symposium would bring together a host of experts from across the world and Charles Huettner, the President’s Senior Advisors on Science & Technology, not only agreed to speak at the symposium but to chose it as the venue to deliver the Wire Safety Research IWG report ‘Review of Federal Programs for Wire System Safety’.
The issue of aircraft wiring was high on the political agenda.
2.6 The TSB August 28th 2001 Flammability Recommendations
On August 28th 2001, the TSB issued Aviation Safety Recommendation A01-03 that required a certification test regime to evaluate aircraft electrical wire failure characteristics under realistic operating conditions and against specified performance criteria, with the goal of mitigating the risk of ignition.
In light of the formation of the May 10th 2000 formation of the Wire Safety Research IWG, the August 23rd 2000 NTSB report into the crash of TWA800 and the TSB’s three Aviation Safety Recommendations issued on August 28th 2001, IASA made arrangements to meet with the FAA in September of 2001.
The terrorist atrocities of September 11th 2001 are a seminal moment in our history. Not only did the heinous acts claim the lives of some 2800 people and leave thousands more to struggle to build their lives without their loved ones, but the world would never be the same place again. It soon became apparent that there were serious, and as it transpired deadly, flaws in the FAA’s regulation of aviation security. As in the case of aircraft wiring, serious discrepancies in the security of our nation’s airports had been the subject of many reports prepared by the Office of the Inspector General (OIG) and the General Accounting Office (GAO), and yet lessons were not learned and warnings were not heeded. It took the lives of the innocent for something to be done. The formation of the Transportation Security Administration heralded a new era in aviation security, one that the FAA was to play no part in.
Prior to the September 11th terrorist atrocities, the FAA had often been accused of possessing a ‘tombstone mentality’. Those who criticised the FAA would point to its propensity to react instead of being a proactive advocate of safety and efficiency. To those who chastised the critics, we have no comment.
2.8 Post 911
As a nation, we needed to respond to the dire anomalies that characterized our aviation security infrastructure. IASA did and to this day is in complete agreement. However, such efforts must be in addition to other initiatives that have the sanctity of human life uppermost in its minds. The tomes of data warning of the dangers inherent in aircraft wiring ultimately translates to more needless deaths if something isn’t done about it. IASA was told in no uncertain terms in 2001 that as far as the TSB’s August 28th 2001 recommendations were concerned nothing would happen. All one had to do was look to the newspapers for confirmation, on the day the TSB released their recommendations an FAA spokesperson stated that the FAA was unlikely to act on the TSB’s recommendations. As much as it saddens us as an organization, there are those who do not respect human life to the same degree we do.
2.9 NASA Takes the Torch
As with the May 18th 1999 meeting with representatives of the Executive Office of the President, an unexpected source of assistance was to come IASA’s way. The Wire System Safety IWG was co-chaired by William J. Harris of the National Aeronautics and Space Administration (NASA). IASA soon realized that NASA took the issue of wiring to new heights. Not only was NASA at the forefront of emerging technologies aimed at detecting wiring defects before they resulted in a serious incident or accident, they were also willing to ‘open their doors’ to IASA.
On May 29th 2002 Lyn Romano was invited to Kennedy Space Center to inspect the wiring of the space shuttle Discovery while the Shuttle was in a 20-24 month maintenance mode. Lyn kept a journal of her time at KSC, and states in respect of her first day:
This clarified for me just how I ended up at NASA. I suppose I was meant to witness first hand how NASA is addressing the wiring concerns they have been confronted with, in order to see for myself what they had been telling me for several months, since my initial communication with the gentleman at JSC. What was he telling me? Specifically, NASA is most concerned with providing the human beings that board their shuttles the highest level of safety humanly possible. The safety they deserve. We all know disasters happen, BUT, when there are means to ensure the safest possible environment, either in the commercial aircraft realm or the space shuttle realm, they need to be aggressively undertaken, something NASA has chosen to act on and not just talk about. Talking about it, rather then acting aggressively seems to be the course the commercial realm of aviation has chosen instead.
To be proactive is to act in a manner commensurate with a genuine desire to protect human life. It is not enough to hide behind ‘cost benefit analysis’, the formula used in assessing the feasibility of a particular safety enhancement that weighs the perceived benefit against the monetary investment required to implement it. In other words, even life has its price.
What NASA did was afford us an organization the opportunity to see best practice in operation. Again quoting from Lyn’s journal:
As I look around the mid-body section, I can see how much attention is being paid to ensure the bend radius of the wiring is smooth, as it “snakes” its way up, around and through the craft. Adequate wire separation is also apparent. This being a very “hot topic” item of discussion in the commercial aviation realm recently, I was quite impressed to see this vital safety enhancement already being tended to by NASA. The pristine conditions stunned me.
As an aside, we would like to take this opportunity once again to thank Bill Harris and Steve Sullivan for allowing us the opportunity to witness first hand your tireless dedication and commitment to excellence. In our opinion, you set the standard that those in the commercial realm would be wise to adopt.
2.10 A Piecemeal Approach to Aircraft Wiring
The FAA started in the way they have continued; a piecemeal approach to the problems associated with aromatic polyimide. In 2004 alone the FAA issued five dockets that all relate to wiring and yet there is no sign of a comprehensive all-encompassing program to eradicate the problem.
· October 27th 2004- FAA issued Docket No. 2003-NM-69-AD requiring ‘an inspection to detect arcing damage of the surrounding structure of the terminal strips and electrical cables in the avionics compartment, and repairing or replacing any damaged component with a new component.’
· Effective December 14th 2004 – FAA issued Docket No. 2001-NM-54-AD stating the ‘actions specified by this AD are intended to prevent moisture from entering through the rear of the connector of the ODUs located in the overhead baggage stowage racks, which could result in a short, damage to the connector pins, and consequent smoke and/or fire in the cabin’.
· Effective December 14th 2004 – FAA issued Docket No. FAA-2004-18572 ‘prompted by arcing between a power feeder cable and terminal board support bracket. We are issuing this AD to prevent arcing damage to the power feeder cables, terminal boards, and adjacent structure, which could result in smoke and/or fire in the cabin.’
· Effective December 14th 2004 – FAA issued Docket No. 2000-NM-32-AD ‘intended to prevent electrical shorting of the brake coils of the ATS, which could result in smoke in the cockpit and/or passenger cabin’
· Effective December 14th 2004 – FAA issued Docket No. FAA-2004-18573 ‘prompted by an incident in which arcing occurred between the power feeder cables and support bracket of the terminal strips. "We are issuing this AD to prevent arcing damage to the terminal strips and damage to the adjacent structure, which could result in smoke and/or fire in the mid-cabin compartment’."
To put the MD-11 into context, to our knowledge the MD-11 is the subject of more ADs than any other transport category aircraft in respect of electrical wiring problems and electrically stoked smoke and fire threats.
To this day the FAA has not mandated a certification test regime to evaluate aircraft electrical wire failure characteristics under realistic operating conditions and against specified performance criteria.
On this day seven years since the needless loss of 229 innocent people we renew our request for the FAA to act on the TSB’s August 28th 2001 recommendations.
 FAA wiring study finds improvement needed
 Thomas McSweeny, Associate Director FAA.