Foreword
Executive Summary
Specific Fixes, But A General Problem
Commercial Aircraft Wiring Problems - From Disturbing Incidents to Catastrophes?
Military Aircraft Wiring Problems - Been There, Done That
Systemic Failures - A Threat Not Fully on the Radar Screen
Remedies - Ways to Bring Focus on This Issue, and to
Share Government Resources Better on the Next Issue
Glossary
Appendix

• Following discovery of electrical arcing from chafed wires, the Federal Aviation Administration (FAA) has ordered grounding of Boeing 737 aircraft and immediate wiring inspections.
  
  
• Military and industry documents show that wiring problems may be much more widespread than just the issue of chafed wiring in the wing fuel tanks of 737 aircraft. Wire insulation failures - cracking, crazing, nicks spreading 360 degrees around the wire, high flammability, toxicity, softness at high temperatures - have been discovered in the past even without chafing.
  
  
• The military has been aware of serious wiring problems on its aircraft since at least the early 1980s. Problems were found not just with chafing, but also with degeneration of the insulation surrounding wires. Cracking of insulation was causing sparks and electrical problems.
  
  
• Faulty wiring is a prime suspect in the explosion of TWA Flight 800 in 1996. That aircraft had a type of wire, Poly-X, that the military partially replaced on Navy F-14 aircraft due to cracking. The aircraft also had another type of wire, extruded Teflon, going into the fuel tanks. The manufacturer had discovered cracks in this type of wire over a twelve year period.
  
  
• Following the crash of ValuJet 592 in May 1996, a maintenance worker for ValuJet reported to the FAA that wiring on the DC-9 that crashed was notoriously bad and had suffered numerous cracks and shorting out.
  
  
• A new-technology wire that has tested far better than the older types of wire is still not the standard wire specified in military specifications or FAA standards.
  
  
• A Defense Department wiring expert who raised the issue of faulty wiring on military aircraft in the early 1980s was retaliated against and fired.
  
  
• The government needs to initiate a comprehensive, high-level review of problems with wiring in both military and commercial aircraft to try to identify, at a minimum, the worst trouble spots.
  
  
• To prevent these kind of problems from escaping sufficient scrutiny in the future, improved information and investigation sharing are needed between the FAA and NTSB, on the one hand, and the military services on the other. More funding is needed for FAA inspectors, and the military should stop keeping its accident safety investigations secret.
  
  
• Protections should be improved to prevent bureaucracies from retaliating against those of their employees who speak out to try to fix a problem, and to encourage the agencies to listen to the message rather than shoot the messenger.

Specific Fixes, But A General Problem

In the last week, the Federal Aviation Administration (FAA) issued an urgent directive that older Boeing 737s must now have their wing wiring inspected immediately, and gave 60 days for the inspection of wiring in 747s and 767s. Over the past few months, the FAA issued directives requiring inspections and wiring fixes in 737s and 747s. Yet according to government and industry documents, the military has long known about inadequate wiring and its potentially catastrophic consequences - wiring that is still found on these and other commercial and military aircraft flying today. This wiring is found throughout the aircraft, not just in the wings. Aircraft manufacturers have downplayed the significance of these wiring problems for commercial aircraft.

This documented history of known electrical problems and failed wiring, combined with recent FAA and National Transportation Safety Board (NTSB) action on specific wiring problems, calls for immediate broader action. The government needs to look at faulty wiring as a major problem, not just a matter for fixes limited to specific problems in 737 wings.

Broken or cracked insulation on wiring, creating sparks or incorrect electrical signals, has already caused a variety of electrical problems gravely endangering aircraft in flight. Arcing from wires with broken insulation can burn holes through nearby metal. Some Boeing aircraft have had in-flight electrical problems with autopilots and cargo doors.¹ Although the NTSB has not yet formally issued final conclusions from its investigation of the explosion of TWA Flight 800 in July 1996, faulty wiring remains a prime suspect. In the interim, the NTSB has urged wiring inspections. One ValuJet whistleblower's description of faulty wiring on ValuJet Flight 592 following its crash into the Florida Everglades, raises serious concern about the state of aircraft wiring and the possibility that it may have played a role in that accident.

Some wiring problems may be caused by physical chafing, often from vibration, that would split even wires whose insulation was otherwise acceptable. But both cases of wiring failure are wiring issues needing more attention.

On the military side, wiring problems were so severe in the 1980s on the Navy's F-14 fighter - at one point F-14 crashes due to various causes were so high that Congressional hearings were held² - that many aircraft had to be partially rewired or taken out of service.³

The numerous electrical "anomalies" and unexplained crashes that aircraft have suffered often cannot be decisively proven to be caused by wiring problems - as many people who have experienced hard-to-track-down electrical problems in their automobiles can appreciate. Most wiring failures do not lead to crashes, since not all wiring is crucial to flight control systems or fuel tank safety. But the potential for disaster is always there, and will only get worse as aircraft age - two years from now more than 2,500 commercial aircraft in the United States may be flying beyond their original design life⁴.

Despite a record of years of electrical problems, and knowledge that wiring with identified problems is still found on many commercial and military aircraft, the government has yet to review comprehensively the track record of wiring types and acknowledge the potential scope of wiring hazards. The FAA has begun to look at wiring issues more, but an accelerated, government-wide initiative is needed. Information sharing between the FAA, NTSB, and military agencies can and should be expanded to improve prevention of air accidents.

The White House Commission on Aviation Safety and Security urged expanded FAA action on wiring in its 1997 final report. The report drew a parallel between the earlier overdue action on potentially catastrophic "structural" failure in aircraft, and current sluggishness on wiring and other "non-structural" areas. Warning signs on structural problems were not caught by normal maintenance and oversight - it took part of a Boeing 737 aircraft's shell ripping off in flight to spur adequate action on structural failures. Compared to structural issues, the Commission said, ". . . much less is known about the potential effects of age on non-structural components of commercial aircraft," including "electrical wiring; connectors, wiring harnesses, and cables. . . ." Despite industry optimism, the Commission was:

concerned that existing procedures, directives, quality assurance, and inspections may not be sufficient to prevent safety related problems caused by the corrosive and deteriorating effects of non-structural components of commercial aircraft as they age⁵.

Unfortunately, wiring problems might have received earlier and greater attention from government agencies if the initial reaction to "the messenger bearing the bad news" had been to listen rather than retaliate. After former Pentagon whistleblower Ed Block long ago raised the danger posed by certain wires on military aircraft - as part of his job as a wiring expert for the Defense Industrial Supply Center - he was fired⁶. The troubled wires he spotted in the early 1980s are still on aircraft, and one of their inadequate successors is still being put on aircraft.

Commercial Aircraft Wiring Problems - From Disturbing Incidents to Catastrophes?

Cracked wiring causing short circuits or sparks is a prime suspect in one recent commercial aircraft disaster, and raises dire warnings in another:

• The National Transportation Safety Board (NTSB) has yet to release its final report on the TWA 800 mid-air fuel tank explosion, but based on its investigation to date has urged the Federal Aviation Administration (FAA) to order inspections of wiring not just in Boeing 747 fuel tank wires but also wires on some Boeing 727, 737, 757, and 767 aircraft. (See Appendix A). The FAA has recently issued limited directives to re-inspect, shield, and separate certain wires on Boeing 737 and 747 aircraft. (See Appendix B). Long before the TWA 800 crash, a Boeing 737 sharing similar fuel system wiring suffered a catastrophic fuel tank explosion on May 11, 1990 in the Philippines.
  
  
• The NTSB concluded that the cause of the fire on ValuJet 592 was self-ignition of oxygen canisters in the cargo hold⁷. But an anonymous whistleblowing ValuJet maintenance worker called the FAA and described extraordinary wiring problems on the aircraft that crashed, including multiple electrical failures and shorting wires in the days leading up to and the day of the crash. (See Appendix C). Five days after the ValuJet crash, FAA released a directive - months in preparation - requiring inspection of cockpit wires "to prevent the potential for fire and uncontrolled smoke throughout the cockpit due to damaged electrical wiring."⁸

The whistleblower claims in the telephone call record that he and other ValuJet workers knew that Flight 592 aircraft ". . .904's wiring was notoriously bad" and that ". . . any wire bundles that had to be moved would cause the wires to break and short out." Circuit breakers on the aircraft had been bypassed. As homeowners know, circuit breakers are vital to prevent electrical fires.

Whether or not wiring was a part of the problem, at a minimum these astounding allegations raise serious questions about the condition of aircraft wiring, maintenance violations in the airline industry, and adequacy of oversight. At worst, the revelations could mean that wiring was the chief crash culprit, and escaped notice. The FAA reported the allegations to the NTSB, but normally the NTSB would not spend resources trying to track down an anonymous whistleblower. In this case the NTSB stated that it did check circuit breakers on other ValuJet aircraft but did not find more bypassing.⁹ The whistleblower's allegations were not directly addressed in the NTSB final report.

Problems have been discovered on various types of wire used on commercial and military aircraft. Particular wires mentioned here serve to illustrate the potential scope of the problem, but other wires may be troublesome too. Poly-X, a wire called "miserable" by military maintenance specialists, was originally installed on many Boeing 747s - including TWA 800 - and McDonnell Douglas DC-10s, another jumbo jet¹⁰. (See Appendix D).

TWA 800 also had another wire type going into its fuel tank called extruded Teflon, which was meant to carry only low-voltage current. Meeting minutes attached here in Appendix E reveal that - as long ago as the early 1980s - Boeing itself said that it had experienced cracking problems over a twelve year period with extruded Teflon. Yet the wire was still on TWA 800. Since it usually takes a chain of events to cause a crash, cracking in just one wire type would be less likely to cause a fuel tank explosion. But cracking in two wire types - hypothetically, Poly-X and extruded Teflon - could allow high voltage electricity to jump to low voltage fuel tank wires and cause an explosion.

Documents show that the military was aware of very serious problems with Poly-X and some of its successors, yet Boeing and McDonnell Douglas have argued that the wires' problems are not serious. (See Appendix F). It would be prohibitively expensive to replace all the questionable wiring on commercial aircraft, since it is hard to access in many places, so aircraft manufacturers and airlines have an interest in keeping the old wiring in place. However, a comprehensive review of all wiring problems could identify more of the crucial weak spots that could be selectively fixed. In theory, it might be less costly for an airline to do more fixes now rather than have more aircraft crashes.

Military Aircraft Wiring Problems - Been There, Done That

Poly-X was used on many military aircraft in the 1970s and 1980s, including on F-4s, E-2s, S-3s, A-6s, and F-14s. The company that produced it, Raychem Corporation, was the ". . . sole source QPL. [Qualified Products List] supplier of virtually all airframe wire used by the military . . ."¹¹ at one point in the mid-1970s. The Navy requested $354 million to fix the problems it found with the wire. The budget justification document reported that:

Numerous wiring harnesses made of "POLY-X" wire have had an abnormal insulation aging, embrittlement and cracking resulting in wire-to-wire shorts, particularly during the presence of water.... Some of the wire and connector failures have been observed as spurious signals on control wires causing spoilers to stick in the up position, inadvertent autopilot commands and power shorts which disable the autopilot completely. (See Appendix G).

An independent industrial committee investigating the issue found:

Flight-ready aircraft that were wired with Poly-X wires exhibit very frequent radial splits and cracks in every location where observed on F4, A6, E2C and F14 aircraft. These insulation splits usually expose the conductor and severe conductor corrosion is found. . . . Harness and wire bundles have or contain severely cracked Poly-X wire along with unaffected Kapton insulated wire. (See Appendix H).

While admirals described "significant maintainability problems and a reduction in combat readiness due to Poly-X wiring" (see Appendix I), Navy aircraft maintenance workers summed it up simply: "Poly-X sucks." (See Appendix J).

Faulty wiring in aircraft has caused other serious problems besides just fuel tank explosions. A six month study in the 1980s found 800 autopilot malfunctions on KC-135 tanker aircraft, equivalent to the commercial Boeing 707, which were wired with a PVC type wire different than Poly-X. (See Appendix K). Full rolls of the aircraft to left or right while on autopilot were found to be "due to broken wires." A one-time inspection discovered that almost a quarter of the aircraft had faulty wiring. In November 1997, Air Force One - at the time a Boeing 707 variant - carrying First Lady Hillary Rodham Clinton on a trip to Asia had to conduct an emergency landing after frayed wiring caused warning lights to come on.¹² Many KC-135s, other military 707 variants, and 707s in commercial service are still flying. Again, commercial incidents echoed military ones: a 1992 uncommanded roll while on autopilot caused a cargo 747 to dive 10,000 feet. The problem was caused by stray electrical signals, a hallmark of faulty wiring. The NTSB asked Boeing to redesign the autopilot system.¹³

Raychem replaced Poly-X with another wire, Stilan, but it also had problems and production was terminated. (See Appendix J and Appendix O). Then yet a third product produced sole-source by Raychem Corporation, Raychem 55, was declared in various Military Specifications as the preferred or only wire to use, and has been put in new military aircraft ever since. But Raychem 55:

• has some of the same cracking problems as Poly-X (See Appendix J).
• is excessively flammable, smokes very badly (See Appendix L).
• and is toxic when it burns (See Appendix M).

Apart from safety concerns, a problem with Military Specification 5088's leading to use of Raychem 55 is that the wire is a sole-source product, limiting the government's ability to shop around. In one application Raychem was quoting the government $31.00 per foot for Raychem 55, versus the $1.40 price of another wire that was found to be a "totally acceptable" substitute. (See Appendix N and Appendix O).

A memo from the Defense Industrial Supply Center, an agency that supplies materials to the military services, charged that "There are strong indications that Government personnel may be directing procurement to Raychem 55," suggesting they were skewing the procurement process, including writing military specifications so that Raychem 55 would be bought instead of superior products. (See Appendix N).

Government and industry have jointly developed a new wire called composite Teflon-Kapton-Teflon wire that shows far superior results than Raychem 55, according to various studies, including a comprehensive report by McDonnell Douglas and the Air Force, yet commercial specifications have not been re-written to encourage use of the improved product. (See Appendix L).

Systemic Failures - A Threat Not Fully on the Radar Screen

Systemic problems may help explain why wiring problems have not received the full attention they appear to have needed over the past two decades. The biggest problem may be that the FAA and NTSB on the one hand, and military agencies on the other, have not communicated and shared data with each other sufficiently. Not only are some aircraft in use in both commercial and military fleets, but components such as wiring are shared too. If both sides do not have a full set of information, one or the other will be missing key information.

Similarly, information-sharing between the military and aircraft manufacturers could be improved. Boeing noted that it was ". . . not aware of any requirement or procedure for the DOD to notify us of problems experienced on aircraft not manufactured by Boeing" - even though wiring trouble could be spotted on other manufacturers' aircraft using the same type of wiring as Boeing. (See Appendix F).

A related problem is that the military does not normally release its full safety investigation reports, merely its legal assessments, which do not include all the information in the safety investigation. Defense Secretary Cohen recently spoke favorably about releasing more investigation results.¹⁴ With secret investigations, it is particularly hard to assure the adequacy of the investigations and apply their lessons elsewhere. Senators Ron Wyden (D-OR) and Gordon Smith (R-OR) had to go to the extreme of holding up the confirmation of a new Chairman of the Joint Chiefs of Staff in order to get the Air Force to re-open a C-130 crash investigation that it had closed without a conclusion.¹⁵ The Senators also had to bring great pressure to get the Air Force to break precedent and cooperate with outside NTSB investigators. The C-130 has experienced 71 in-flight total engine shutdowns, almost half of which had an "unknown" cause in closed investigations, and 24 of which were attributed to the electrical system.¹⁶

In a rare instance, the Air Force did permit the NTSB to lead the investigation of the CT-43A that crashed with Commerce Secretary Ron Brown and his delegation on board in 1996. The Air Force CT-43A is equivalent to a commercial Boeing 737. But the Air Force only cooperated after deciding that "the NTSB had both superior expertise in this particular aircraft and also a compelling interest in discovering whether factors in the CT-43 crash could resolve the cause of [commercial 737 crashes]."¹⁷ This cooperation and sharing of years of experience on both sides can and should be fruitfully expanded.

NTSB and FAA crash expertise may be particularly useful because pilots and line officers who are not dedicated crash experts often lead Air Force crash investigations, according to a former Air Force safety official and NTSB investigator, Alan Diehl. Diehl has even called for independent investigations of military accidents: "Nobody should be allowed to investigate themselves, [and] certainly [not] the Defense Department. . . . Investigators need to be independent of the people they are investigating."¹⁸

Remedies - Ways to Bring Focus on This Issue, and to Share Government Resources Better on the Next Issue

Some might ask, if wiring is such a problem, why aren’t we seeing more aircraft crashes? The short answer is that it usually takes multiple failures to bring down an aircraft, some level of redundancy is built into most aircraft. But the real answer is that if you are a passenger on any plane "tripwired" with faulty wiring, that's one faulty wire too many. The government needs to improve assessment of the potential dangers posed by wire failures. Systemic failures that have allowed wiring to escape sufficient scrutiny suggest the following remedies:

• Acknowledge the potential scope of the problem. In order to gain high-level focus and to bring together government-wide experiences, coordinate action on wiring issues in one office.
  
  
• Conduct an immediate, government-wide, joint FAA, NTSB, and military assessment of wiring problems, correlating all commercial and military crashes, electrical "anomalies," and maintenance findings with data on which aircraft wires are where. This could help find, at a minimum, the worst trouble spots. Conduct complete teardowns of various aircraft to develop a representative but thorough picture of the state of wiring in aircraft.
  
  
• Develop procedures for increased sharing of accident information between the military and the FAA and the NTSB.
  
  
• Conduct joint NTSB/military investigations of military crashes and include more crash experts in military investigation teams.
  
  
• Reverse the decline in FAA training funding. The General Accounting Office has reported that "Our work has shown persistent problems with FAA's training of inspectors. Specifically, inspectors have been unable to take courses that they believe are necessary to perform their inspection responsibilities. . . . Decreases in FAA's overall budget have reduced the funding available for technical training by 42 percent from fiscal years 1993 through 1996."¹⁹ Increase funding for FAA training and, specifically, expand training of government accident investigators from all agencies in wiring issues.
  
  
• Release the full results of military accident investigations, and allow for independent review of findings.
  
  
• Update FAA standards in the Code of Federal Regulations and modify Military Specifications quickly to meet the superior performance standards of the latest composite wire.
  
  
• Improve procedures to prevent retaliation against whistleblowers or those trying to fix a problem from the inside.

GLOSSARY

WIRES Military specifications can be written so that they refer to only one product. The digits after the slash can distinguish one product from another.