Mx Safety

The TWA Flight 800 disaster in many respects reflects a failure of maintenance, and the National Transportation Safety Board (NTSB) issued a press release as the 10th anniversary of the crash approached.

The NTSB remains disappointed that fuel tank inerting has not been mandated. It does not appear likely that it ever will, given the fierce industry resistance (see AM, July 2006, p. 10).

The NTSB's 400-page investigation into the tragedy, issued in August 2000, recounted numerous problems with old systems on the B747. The airplane departed New York's JFK International Airport with many reading lights burned out in the cabin, a missing flap track canoe fairing, the number 3 engine thrust reverser was locked out, the leading edge flap camber (cautionary) light illuminated when the leading edge slats were in the retracted position, and one of the airplane's two weather radars was inoperative. Before takeoff, the fueling system had to be turned off and the airplane had to be pressure-fueled manually. Suffice to say, without benefit of the Minimum Equipment List (MEL) proviso, and the virtue of deferred maintenance made possible to the redundancy of systems, the airplane would not have made the flight.

The biggest finding regarding maintenance and aging concerned the wiring, regarding which the NTSB report is instructive:

"Several potentially unsafe conditions were found in and near the electrical wiring from the accident airplane, including cracked wire insulation, metal shavings adhered to a floor beam along with the FQIS [fuel quantity indicating system] wires would have been routed ... In addition ... several repairs that did not comply with the guidelines in Boeing's SWPM [standard wiring practices manual] were found in the accident airplane. Noncompliant repairs included the use of an oversized strain relief clamp on the terminal block of the No. 1 fuel tank compensator, which did not adequately secure the wires; numerous open-ended (rather than sealed) wire splices, which exposed conductors to possible water contamination; several wire bundles containing numerous wire splices on adjacent wires at the same location; and excessive solder on the connector pins inside the fuel totalizer gauge ..."

The findings concerning old wiring led to the creation of Job Aid 1.0, by which the FAA outlined maintenance practices for wiring systems (see AM, March 2006, p. 6), and the FAA has proposed fleetwide inspections of wiring to assure that practices and conditions of the type found on the TWA and other aircraft are not repeated (see AM, March 2006, p. 24).

Thus, 10 years after the accident, it could be argued that if TWA 800 changed anything, it is in regard to wiring maintenance. Sadly, 230 people died to energize this wake-up call for better wire husbandry.