White House Commission on

Aviation Safety and Security

FINAL REPORT TO PRESIDENT CLINTON

1.9. In cooperation with airlines and manufacturers, the FAA's Aging Aircraft program should be expanded to cover non-structural systems.

The average age of commercial airline fleets is continuing to increase. In 1975, few large commercial aircraft were in service beyond their original design life, typically twenty years. But with increased competition and growth in passenger and cargo traffic brought on by deregulation, service lives of dependable aircraft models were extended through expanded maintenance and overhaul programs. By the year 2000, more than 2,500 commercial aircraft in the United States may be flying beyond their original design life.

In 1988, a Boeing 737 in Hawaii suffered severe structural failure of its forward fuselage sections due to corrosion not visible during normal maintenance inspections. As a direct result of this accident, the FAA greatly expanded its structural integrity inspection program and formed the Airworthiness Assurance Working Group (AAWG). Its focus has been almost exclusively on structural integrity, and the effects of structural corrosion and fatigue. The programs in existence under the AAWG have been effective and are considered adequate to deal proactively with the structural problems associated with aging commercial aircraft.

However, much less is known about the potential effects of age on non-structural components of commercial aircraft. Non-structural components include electrical wiring; connectors, wiring harnesses, and cables; fuel, hydraulic and pneumatic lines; and electro-mechanical systems such as pumps, sensors, and actuators. Neither the manufacturers nor the commercial airlines consider the aging of non-structural components to pose serious safety problems primarily because they consider their redundancy, replacement upon failure, and periodic, programmed maintenance to be sufficient to assure aircraft safety.

The Commission is 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 age. To address this, the Commission recommends that the FAA work with airlines and manufacturers to expand the aging aircraft program to include non-structural components, through steps including: full and complete tear-downs of selected aircraft scheduled to go out of service; the establishment of a lead-the-fleet research program; an expansion of the FAA-DoD-NASA cooperative aging aircraft program; an expansion of programs of the Airworthiness Assurance Working Group to include non-structural components; and encouraging the development of modern technical means to ensure and predict the continued airworthiness of aging non-structural components and systems. _