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Preventing Fretting Damage Becomes Increasingly Critical as Aircraft Age 20 pages. [PDF 107K]
Fretting is a combined form of wear, fatigue and corrosion that can lead to premature mechanical failure at loads well below structural design limits. It is a time-based failure that will require increased attention as the transport-category
aircraft fleet continues to age.
On Sept. 14, 1997, the pilot of a Lockheed Martin F-117A felt an abnormal vibration when he initiated a climb during a flyover at 700 feet and 380 knots at an air show at Martin State Airport near Baltimore, Maryland, U.S. The U.S. Air Force stealth fighter then abruptly rolled to the left and pitched nose-up.
Age-related Failures of Aircraft Wiring Remain Difficult to Detect 16 pages. [PDF 212K]
Maintenance technicians are familiar with the types of aircraft-wire failure caused by chafing, cutting and other visible forms of damage. When such damage is observed, the wire usually is repaired or replaced.
Upper-wing damage was found during the walk-around inspection of a Fokker 100 (F-100) that landed at London (England) Stansted Airport after a flight from Amsterdam, Netherlands, on Oct. 12, 1995. The edge of the no. 5 lift-dumper (spoiler) panel
on the left wing was bent upward, said the U.K. Air Accidents Investigation Branch (AAIB).
As airframes grow older, accumulated fatigue and corrosion degrade their strength, but many airline-type aircraft are being flown well beyond their original design-service objectives. These aircraft were designed so that the majority of defects can be found by inspection while the aircraft is still strong enough to carry normal flight loads. Early detection of problems is made possible by a variety of technologies and by maintenance and inspection programs tailored to detect defects identified through operating experience.
Report Recommends Team Inspections, Checklists in Repair Station Oversight 20 pages. [PDF 145K]
In response to concern about work performed by some holders of repair station certificates, the U.S. General Accounting Office (GAO) conducted a review of the U.S. Federal Aviation Administration’s (FAA’s) oversight of repair stations and in October 1997 published the results in Aviation Safety: FAA Oversight of Repair Stations Needs Improvement.