Maintenance

Maintenance Overview | Sample Maintenance Program | Aging Aircraft

Maintenance Overview

A key element of aviation safety, commercial aircraft maintenance is a detailed process performed by only the highest trained and qualified individuals. It is also a process that allows for no shortcuts. Maintenance crews spend roughly 3.5 labor-hours working on a plane for every hour that plane is in flight. That type of maintenance does not come inexpensively - U.S. airlines spend more than $10 billion annually just to keep their fleets in top operating condition.

Manufacturers and airlines work together to develop maintenance programs that must be reviewed and approved by the FAA. Maintenance programs must include an inspection and replacement schedule that addresses the effects of aging.

Major U.S. airlines do most of their own maintenance, though they do contract out to independent shops, both domestic and foreign. All repair stations the airlines use must be FAA-approved, including foreign repair stations; and no matter where the work is done, the airline itself retains ultimate responsibility for the quality of the work. In addition, all parts used in maintenance - whether by airlines or repair stations - must be FAA-approved.

Between regular scheduled maintenance checks, computers onboard the aircraft monitor the performance of aircraft systems and record such things as abnormal engine temperatures and fuel and oil consumption. In the newest aircraft, this information is transmitted to ground stations while the plane is in flight. This allows the identification of potential problems before they result in a systems failure.

Sample Maintenance Program

A typical airline maintenance program involves the following (and much more):

• A visual "walk around" inspection of an aircraft's exterior several times each day to look for fuel leaks, worn tires, cracks, dents and other surface damage; important systems inside the airplane also are checked;
• An inspection every three to five days (A Check) of the aircraft's landing gear, control surfaces such as flaps and rudders, fluid levels, oxygen systems, lighting and auxiliary power systems;
• A check every 12-17 months (C Check) during which aircraft are opened up extensively so inspectors can use sophisticated devices to look for wear, corrosion and cracks invisible to the human eye; and
• A major check every three-and-a-half to five years (D Check), during which aircraft are essentially taken apart and put back together again, with many components replaced.

Aging Aircraft

Aircraft age is not a matter of years, but hours. The age of an aircraft is based on the number of takeoffs and landings made and the number of hours the aircraft has flown, not its numeric age.

Like automobiles, aircraft require more attention as they get older, but airlines and manufacturers work to make sure they are safe no matter what their age through extensive preventative maintenance.

Although older planes had been inspected more often than newer ones, the airlines adopted a new maintenance program to further assure the safety of older planes in 1988. Now, certain parts of an aircraft�s basic structure (rivets, aluminum skin, door and window frames, etc.) are replaced or modified automatically when the aircraft reaches certain time or operational thresholds. The work is timed to be done before corrosion, cracking and stress problems can occur.

In 1998 the FAA announced that it would expand its aging aircraft program to include aircraft systems. The Aging Transport Non-Structural Systems Plan will improve the inspection and maintenance of electrical wiring, connectors, wiring harnesses and cables; fuel, hydraulic and pneumatic lines; and electro-mechanical systems such as pumps, sensors and actuators. Collectively, these programs assure good structural, mechanical and electrical condition of aircraft for decades.