Despite five major plane crashes in the last eight years linked to poor repairs done by outside contractors, the Federal Aviation Administration still does not adequately monitor such work, the Department of Transportation's inspector general said in a report released Thursday.
The use of improper parts and improperly calibrated tools, a reliance on outdated maintenance manuals and poor documentation of the qualifications of mechanics were among the problems found at 18 of 21 contract repair stations reviewed by the inspector general's office, the report said.
"These discrepancies went undetected by FAA surveillance because of the weakness in FAA's oversight structure and the process FAA inspectors used during repair station inspections," the report said.
FAA officials acknowledged Thursday that the contract repair stations, which are required to meet the same standards as the airlines' in-house repair facilities, need closer monitoring.
"We will ensure that we have the resources and methods to further enhance our oversight," said William Schumann, an FAA spokesman. "We have a remarkably safe aviation system, and we want to continue that."
Of 11 major air accidents tied to improper maintenance since 1996, five have been linked to contract work, including the crash of a U.S. Airways Express commuter plane in Charlotte, N.C., in January.
National Transportation Safety Board investigators said that contract mechanics improperly adjusted flight-control cables on the plane two days before the crash, which killed 19 passengers and two crew members.
A combination of malfunctioning controls and excessive weight are considered the most likely causes of the accident.
Overall, the major airlines farm out about 47% of their plane repairs to outside contractors, up from 37% in 1996. Individually, the figures ranged last year from a low of 33% by United Airlines to a high of 79% by Alaska Airlines.
The Department of Transportation said the practice often saves airlines money by reducing the amount of parts, equipment and skilled maintenance personnel they need to keep on hand. But the NTSB has warned since 1997 that the increase in outside contracting necessitates a commensurate increase in FAA surveillance.
Although Thursday's report focused on contract repair stations, the FAA also has been criticized for poor oversight of the airlines' in-house repair facilities.
Deficiencies in the work done by Alaska Airlines mechanics and lax monitoring of that work by FAA inspectors were blamed by the NTSB for the crash of an Alaska jetliner off the coast of Ventura County in January 2000 that killed 88.