WASHINGTON — The Federal Aviation Administration lacks an adequate system for checking the quality of commercial airplane parts, creating a potential safety risk for airline passengers, according to a new oversight report.

"Neither manufacturers nor FAA inspectors have provided effective oversight of suppliers; this has allowed substandard parts to enter the aviation supply chain," states a 24-page report from the Transportation Department's inspector general.

Federal investigators assessed the oversight of suppliers to the nation's major aircraft manufacturers-Boeing Co., Bombardier Aerospace/Learjet Inc., General Electric Aircraft Engines, Rolls-Royce PLC and Pratt & Whitney and Airbus. They found "widespread deficiencies" at all but one of 21 suppliers that make parts for those companies.

The report found weaknesses throughout the FAA's oversight system for manufacturers and their suppliers. For example, the report blamed four engine failures in 2003 on faulty speed sensors on fuel pumps. The faulty parts were traced to unapproved design changes made by a sub-tier supplier, according to the report.

In another example, a supplier delivered 5,000 landing gear parts for large commercial aircraft that were not made properly. At least one of those gear parts failed while in service, according to the report.

"While the FAA became aware of this in 2003, it has not performed a supplier audit at the facility in the last 4 years," according to the report.

Investigators at another plant witnessed an employee using a piece of paper, scotch-taped to a work surface, to measure an oil and fuel pressure transmitter.

"The aerospace manufacturers and the FAA have put the flying public at unnecessary risk," said Nick Schwellenbach, an investigator at the nonprofit watchdog group Project on Government Oversight, which released the report in advance of the Transportation Department on Friday.

The FAA and the Aerospace Industries Association dispute that the public is in any danger, citing its low-fatality safety record.

The agency plans to implement a new quality assurance program next year to pinpoint potential risks in the supply chain, said Alison Duquette, a spokesperson for the FAA.

The report suggested that part of the reason for a lack of oversight stemmed from companies outsourcing parts to foreign countries. Airline parts that were once only made in America are now built in Asia, Europe and South America.

The report said that the FAA needs to "improve its risk-based oversight system as it does not ensure that manufacturers regularly audit their suppliers."

The FAA has inspected an average of 1 percent of its suppliers used by the manufacturers reviewed by the inspector general, the report found. At the current rate, it would take inspectors nearly 100 years to audit every supplier once.

"We recognize that it is a global industry and there is a trend toward building products globally, so we agree that we need closer scrutiny and we need to find better ways to find potential safety problems," Duquette said.

Michael C. Romanowski, vice president of civil aviation at the Aerospace Industries Association, said the association is reviewing the report to see if there are areas where the industry can improve.

"Manufacturers take their responsibilities for safe products incredibly seriously," Romanowski said. To ensure that manufacturers are delivering safe products, the industry is continuously looking for ways to improve the quality of its products.

"We believe the systems in place provide a high degree of protection of the public and that is reflected in the safety record of the industry," Romanowski said. "Aviation is by far the safest mode of travel and continuing to improve it every day."

Aviation experts say that the lack of oversight of airplane suppliers has been an issue since the early 1990s. It is indicative of a larger problem confronting the aviation industry.

"The whole deterioration of the FAA oversight system is posing a long term risk to aviation safety," said Jim Hall, former chairman of the National Transportation Safety Board. "There are dangerous trends in the aviation industry because we are failing to adequately fund the FAA."

The failure of the federal regulatory system to adjust to the new outsourcing environment is posing a danger to American companies of all stripes, Hall said.

But a defective DVD is a small monetary loss compared to a defective airplane part that could cause a significant loss of life, Hall said.

The airline industry is evaluating the report.

"We are reviewing the inspector general's report and plan further discussions with the FAA and the manufacturers in order to fully understand what steps have been and are being taken to address any concerns," said Victoria Day, managing director of communications for the Air Transport Association, a trade group of airlines.

And the manufacturers are looking for ways to improve oversight of their suppliers .

Peter Conte, a spokesperson at Boeing, said the company takes the inspector general's audit seriously.

"We will work with the appropriate agencies to ensure a full understanding of the report and, if necessary, we will make changes to ensure the highest level of safety for our products," Conte said.

Rebecca Carr is a Washington correspondent for Cox Nedwspapers.