The Federal Aviation Administration (FAA) is proposing more maintenance-related penalties against American Airlines.

The FAA plans to fine American $787,500 for three cases of alleged maintenance problems.

In the first case, which occurred in April 2008, the FAA alleges American Air mechanics diagnosed problems with one of two Central Air Data Computers (CADCs) on a McDonnell Douglas MD-82 jetliner. Instead of replacing the computer, mechanics improperly deferred this maintenance under the airline's DC-9 Minimum Equipment List (MEL) by noting that the auto-throttles were inoperative. The MEL, however, does not allow deferral of an inoperative CADC.

The airline subsequently flew the plane on 10 passenger flights before the computer was replaced. During this time, flight crews were led to believe that both computers were working properly. The FAA proposes a civil penalty of $625,000 in this case.

In the second case, the FAA found that in March 2008, American failed to correctly follow an Airworthiness Directive involving the inspection of rudder components on certain Boeing 757 aircraft. As a result, four B-757s operated by American did not comply with the requirements of the AD.

The FAA alleges that after American was advised of the situation, the company said it would cease flying the planes until they were repaired. However, during the following two days, the airline flew two of the planes on a total of three passenger flights. The proposed fine is $75,000 in this case.

Finally, the FAA alleges that in May 2009, American's mechanics returned an MD-82 aircraft to service, even though several steps of a scheduled B-check maintenance visit had not been checked off as completed. The airline also replaced a landing gear door without noting it in the aircraft's logbook.

The aircraft was operated on two passenger flights with the logbook error. An FAA inspection of the aircraft revealed several discrepancies in the tail section, including loose screws, a missing nut plate and a right hand elevator torque tube binding and making noise. As a result of these discrepancies, the FAA plans a civil penalty of $87,500.

American Airlines has 30 days from the receipt of the FAA's latest civil penalty letter to respond to the agency.

The latest fines are in addition to a $2.9 million civil penalty against American Eagle Airlines for operating more than 1,000 flights using airplanes on which improper repairs were performed on landing gear doors.

And it follows disclosure that the aviation agency was fining American Eagle $2.5 million for not making sure crews had accurate information about the weight of baggage on dozens of flights.

A new report by the U.S. Department of Transportation's Inspector General says the FAA has failed to correct maintenance deficiencies at American Airlines.

The report by the DOT watchdog found fault with the FAA's oversight of aircraft maintenance at American Airlines. It said the audit raises questions about the effectiveness of the FAA's maintenance oversight of airlines in general.

OIG recommended several actions to enhance FAA's oversight in key maintenance areas at American--such actions could also improve FAA's maintenance oversight at other air carriers as well as its processes for assessing industry-wide safety allegations.