American Airlines earlier this month temporarily grounded 22 of its Boeing MD-80s – returning the final aircraft to revenue service last weekend - after finding paint chips in the fuel filters of the aircraft, Flight can exclusively reveal.
The problem was first spotted during the week of November 6 when filter warning lights illuminated on two MD-80s, an American spokesman tells Flight.
Maintenance workers determined that the aircraft were part of a batch of 32 that had been through a major overhaul in the summer months, during which their fuel access plates – manufactured by the carrier in Tulsa, Oklahoma - were painted.
Inspections determined that 22 of the 32 aircraft had paint chips in the fuel filters.
“We discovered that the paint we put on plates did not adhere,” says the American spokesman, adding that the paint was “coming off in little flakes”, which were being found in the fuel filters.
He says the MD-80 fuel filters “never had a full clog” nor caused an in-flight engine shutdown and the paint chips were “never a safety issue as far as we’re concerned”.
However, the carrier did pull the 22 aircraft out of service to repair the problem at its airport line maintenance facilities and overhaul bases, causing some service cancellations. At the peak of the groundings, some 40 flight segments were cancelled, but that figure was quickly reduced as aircraft returned to service, says the spokesman.
A new procedure that involves changing the way the plates are prepared for paint was employed by maintenance staff for the 22 aircraft, and will be used in the future by the carrier.
“We have found a good solid fix,” says the spokesman, noting that the airline now has “a different way of getting the paint to stick”.
By the middle of last week, only six aircraft remained out of service. These final airliners were returned to service over the weekend.
The financial impact of fixing the problem – and the subsequent cancellations – has not yet been calculated by American. “The additional maintenance cost of doing this in a hurry probably has some impact,” says the spokesman.
American will continue to monitor the filters and the plates, he says.
While flakes were not found on the remaining 10 of 32 MD-80s involved in the summer maintenance overhaul, the spokesman says: “I am quite certain that those aircraft will be redone as well, routinely, even though they haven’t generated any flaking captured in the filter.”