Two Line Mechanics report not locking out (deactivating) the # 3 engine thrust reversers and not downgrading the MD-11 aircraft's Category (Cat) Status. Supervisor pressure to depart aircraft and a lack of clarity in the CDL procedure were cited as reasons the MEL Maintenance procedures were not accomplished.
Synopsis
Two Line Mechanics report not locking out (deactivating) the # 3 engine thrust reversers and not downgrading the MD-11 aircraft's Category (Cat) Status. Supervisor pressure to depart aircraft and a lack of clarity in the CDL procedure were cited as reasons the MEL Maintenance procedures were not accomplished.
Narrative
Aircraft was assigned to me and my partner (Mechanic 'X'); along with two other aircraft for that night. When we received the MD-11 aircraft; I found the #3 engine thrust reverser (TR) blocker door damaged. After Walk-around and doing an Inspection; I called Maintenance Control and asked for a deferral on the #3 engine blocker door. Maintenance Control said 'yes'; you can defer it; per CDL. The other aircraft that we were assigned; were due out at the same time as I was working on the blocker door. I dispatched the other aircraft leaving MD-11 on a late departure. While I was finishing up removing blocker door; Mr. 'X' called Maintenance Control upstairs on the aircraft for a deferral on the #3 engine blocker door. When he came down from the aircraft after he deferred it; we dispatched the aircraft. We did not downgrade and lock out the TR for the #3 engine. We feel because the CDL was unclear; we did not lock out reverser and downgrade the aircraft. It will not happen again; we know where we went wrong.
Second reporter narrative
My partner; Mechanic 'Y'; and I performed a service check on an MD-11 aircraft. Upon doing the walk-around inspection; Mechanic 'Y' found a blocker door on the #3 engine to be damaged. He then notified our Supervisor and contacted Maintenance Control. We were told that we could CDL the blocker door; but it was required to be removed. So we removed the Blocker door from the #3 engine. While Mechanic 'Y' was finishing up the blocker door; I then went up to the cockpit to finish the Logbook for the removal of the blocker door and the installation of the CDL placard. During the same time; we also had two other aircraft to perform Inspections and depart. When talking to Maintenance Control; we were not given any directions that when the blocker door is placed on CDL; you also have to deactivate the thrust reverser and then downgrade the aircraft CAT status. The aircraft left about an hour late. We were pressured by our Supervisor to complete the aircraft as soon as possible. I feel the problem that occurred was that of trying to depart the aircraft quickly and that I did not verify the CDL for the exact procedures of what if anything; had to be completed. Also the CDL was very confusing to me; due to the CDL did not state very clearly that a MEL was also required. Now in reviewing this procedure I now know that I will not miss this very important step again.
NASA callback
Reporter stated that neither one of them had done a deferral procedure for a damaged blocker door before. The Maintenance Controller also never informed them that an MEL procedure was required. The #3 engine outboard reverser had the damaged blocker door. Reporter stated the CDL requires the Blocker door be removed; but other Mechanics have noted the Reverser was considered usable and not Locked-out per MEL procedures. To accomplish removal of the blocker door per the CDL and deferral per the MEL; Mechanics have to use three different Manuals; the CDL; MEL and the Aircraft Maintenance Manual (AMM). Reporter stated why bother removing the blocker door if the reverser also needs to be locked out?
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.