Maintenance Technicians reported missing a procedural step when deferring a thrust reverser while the aircraft was at the gate prior to departure.
Synopsis
Maintenance Technicians reported missing a procedural step when deferring a thrust reverser while the aircraft was at the gate prior to departure.
Narrative
I was given a gate call tonight on a MAX 8 for a maintenance light. I am a probationary mechanic with helicopter experience and King Air experience. I have no 737 or big jet experience; none the less I went out with confidence in my abilities of reading the manuals and the few months of experience on the aircraft. AMT 2 another probationary mechanic with 4 months of experience on the aircraft came to help me out to the best of his abilities; He also has only 4 months of 737 experience. We arrived at the aircraft and I have personally never worked with the Multi-Functional Display (MFD) but tried to work my way through it. We found that there was a #2 thrust reverser fault. We were first going to troubleshoot the TR (Thrust Reverser) by cycling it and running a bite test. Unfortunately before we got to that we directed by the lead mechanic to defer the #2 TR. So we started looking into the deferral procedure for the #2 TR in which me and AMT 2 have never performed before. We started with adding the inboard TR lock to the #2 ENG then came back up the ramp to read more into the deferral procedure. We had the gate personnel hassling us on how long it will take along with the flight attendant who was very impatient with us. We then added safety wire to the #2 TR to restrict forward movement and then I got on the phone with maintenance control to verify all the procedures were done properly. We then downgraded the aircraft to CAT 1 status and proceeded to fill out the paperwork along with the aircraft log book paperwork. At this point we were approached by the gate attendant who asked 'how much longer'. We proceeded to say we are just doing paperwork and will let you know but then the pilot said 'well if you guys are just doing paperwork we can start boarding so by the time you are done the aircraft would be boarded'. We finished the paperwork and added the correct placarding and sent the aircraft on its way fully confidant for the safety of the passengers and crew. It wasn't till later in the shift that AMT 2 informed me that we never locked out the outboard TR with the lockout bolt. We immediately went to supervision to notify them of the situation. I contribute this to a lack of training on the aircraft. I have never deferred a thrust reverser in my career in aviation and felt thrown to the wolves. We were pressured by the flight crew and the gate personnel. We believed that we performed everything correctly but found a missed step in our deferral.
Second reporter narrative
A fellow coworker received a gate call for a Max 8 for a maintenance light. I decided to go with him and assist on the call. We both are on probation and have four months of 737 experience under our belts. After arriving at the aircraft; we notice there was a fault for the #2 Thrust Reversers. We decided to troubleshoot the T/R (Thrust Reverser) but was soon directed by our lead mechanic to defer the T/R. Neither one of us has encountered this problem before; so we started to look up the procedure for the deferral. First; we started the task by locking out the inboard TR. Next; we went back up to the jetway to continue reading the task. While reading and trying to figure out what to do next we were bombarded by flight attendants' and gate agent's impatiently asking questions on what is wrong; how much longer; why is it taking so long. Trying to handle the situation accordingly and professionally we continued with safety wiring the #2 TR handle to the stowed position. While my Fellow coworker was on the phone with Maintenance Control I was filling out the logbook and trying to see how to downgrade the aircraft to a CAT 1 status. During this process; we were still being asked questions about boarding and how long it would take. Our response was we will let them know. We are working as fast as the matter allows us. Then; the pilot told the gate agent that if they are doing the paperwork they can start boarding now. Thinking that we performed the job correctly we released the plane back to the crew. It wasn't until later when I read the task again to get a better understanding without feeling pressured; rushed or without proper guidance I recall that we did not pin the outboard T/R sleeve. I brought it to my coworker's attention; and we immediately notified our supervisors of our mistake.
More incidents for this aircraft family →
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.