Eurocopter AS 350/355/EC130 - Astar/Twinstar/Ecureuil
Maintenance Powerplant; Maintenance Airframe
Fatigue; Situational Awareness; Time Pressure; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Weather; Human Factors; Airport; Procedure
I work in a 145 Repair station as a hangar mechanic; and I was asked to go to assist in a swashplate change on an AS350B3 that was stuck on the hospital landing pad due to a swashplate shim protruding from the center of the swashplate. The repair took 11 days. We had been working very long hours (10-14hrs daily) in very hot weather all outside on top of the Hospital pad where the helo was stranded. During the swashplate change after disassembly of the main gear box we noticed that the bolt holes had corrosion build up in them and the ring gear had also been corroding due to bad sealant on the bolt heads; so we ended up removing the entire assembly and changed out the epicyclic and housing at the same time. During the reassembly of the housing and epicyclic; (we had been working for 14 hours that day) we decided to call it and to get some rest. I left to go to my hotel and came back in the morning to find that the epicyclic had already been installed into the housing; however; during my RII of the installation I noticed that the gearbox and epicyclic had been coated with Turco instead of mineral oil which is what is called out for. I notified the lead and he said they had installed it after I left. So they came up to the pad to confirm and ended up flushing the system out before we installed the rest of the mast and components. The lead mechanic was instructing and helping to assemble the mast and swashplate assembly (the Maintenance Manual (MM) reference was printed out and we were going step by step). We had to take breaks often due to how hot it would get on top of the hospital but the job got finished.[Several months later] the helicopter was trucked in for a tail rotor strike. During a brief incoming inspection and cleaning another mechanic noticed that the dust cover and or boot that covers the top of the swashplate was missing. During our maintenance ops; there were many people constantly calling to figure out when we would be done which caused many distractions; so less or no phone calls during maintenance ops on an Aircraft on Ground (AOG) aircraft would be immensely helpful. If the aircraft is stuck on the helipad or in an area where it cannot be moved to a hangar; putting up a temp shelter (roof tent) or something like that would help immensely with less fatigue and possible heat stroke; which in turn leads to more mistakes and less work time due to the time spent trying to cool down and regulate body temp and sunburn. No pilot interaction during these maintenance ops would also help a lot; it makes our jobs as mechanics a lot harder when we not only have supervisors and their bosses phoning us all the time to then have the pilot ask how much longer.
This aircraft was removed from service and placed under unscheduled maintenance for removable shims extruding from the swashplate on top of the hospital helipad. A [contract] was submitted for outside help as the maintenance crew on staff had not performed this job to a level of comfort. Maintenance support arrived for assistance. Upon removal of the mast assembly; it was noted that the epicyclic gearbox and sun gear assembly were corroded beyond limits; further increasing the workload on the [roof] of the hospital in the middle of summer; requiring a full transmission replacement. Initially; we were told that removing the aircraft from the hospital by crane was not the best option at the time; as we were only to be performing a couple days' worth of work; but when the corrosion was found; it would have taken the same amount of time to reinstall everything needed to crane the aircraft as to put it back together to return to service. The removal; disassembly; reassembly; and return to service took us 10 days of all mechanics working over 10 hours per day. During this time I worked on and off with the mechanics performing the maintenance; as I am the lead mechanic for the program and had other priorities. During this 10 day event I called a safety stand down day on day 7 as the maintenance crew was showing signs of heavy fatigue; both mentally and physically. The installation; ground runs; and check flights were completed and the aircraft was returned to revenue service. While I was not the primary mechanic on this job; I feel it necessary to submit this as I did help and did not notice the issue. [Over 2 months later] this aircraft was involved in a tail rotor strike at a scene call. This aircraft was loaded on a truck and shipped to a repair station for maintenance required for the tail rotor strike inspection. During acceptance inspection; it was noted that the swashplate appeared to be missing the dust cover on top of the swashplate. I was notified by my supervisor; and began researching this issue. After consulting the removal and installation part numbers; it became apparent that the installed part number was not effective for this aircraft. After consulting the maintenance staff involved; and looking at the Illustrated Parts Catalog (IPC) for this install; we could not find the correct swashplate in the IPC; and the only part number shown was the one that was installed. The repair station has the aircraft at this time; and will make the repairs as necessary. This event was an eye opener to all of us as we look back to all of the long hours that were put in to get this aircraft back in service; and that sometimes we need to take a step back and look at ourselves before we look at the work ahead of us.In my opinion; there were multiple factors that lead to this incident. Maintenance staff was pressured; both personally and by the customer; to provide an expedited service that could not be met. Maintenance pressures were also felt from the heat during this time of the year; on top of an aluminum helipad; with no shade available at the aircraft. The airframe IPC played a large role in the incorrect ordering of parts; as the IPC is somewhat vague when it comes to ordering parts for aircraft with different modifications installed (i.e. dual hydraulics in this case). I believe this incident could have been avoided if the aircraft had been removed from the hospital from the very beginning; removing the pressures from the hospital on a direct level.
Several Maintenance Technicians reported difficult working conditions that resulted in maintenance errors including the possible installation of the incorrect part number.