Commercial Fixed Wing
Maintenance Avionics
Training / Qualification
Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Environment - Non Weather Related; Equipment / Tooling; Human Factors
I returned to work after a 3 month absence. I am still qualified on the module. I was assigned as the trainer to Mechanic Y. I was training him on the stator case assembly. I demonstrated how to tighten each vane segment foot bolts. The procedure that I was taught; and which had been in use as long as I can remember; was to slide the case and vane assembly; so that approximately one third of it overhung the table surface. Then the bolts were tightened from below with a ratchet with a socket and long extension; repositioning the case and vane assembly as necessary until all bolts were tightened. At the time of the incident; I was not in the work area; having gone to the restroom.Support the case with a hoist and sling before tightening the bolts. This should be added to the job card.
One week after return from 3 months off and being the first time working on this unit as a trainee.On Graveyard shift I was working on the module and order # XXXX. I was tightening the bolts of the vanes. The bolts are tighten from the bottom while the case sits on the table. To access the bolts part of the case is moved slightly beyond the edge of the table. I was sitting in a chair with rollers while I was tightening the bolts. The chair moved; the wrench and its extension did come off the bolt head causing the case to slide off the table and fall to the floor approximately 30 inches.There was no visible damage to the case because it fell directly on my arm and that cushioned the fall. Inspection will be called to inspect the unit.I would add to the job card to support the case with a hoist before tightening the bolts. Or developing a fixture that would allow to reach the bolts from the bottom without having to move part of the case off the edge of the table.
Maintenance Instructor and Trainee reported a training mistake during a training session and both cited being off for an extended time contributed to the event.