Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Confusion; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors; Procedure
Engine S/N XXXX-48 on a DHC-8-100 aircraft had an overtorque.  Engine was changed; as instructed by my Lead Mechanic; who was instructed by Engine Program Manager.  We removed Reduction Gearbox RGB 120306 from Engine XXXX-48 and sent it out for inspection.  We then installed Reduction Gearbox RGB (YYYY-24) on Engine XXXX-48. Engine was signed-in February; 2014. Don't know when engine was installed; but when [mistake was] discovered ten days later; the aircraft came to ZZZ to change engine. Overtorque was 168.3%.  My Lead and myself checked manual and found that the overtorque was [actually] 'Out of Limits'; but that was after Program Manager came to Shop on that day. Neither one of us ever checked the manual; just took Manager's word that turbo machine [Engine] S/N XXXX-48 was serviceable.  Engine Program Manager came to Shop and asked about the engine; he wanted to send engine out. Lead Mechanic told Program Manager [that] engine is [already] on aircraft. Lack of communication between Engine Program Manager and Lead Mechanic.  I knew it was [originally] an overtorque; but never asked how much. My Lead showed me the paper ten days [after the RGB change] that showed [an overtorque] at 168.3%.  If I would have [previously] asked how much [overtorque]; a light would go off; that's a lot; lets check manual.  The engine was changed at ZZZ.  Myself and my Lead should not take anyone's word that an overtorqued engine is serviceable; we both need to check the manual before; not after the fact.
An Aircraft Maintenance Technician (AMT) describes how a lack of communication between his Lead Mechanic and their Engine Program Manager contributed to their replacing a Reduction Gearbox (RGB) on a PW 120 engine that had overtorqued; instead of removing the engine from a DHC-8-100 aircraft.