Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Confusion; Situational Awareness; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Incorrect / Not Installed / Unavailable Part
Number One engine outboard side mount was written up for failed Drift Check.  Mechanic changed mount bracket and attaching hardware only.  Other side mount assembly components were not taken out of the box and changed as required.  The task was accomplished during Routine Overnight Maintenance (RON) and completed on the next shift.  Incoming Lead Mechanic put supposedly all removed engine side mount components on Supervisor's Review cart after asking outgoing Lead Mechanic if those were the old parts which he confirmed.   It was determined that [some] parts were not changed out as required when one Supervisor reviewed parts for turn-in/ repair.  Note: Another Supervisor previously signed turn-in rotable for old parts that still had the new parts in the box. The Task of changing the engine mount was written up as a discrepancy as part of a scheduled engine removal and re-install on a weekend aircraft project. Maintenance Control was notified and Chief Inspector was consulted for any and all actions to be taken at the time of discovery. [Recommend] all Maintenance personnel should be reminded that any parts replaced on an aircraft requires complete removal of assembly and turned in as a complete assembly at the time the maintenance action has started.  Maintenance personnel should ensure that any sign-offs for removal and replacement of assembled components are actually complied with (example all new parts taken out of box and old ones immediately turned in). [Improper Maintenance noticed] after aircraft dispatched.
After realizing that a #1 Engine mount change was only partially completed on a DHC-8-100 aircraft that had already departed; an Aircraft Maintenance Technician (AMT) recommends that all Maintenance personnel should ensure that any sign-offs for removal and replacement of assembled components are actually complied with.