B737-900
Maintenance Airframe; Maintenance Powerplant
Communication Breakdown; Situational Awareness; Time Pressure
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors; Company Policy; Procedure
Aircraft supervisor approached me in my office and said he needed the inspector slot on log page for the #1 engine change signed for. I asked him if all the paper work was complete and the job was complete and his reply was yes and that the aircraft was at the terminal being loaded for its [next] trip. After I signed the log book I went to review the engine change paper work package when I discovered the Engine change installation task was not completed. By the time this discovery took place the aircraft already [departed].
A Maintenance Inspector discovered that the Maintenance Supervisor was incorrect when he reported that all of the engine change paperwork was completed when he requested the final signoff.