B737-300
Maintenance Airframe; Maintenance Powerplant
Maintenance Inspector 14; Maintenance Lead Technician 10
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural FAR
Procedure; Human Factors; Aircraft; Chart Or Publication
I reviewed and signed-off a Non-Routine [Card] accomplishing Borescope Inspection of Number 1 Engine. Upon review of the attached extended Corrective Action sheet; I noted that all partial work steps had been signed-off by both the Mechanic and Inspector. I reviewed the Corrective Action block on the Non-Routine Card and found the summary of the inspection to be complete and the proper references annotated. At that point I stamped-off the Card. The aircraft was returned to service (not by me) on that evening. The B737 then flew a Non-Revenue flight to ZZZ1; where it was to be staged for flight the next morning. The [Number 1 Engine] Thrust Reverser (T/R) was inoperative (inop) upon landing. I was notified the next day that the Number 1 Thrust Reverser Lockout pin was still installed in the valve which is located in the Left Hand (L/H) Air Conditioning (AC) Bay. The air carrier found our Company's streamer attached to the pin. Someone had closed the AC Bay door without removing the pin or leaving the streamer hanging out. There was no documentation that the TR valves were locked-out; nor that the AC Bay doors were ever opened or closed and therefore I failed to detect that the TR valve was locked out.
Reporter stated he was working as a Contract Maintenance Provider to an air carrier. The Boroscope Inspection on the CFM-56 Engine Compressor and Turbine blade sections found damage that exceeded limitations; requiring the B737 to be ferried to the Operator's Maintenance Base.
A Contract Maintenance Provider was informed about a Number 1 Engine Thrust Reverser (T/R) on a B737-300 that did not deploy on landing; after he had previously reviewed and signed-off a Non-Routine Card for accomplishment of a Borescope Inspection. A lockout pin with streamer attached was found installed in the T/R Control Valve Module.