Narrative:

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/right) 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 (left/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.

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Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.