Narrative:

First takeoff since repair of hydraulic leak in right thrust reverser line. Reverser mechanically and hydraulically locked out in accordance with standard procedures as instructed by manufacturer. During takeoff roll at 60 KTS crew alerting system (aural and visual) annunciated 'right. Reverse unlock' warning. Stopped aircraft west/O incident and returned to ramp to visually reconfirm reverser bolted shut. Found reverser still properly secured. Warning determined to be false, caused by removal of hydraulic 'stow' pressure to reverser activator allowing very slight movement to activate 'unlock' microswitch. I consider the current recommended deactivation procedure to be incomplete--should also isolate warning system. Had this false warning occurred at a higher speed and heavier weight the result could have been more serious. Callback conversation with reporter revealed the following: type aircraft given. Aircraft originally certified west/O reversing. Apparently the FAA feels the reporter was operating the aircraft in violation of this restrictions and is investigating the incident further. Reporter advised we would like to contact the FAA reference the MEL and he is in full agreement since he strongly feels the warning system should be deactivated if the reverse system is locked out for any reason. Understands immunity may be affected but does not care. Ironic thing about the incident the aircraft has now been certified to operate with a full reverse system.

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Original NASA ASRS Text

Title: TKOF ABORTED ACCOUNT REVERSE SYSTEM WARNING UNLOCKED.

Narrative: FIRST TKOF SINCE REPAIR OF HYD LEAK IN RIGHT THRUST REVERSER LINE. REVERSER MECHANICALLY AND HYDRAULICALLY LOCKED OUT IN ACCORDANCE WITH STANDARD PROCS AS INSTRUCTED BY MANUFACTURER. DURING TKOF ROLL AT 60 KTS CREW ALERTING SYS (AURAL AND VISUAL) ANNUNCIATED 'R. REVERSE UNLOCK' WARNING. STOPPED ACFT W/O INCIDENT AND RETURNED TO RAMP TO VISUALLY RECONFIRM REVERSER BOLTED SHUT. FOUND REVERSER STILL PROPERLY SECURED. WARNING DETERMINED TO BE FALSE, CAUSED BY REMOVAL OF HYD 'STOW' PRESSURE TO REVERSER ACTIVATOR ALLOWING VERY SLIGHT MOVEMENT TO ACTIVATE 'UNLOCK' MICROSWITCH. I CONSIDER THE CURRENT RECOMMENDED DEACTIVATION PROC TO BE INCOMPLETE--SHOULD ALSO ISOLATE WARNING SYS. HAD THIS FALSE WARNING OCCURRED AT A HIGHER SPD AND HEAVIER WT THE RESULT COULD HAVE BEEN MORE SERIOUS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: TYPE ACFT GIVEN. ACFT ORIGINALLY CERTIFIED W/O REVERSING. APPARENTLY THE FAA FEELS THE RPTR WAS OPERATING THE ACFT IN VIOLATION OF THIS RESTRICTIONS AND IS INVESTIGATING THE INCIDENT FURTHER. RPTR ADVISED WE WOULD LIKE TO CONTACT THE FAA REFERENCE THE MEL AND HE IS IN FULL AGREEMENT SINCE HE STRONGLY FEELS THE WARNING SYS SHOULD BE DEACTIVATED IF THE REVERSE SYS IS LOCKED OUT FOR ANY REASON. UNDERSTANDS IMMUNITY MAY BE AFFECTED BUT DOES NOT CARE. IRONIC THING ABOUT THE INCIDENT THE ACFT HAS NOW BEEN CERTIFIED TO OPERATE WITH A FULL REVERSE SYS.

Data retrieved from NASA's ASRS site as of August 2007 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.