A line mechanic reports he forgot to remove a lockout pin from a left engine thrust reverser control...

Narrative:

I had changed the lower thrust reverser 'open' light switch on the left-hand engine. The md-82 aircraft was on placard MEL 78-1; but after changing switch there was no help; the light stayed on in cockpit. So I assumed it would stay on MEL 78-1 and [I] left the pin in the thrust reverser control. After finding out the reverser light staying on in the cockpit; it had to be re-placarded under MEL 78-2. This MEL doesn't require for the thrust reverser control to be pinned (locked-out). [I] did talk to maintenance control to notify change of MEL; which was changed to MEL 78-2. Be advised that weather conditions were cold and raining 45-degrees and steady rain. Also checked reverser was stowed with a logbook entry.two reasons why the event occurred: one; by me assuming that the MEL would stay on 78-1; I didn't bother to unlock the thrust reverser control and after dealing with closing-out the original pilot report and to re-placard it under MEL 78-2; I had forgot to pull the [lockout] pin. Second reason; when having the thrust reverser placarded; I had also assumed that the whole system would be inoperative. On MEL 78-2; the MEL does not state that the crew can still operate [the thrust reverser] system. Suggest [being] more thorough with the MEL procedures and tasks for [reverser] closure. Also; to go back for a second look on my MEL procedures to look for mistakes. I never had this combination of [changing] one MEL 78-1 to 78-2 before. I could assure this will never happen again. Reviewed MEL 78-2 and found my mistake.

Original NASA ASRS Text

Title: A Line Mechanic reports he forgot to remove a lockout pin from a left engine thrust reverser control on a MD-82 aircraft; after he had re-placarded the same engine reverser light under a different MEL.

Narrative: I had changed the lower thrust reverser 'open' light switch on the left-hand engine. The MD-82 aircraft was on placard MEL 78-1; but after changing switch there was no help; the light stayed on in cockpit. So I assumed it would stay on MEL 78-1 and [I] left the pin in the thrust reverser control. After finding out the reverser light staying on in the cockpit; it had to be re-placarded under MEL 78-2. This MEL doesn't require for the thrust reverser control to be pinned (locked-out). [I] did talk to Maintenance Control to notify change of MEL; which was changed to MEL 78-2. Be advised that weather conditions were cold and raining 45-degrees and steady rain. Also checked reverser was stowed with a logbook entry.Two reasons why the event occurred: One; by me assuming that the MEL would stay on 78-1; I didn't bother to unlock the thrust reverser control and after dealing with closing-out the original pilot report and to re-placard it under MEL 78-2; I had forgot to pull the [lockout] pin. Second reason; when having the thrust reverser placarded; I had also assumed that the whole system would be inoperative. On MEL 78-2; the MEL does not state that the crew can still operate [the Thrust Reverser] System. Suggest [being] more thorough with the MEL procedures and tasks for [reverser] closure. Also; to go back for a second look on my MEL procedures to look for mistakes. I never had this combination of [changing] one MEL 78-1 to 78-2 before. I could assure this will never happen again. Reviewed MEL 78-2 and found my mistake.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	985936
Time
Date	201112
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Night
Aircraft 1
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Reverser Lockout
Person 1
Function	Technician
Qualification	Maintenance Airframe Maintenance Powerplant
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy Deviation - Procedural MEL

A line mechanic reports he forgot to remove a lockout pin from a left engine thrust reverser control on a md-82 aircraft; after he had re-placarded the same engine reverser light under a different MEL.