Narrative:

I was assigned a routine operation to replace the left overwing escape slide. All amms were available and used while maintenance was being performed. We disarmed the system and replaced the left slide as per the amm without any problems. The system was being rearmed per the amm; when the step was reached to reconnect the battery packs; the right overwing slide deployed. The amm states that both left and right battery packs must be disconnected when working on either side. After the fact; while researching the amm to learn what could have happened; it was found that the overwing door switches did not need to be placed in the safe position on the opposite side; only the side being worked. The only step that involves both sides of the aircraft is the battery packs. We had moved both side escape door switches to the safe position. Further investigation by the next shift revealed those switches appeared to be sticking and not returning to the correct position. It is believed that this caused the slide to deploy when the batteries were reconnected. Clearer amm instructions as to which part or parts of the system need deactivation when performing certain tasks would be helpful to prevent a possible recurrence.

Google
 

Original NASA ASRS Text

Title: After the left overwing slide was replaced; a mechanic reports the right overwing slide on a B767-300 deployed during the rearming procedure.

Narrative: I was assigned a routine operation to replace the left overwing escape slide. All AMMs were available and used while maintenance was being performed. We disarmed the system and replaced the left slide as per the AMM without any problems. The system was being rearmed per the AMM; when the step was reached to reconnect the battery packs; the right overwing slide deployed. The AMM states that both left and right battery packs must be disconnected when working on either side. After the fact; while researching the AMM to learn what could have happened; it was found that the overwing door switches did not need to be placed in the safe position on the opposite side; only the side being worked. The only step that involves both sides of the aircraft is the battery packs. We had moved both side escape door switches to the safe position. Further investigation by the next shift revealed those switches appeared to be sticking and not returning to the correct position. It is believed that this caused the slide to deploy when the batteries were reconnected. Clearer AMM instructions as to which part or parts of the system need deactivation when performing certain tasks would be helpful to prevent a possible recurrence.

Data retrieved from NASA's ASRS site as of May 2009 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.