Narrative:

After 7 hours of troubleshooting this aircraft in miserable weather; my co-worker and I consulted with our manager and his manager. It was then decided that we replace the stabilizer trim primary drive motor. We were informed at that time that; conveniently enough; it's in stock here. Anxious to fix the aircraft; we hastily installed the replacement drive motor. The cold weather coupled with a stiff wind of 25-30 mph; and throw in some snow -- made the conditions almost unbearable. We wanted to get done. The PIREP indicated the stabilizer trim would only operate in one direction. We checked operation of the stabilizer trim in both directions ok. It was near the end of our shift; and we wanted to complete the job. In our haste; we failed to notice the part number difference for the stabilizer trim drive motor between the newer md-80 and the legacy part number. In addition; we did not consider the stabilizer trim speed difference during our checkout. Always check for proper effectivity for replacement parts. Always check the tag and part you are installing for proper part numbers and serial numbers. Don't let distractions affect the proper completion of aircraft maintenance tasks. Bad weather played a big role. Time constraints -- toward the end of shift. The different configuration of the new md-80 aircraft having a different stabilizer trim drive motor. Pressure on self to finish job and not let everybody down. Supplemental information from acn 829654: during consultation of troubleshooting; supervisor and manager thought main drive unit was bad. We were at a remote office so they looked up part number; showed we had that part in stock. We then went to the ramp and installed the unit. It was cold; windy and snowing; and we had to work at top of vertical fin. When we did our final paperwork; we didn't notice that the 2 part numbers didn't match. The checkout showed that the stabilizer operated normal up and down. We had the PIREP that the stabilizer would only operate in one direction. We didn't notice at that time that it was running too fast. Double-check part numbers and part lookup for aircraft effectivity. Different aircraft configuration for newer md-80 aircraft part look-up done by supervisor and manager. Cold; windy and snowing hastened the installation of part; toward end of shift missed part number difference on FAA 8130 tag. Callback conversation with reporter acn 830651 revealed the following information: reporter stated his carrier did not have a hangar facility available; so they both ended up staying outside on the ramp; using an open flatbed truck platform while changing the stabilizer primary drive motor; which is located at the top of the vertical fin. The dayshift mechanic's turnover said the stab would not trim 'up;' and suggested a stabilizer trim relay may be the problem; and if that didn't work; than the primary drive may be the answer. Reporter stated he and another mechanic changed the trim relay; which was located just inside the mid cargo door entry sill. The relay change did not correct the problem. He was told three times; the primary drive motor for that md-80 was available. Reporter stated the maintenance manual checkout procedure essentially called for checking the 'pickle' switches and suitcase handles for correct operation. All operations checks were good. The primary drive motor replacement procedures do not call out for a speed check of the stabilizer. But in the stabilizer gearbox change section; which is after the motor drive change section; there is a check for 'time of travel' of the stabilizer. Reporter stated they just did not notice the different part numbers on the FAA 8130 parts tag and should have not been so distracted by the cold weather and end of shift. But he also questions why a different electrical canon plug; or different attach bolts for the primary drive motor; were not designed to help prevent the installation of an incorrect speed ratio drive motor.

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Original NASA ASRS Text

Title: Two Mechanics report on troubleshooting and then changing the horizontal stabilizer primary drive motor at the top of an MD-80 vertical tail; outside; snowing; approximately 15 degrees; with winds of 25 to 30 MPH. Incorrect stabilizer drive installed.

Narrative: After 7 hours of troubleshooting this aircraft in miserable weather; my co-worker and I consulted with our Manager and his Manager. It was then decided that we replace the stabilizer trim primary drive motor. We were informed at that time that; conveniently enough; it's in stock here. Anxious to fix the aircraft; we hastily installed the replacement drive motor. The cold weather coupled with a stiff wind of 25-30 MPH; and throw in some snow -- made the conditions almost unbearable. We wanted to get done. The PIREP indicated the stabilizer trim would only operate in one direction. We checked operation of the stabilizer trim in both directions ok. It was near the end of our shift; and we wanted to complete the job. In our haste; we failed to notice the part number difference for the stabilizer trim drive motor between the newer MD-80 and the legacy part number. In addition; we did not consider the stabilizer trim speed difference during our checkout. Always check for proper effectivity for replacement parts. Always check the tag and part you are installing for proper part numbers and serial numbers. Don't let distractions affect the proper completion of aircraft maintenance tasks. Bad weather played a big role. Time constraints -- toward the end of shift. The different configuration of the new MD-80 aircraft having a different stabilizer trim drive motor. Pressure on self to finish job and not let everybody down. Supplemental information from ACN 829654: During consultation of troubleshooting; Supervisor and Manager thought main drive unit was bad. We were at a remote office so they looked up part number; showed we had that part in stock. We then went to the ramp and installed the unit. It was cold; windy and snowing; and we had to work at top of vertical fin. When we did our final paperwork; we didn't notice that the 2 part numbers didn't match. The checkout showed that the stabilizer operated normal up and down. We had the PIREP that the stabilizer would only operate in one direction. We didn't notice at that time that it was running too fast. Double-check part numbers and part lookup for aircraft effectivity. Different aircraft configuration for newer MD-80 aircraft part look-up done by Supervisor and Manager. Cold; windy and snowing hastened the installation of part; toward end of shift missed part number difference on FAA 8130 tag. Callback conversation with Reporter ACN 830651 revealed the following information: Reporter stated his carrier did not have a hangar facility available; so they both ended up staying outside on the ramp; using an open flatbed truck platform while changing the stabilizer primary drive motor; which is located at the top of the vertical fin. The dayshift Mechanic's turnover said the stab would not trim 'up;' and suggested a stabilizer trim relay may be the problem; and if that didn't work; than the primary drive may be the answer. Reporter stated he and another Mechanic changed the trim relay; which was located just inside the mid cargo door entry sill. The relay change did not correct the problem. He was told three times; the primary drive motor for that MD-80 was available. Reporter stated the Maintenance Manual checkout procedure essentially called for checking the 'pickle' switches and suitcase handles for correct operation. All operations checks were good. The primary drive motor replacement procedures do not call out for a speed check of the stabilizer. But in the stabilizer gearbox change section; which is after the motor drive change section; there is a check for 'time of travel' of the stabilizer. Reporter stated they just did not notice the different part numbers on the FAA 8130 parts tag and should have not been so distracted by the cold weather and end of shift. But he also questions why a different electrical canon plug; or different attach bolts for the primary drive motor; were not designed to help prevent the installation of an incorrect speed ratio drive motor.

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.