Narrative:

Due to a lengthy maintenance delay at the previous airport; our assigned aircraft arrived several hours late (revenue flight). We were scheduled to position the airplane and accepted the inbound aircraft from another crew. We talked with the inbound crew who told us about the previous discrepancy which was a faulty stabilizer trim switch on the copilot's yoke. Our maintenance at the previous airport had removed and replaced the first officer's yoke-mounted trim switch. During preflight for our flight I asked the first officer to set the stab trim. The first officer immediately noticed that the stabilizer trim was moving in the opposite direction that he selected. We confirmed this was indeed the case and made a logbook entry. Apparently; the previous crew had not noticed the anomaly probably due to the fact that it was the captain's leg. The flight director and VNAV window were set up this way when we accepted the aircraft. The flight was eventually canceled and rescheduled the next day. Checking the maintenance log the next morning; it appeared that outstation maintenance that night had to 'rewire' the yoke trim switch which indicated to us that in fact; the maintenance personnel at the previous station had wired the switch inside the yoke with reversed polarity and/or had not made a proper operational check of the trim system prior to signing it off. There was also paperwork error indicating the trim switch had been deferred that day which it had not been as far as we could tell. Fortunately this error was caught at the gate. I believe that this issue could have become an emergency situation very quickly after in-flight actuation.

Related reports:

Google
 

Original NASA ASRS Text

Title: A CRJ200 First Officer's faulty horizontal stabilizer yoke trim switch was replaced the previous flight but installed upside down so that up trim actuated a down stabilizer movement.

Narrative: Due to a lengthy maintenance delay at the previous airport; our assigned aircraft arrived several hours late (revenue flight). We were scheduled to position the airplane and accepted the inbound aircraft from another crew. We talked with the inbound crew who told us about the previous discrepancy which was a faulty stabilizer trim switch on the copilot's yoke. Our Maintenance at the previous airport had removed and replaced the First Officer's yoke-mounted trim switch. During preflight for our flight I asked the First Officer to set the stab trim. The First Officer immediately noticed that the stabilizer trim was moving in the opposite direction that he selected. We confirmed this was indeed the case and made a logbook entry. Apparently; the previous crew had not noticed the anomaly probably due to the fact that it was the Captain's leg. The flight director and VNAV window were set up this way when we accepted the aircraft. The flight was eventually canceled and rescheduled the next day. Checking the maintenance log the next morning; it appeared that outstation maintenance that night had to 'rewire' the yoke trim switch which indicated to us that in fact; the maintenance personnel at the previous station had wired the switch inside the yoke with reversed polarity and/or had not made a proper operational check of the trim system prior to signing it off. There was also paperwork error indicating the trim switch had been deferred that day which it had not been as far as we could tell. Fortunately this error was caught at the gate. I believe that this issue could have become an emergency situation very quickly after in-flight actuation.

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.