A B1900's trim wheel gear mechanism slipped and caused the trim wheel indication to be 180 degrees off. After take off; an extreme nose up condition required the non flying pilot's trim input to enable the flying pilot to control of the aircraft.
Synopsis
A B1900's trim wheel gear mechanism slipped and caused the trim wheel indication to be 180 degrees off. After take off; an extreme nose up condition required the non flying pilot's trim input to enable the flying pilot to control of the aircraft.
Narrative
First Officer was the flying pilot. Just as I called V1 the First Officer pulled back on the yoke and the aircraft began to climb rapidly. The very second he noticed the climb he began to compensate and push on the yoke. He was pushing so hard he was coming out of his chair. I then asked if he needed help with the trim; he said yes; and I began to roll the trim wheel forward until he said the plane was trimmed. We finished the climb segment; checklist and discussed what had happened. As we reached our cruising altitude he said the trim wheel was binding and the plane felt heavy. I took the controls and evaluated what was happening. He noticed that the trim wheel was so far forward that the trim markers were not visible. The wheel was 180 degrees from where it should be. Being that we had an issue; I contacted Dispatch several times with no luck. Just before I was going to ARINC; the Company flight returning said they would relay for us. I told Company aircraft what we were experiencing and that we will need maintenance upon arrival. Getting closer to our destination I was concerned about what angle the elevator was in and how it was going to affect the landing segment. I declared an emergency with approach. Being that I have flown with this First Officer for several years; I had complete confidence in his ability to finish the flight with him as the flying pilot. I asked the First Officer during the approach to let me know of anything that he feels from the plane that is out of the norm. The First Officer made a near perfect landing. After parking at the gate; airport authority and rescue asked me a few questions about the flight. I was courteous and helpful and thanked everyone very much for their assistance.
Second reporter narrative
I was the flying pilot. As we started the takeoff roll; I noticed that the nose of the aircraft was pitching up. I adjusted the trim wheel forward to compensate.
NASA callback
The reporter stated that this flight was his third flight of the day with this specific aircraft. The First Officer was unable to control the aircraft without the Captain's trim wheel input. When maintenance examined the aircraft after landing; they found that the trim wheel gear mechanism which consisted of three plates compressed together had slipped and caused the trim wheel to be out of sequence by 180 degrees. The malfunction was easily corrected by maintenance. The reporter has never heard of this happening before. The Reporter added that both control columns have electric trim switches but that the manual trim wheel located on the left side of the center pedestal was used to actually trim the Elevator because the First Officer was so busy. The aircraft nose up attitude reached about 40 degrees and the aircraft rolled off on the left wing before it was under control. The trim was set properly at about one and one half units up from zero in the green band which should have yielded about 10 degrees nose up at takeoff.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.