Regional Jet 200 ER/LR (CRJ200)
Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; General Declared Emergency
Aircraft; Human Factors
Still in cruise just before descent we received both a STAB TRIM and MACH TRIM caution message. We complied with the QRH but the system would not reengage. As we started our descent we also began getting AP TRIM (NU and ND) caution messages. At this point I told the First Officer to tell ATC we would not be able to maintain the increased speed they wanted and we would do 250 KIAS. I also had the First Officer declare an emergency with them due to the uncertainty about how badly out of trim the aircraft was going to be when the autopilot was disengaged and as we went through configuration changes. We ran all our data for a flaps 20 landing per the QRH. As we began to slow for the downwind the autopilot was having real trouble maintaining altitude and began a descent and showed no signs of stopping. I disconnected the autopilot and flew the rest of the way manually. The aircraft required significant pulling forces to counteract the nose down tendency. As we added the flaps the pressure was less but still significant. The landing was safe and uneventful followed by a normal taxi in.
Just prior to descent; CRJ200 Captain experiences a STAB TRIM and MACH TRIM caution message. QRH procedures are complied with without success. An emergency is declared and the descent and downwind is flown with the autopilot engaged until it will not maintain altitude. The approach and landing are flown with significant back pressure required to a normal landing.