Date: 202002
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: 9
Light: Night
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Navigational Equipment and Processing
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Workload; Situational Awareness; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Terrain Warning; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Human Factors; Aircraft
Primary problem: Aircraft

Narrative: During the flight the ADG; Air Driven Generator; erroneously deployed without faults on the electrical system. The noise and vibration could be felt throughout the aircraft. We followed the QRH and reduced airspeed. I landed without difficulty. The company sent Maintenance to the plane and re-stowed the ADG and signed off the logbook. We continued to destination. Enroute we experienced several electrical malfunctions. First a transitory 'AUTO XFER FAIL' caution message appeared. Per QRH no action required. Next both the STAB Trim and Mach Trim caution messages appeared. Per QRH we prepared for a possible out of trim; stabilizer; approach and landing. After about 10 minutes we were able to re-engage both Stab Trim and Mach Trim. The FMS CDU repeatedly displayed 'FMS-FMS N1 Disagree' in the scratchpad. While on radar vectors at 3;000 feet MSL a GPWS 'Too Low Terrain' warning occurred and then ceased. Since we were on radar vectors and between layers with good visibility no action was taken. We were then cleared for the approach with the autopilot engaged. Flight Mode Annunciator captured both the Localizer and Glide slope. Just before the HSI CDI centered; the CDI began moving very rapidly and erratically. I disengaged the autopilot and corrected toward the CDI. There was no reaction by the CDI since they were moving erratically. I elected to go around. Once again on radar vectors we both made comments to each other about the way the instruments behaved. We requested an RNAV approach. We set the RNAV approach in the FMS and prepared for another approach. This time we were past the FAF and descending; above our MDA; when the flight instruments began the same erratic behavior. I again started another missed approach and at the same time received an altitude warning from the Approach Controller. I asked for an airport with VFR weather to make a visual approach. We did not trust our flight instruments.  We diverted to [a suitable airport]. It was this approach where the altitude deviation occurred.  Turning inbound I descended a couple of hundred feet from the 2;100 foot floor. We corrected and landed without further difficulty. On taxi to parking the nose wheel steering failed as I was being marshaled to a stop. The altitude deviation was the result of hurrying to get the plane on the ground. In retrospect; we should have been very deliberate and cautious given the problems we encountered that day; we had plenty of fuel. With the high stress levels we had; CRM would have helped us avoid needless pitfalls.




Synopsis: CRJ-200 Captain reported landing safely after experiencing multiple electrical and autoflight anomalies.