Date: 201511
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Weather elements / visibility: Fog; 2
Light: Daylight
Aircraft: PA-32 Cherokee Six/Lance/Saratoga/6X
Operator: FBO
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Final Approach
Airspace: Class D ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Autopilot
Component problem: Malfunctioning
Reporter organization: FBO
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter CFTT / CFIT; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Automation Aircraft Terrain Warning; Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: I had taken a passenger (also a pilot) on a flight. We turned around due to fog not lifting at the destination.There were equipment issues in the rental aircraft; a T-Tail Piper PA32 Lance. The first thing noticed was that the intercom didn't work. I could talk to the passenger but he couldn't talk to me.The #2 radio would not transmit when selected and the #1 unit was scratchy and often not clear on reception.There was no panel mounted GPS database at all so I used my portable Garmin 496 for navigation.The landing gear unsafe light was on all the time; but went out when the gear came down. There was a standby vacuum warning light on and off but the vacuum pump gauge showed no malfunction. The amp gauge had no pointer; but for voltage check; the 496 portable GPS has a voltage indication; which was fine.Other things seemed to work OK; but I made the mistake of trusting the autopilot too much.Upon commencing the ILS approach to Runway XY; I had all the parameters set up correctly on the radios; HSI; and #2 CDI. When selecting the LOC function on the autopilot the airplane flew into an unusual attitude and the GPS terrain warning came on. The airplane rolled into a steep bank and the nose dropped.ATC was talking to me; telling of the warning. I told them I would abandon the approach but mostly I was busy disconnecting the autopilot; correcting the wings to level and initiating a climb.The approach controller talked too much while I had things to do to straighten out the aircraft; but I'm sure that's their function. I tried to ignore audio in my headset until the aircraft was in a normal attitude.Eventually I said to them; I have the wings level; I'm climbing and proceeding to the 180 degrees heading you assigned me.I hand flew the second approach.First I told the tower I wanted to land straight in on Runway XY because I didn't want to circle due to the high accident rate of circling approaches. But when I descended out of the clouds; I saw I was traveling too fast; so told the tower I wanted to land on the other end; Runway XX; due to the strong winds.After circling the field; the landing was uneventful. Upon returning the plane to the FBO; I told maintenance of the issues reported here.




Synopsis: PA32 pilot reported a malfunctioning autopilot put the aircraft into an unusual attitude and triggered a terrain warning on approach.