PA-46 Malibu Meridian
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 65; Flight Crew Total 1200; Flight Crew Type 65
Aircraft Equipment Problem Critical; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Taxiway; Inflight Event / Encounter Weather / Turbulence
General Maintenance Action
Aircraft; Human Factors
On ground Controller warned of incoming storm from the south. I suggested that I remain in pattern and just do some full stop landings ahead of the storm. Controller said storm was not moving quickly and likely could get in at least one practice instrument approach. Controller said Approach was busy that day so I said I would vector myself. Flew ILS XX approach. Vectored self successfully and joined the localizer. Encountered light rain at ZZZZZ [fix] but maintained VFR. Inside of ZZZZZ rain stopped. Cleared for landing on Runway XX and had very nice; smooth landing. Use Beta to slow aircraft down and left runway for taxiway without incident. Controller advised re: taxiways back to hangar. Left turn off of runway then right turn onto Taxiway 1. At end of Taxiway 1 left turn at Taxiway 2/3 intersection. Plane facing west. Braked; trying to stop at the intersection to confirm controller instructions. Plane would not stop and would not go straight. Very unusual and had not encountered that situation before. Plane veered off taxiway to left; went off into grass and down a slight hill; doing a 180; facing east. Then came to a full stop. No plane damage and no injuries. Passenger who had much difficulty fitting into the passenger seat. He was a big man and was quite cramped. He asked if seat would go back further but it would not. Not sure if his feet interfered with brakes/rudder pedals. Personnel showed up and provided tow vehicle. Had plane towed back to hangar. Aircraft to be inspected.
PA-46 pilot reported that the aircraft would not stop or go straight while approaching a taxiway intersection; then departed the taxiway and finally stopped. Pilot suggested that the passenger's feet had interfered with the brakes and rudder pedals.