Piaggio P180 N140SL incident near Columbus, Ohio

Probable cause

The failure of water to properly drain through the fuselage drain holes, thus becoming trapped and freezing around the flight control cables, which resulted in the loss of control authority to the airplane's ailerons, elevator, and rudder.

NTSB analysis

During the airplane's descent, the yaw damper disengaged while the autopilot remained on. When the flightcrew checked the flight controls for freedom of control, the ailerons, elevator, and rudder were found to be frozen in place. The flightcrew exerted enough pressure until the controls broke free with a “snap.” The flight controls remained stiff for the remainder of the flight. The temperature was -9 degrees C at the destination. Following a normal approach and landing, the flight controls and nosewheel steering became inoperative. The flightcrew used differential power and braking to taxi to the ramp. A postflight examination by maintenance personnel revealed ice in the area of frame 36 and around the primary flight control cables and pulleys in that area. An examination of the fuselage drain holes showed no obstructions and the airplane was returned to service. An emergency airworthiness directive was subsequently issued that advised of three incidents and that required inspection of the fuselage belly and testing of the fuselage drain holes.

Text from the NTSB. Open the NTSB docket for CEN11IA108 for the full record.