Incident Overview
On December 13, 2010, about 0830 eastern standard time, a Piaggio P180, registration N140SL, operated by Avantair Inc., sustained no damage when the airplane’s flight controls bound during approach to Port Columbus International Airport (CMH), near Columbus, Ohio. The two pilots and two passengers were not injured. Marginal visual meteorological conditions prevailed. The flight was operating on an activated instrument flight rules flight plan under 14 Code of Federal Regulations Part 91K. The business flight departed Westchester County Airport (HPN), near White Plains, New York, about 0700, and was destined for CMH.
Flight Details
According to the operator, after departure from HPN, the flight initially leveled off at a pressure altitude of 26,000 feet. An indicated airspeed caution light illuminated, and the flightcrew performed the abnormal checklist for a number two air data computer failure, selecting the number one computer for the remainder of the flight. During descent into CMH at about 15,000 feet, the yaw damper disengaged while the autopilot remained on. The captain instructed the first officer, who was the pilot flying, to check the freedom of the flight controls. The first officer found the ailerons, elevator, and rudder to be "frozen" in place. The flightcrew exerted enough pressure until the controls broke free with a “snap.” The flight controls remained "stiff and sticky" for the remainder of the flight. The flightcrew performed a normal approach and landing on runway 28L. Once on the ground, the flight controls and nose wheel steering became inoperative. The flightcrew used differential power and braking to taxi to the ramp.
Post-Flight Inspection
A post-flight inspection by maintenance personnel revealed ice in the fuselage belly area of frame 36 and around the primary flight control cables and pulleys in that area. The ice was warmed by heaters and removed from the fuselage belly. The fuselage drain holes were inspected for obstructions and general condition; no anomalies were detected. The fuselage belly was towel dried, and the airplane was returned to service. At 0851, the recorded weather at CMH included wind 310 degrees at 8 knots, visibility 4 statute miles, light snow and mist, overcast ceiling at 2,200 feet, temperature -9 degrees Celsius, dew point -12 degrees Celsius, and altimeter 29.73 inches of mercury.
Regulatory Action
On December 20, 2010, the Federal Aviation Administration issued emergency airworthiness directive (AD) 2011-01-53 to all known U.S. owners and operators of Piaggio P180s. The AD stated that the unsafe condition was prompted by three incidents of flight controls jamming on Piaggio Model P-180 airplanes due to water or fluid accumulating and freezing when the aircraft reaches and holds altitudes where the temperature is below freezing. The AD required, before further flight, removal of the central floor panels in the cabin and inspection of the fuselage belly, as well as a functional test of the fuselage drain holes.