Anchorage, AK, USA
N93V
de Havilland DHC-2
Following a rebuild of the accident airplane, the pilot and the mechanic who rebuilt the airplane conducted a preflight inspection, to include a check of the flight controls, and were satisfied that the airplane appeared airworthy. During the takeoff-initial climb, the airplane was about 150 feet agl at 70 mph airspeed when it suddenly rolled about 90 degrees to the right. The pilot applied left aileron and left rudder control, but the airplane did not respond. He retarded the engine power to idle and pushed forward on the control yoke to maintain airspeed. The airplane's right wing struck the runway and the pilot applied full engine power. The left wing struck the ground, and the airplane landed hard on the main landing gear. The airplane then departed the runway area and collided with a ditch. A postaccident examination of the airplane and flight controls revealed that the chain control linkage, within the control yoke, was misrouted at the base of the control column, thereby reversing the aileron activation. Standard preflight inspection protocols for fixed-wing aircraft require that the pilot ensure that the ailerons deflect in the proper direction when the control yoke is moved to the left and right roll positions.
On April 17, 2007, about 1617 Alaska daylight time, a wheel-equipped de Havilland DHC-2 airplane, N93V, sustained substantial damage when it collided with the runway and a ditch following a loss of control during takeoff-initial climb at the Ted Stevens Anchorage International Airport, Anchorage, Alaska. The airplane was being operated as a visual flight rules (VFR) local area maintenance flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the pilot. The commercial certificated pilot and the sole passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on April 18, the pilot reported that he was departing runway 14. The accident flight was the first flight after the airplane had been rebuilt by a mechanic, who was the passenger. The pilot said both he and mechanic examined the airplane's engine and flight controls before the flight, and both were satisfied that it was ready to fly. After being cleared for takeoff by the Anchorage Air Traffic Control Tower (ATCT) controller, the pilot said he applied full power and lifted off. The airplane was about 150 feet at 70 mph airspeed when the it suddenly rolled about 90 degrees to the right. The pilot applied left aileron and left rudder control, but the airplane did not respond. He retarded the engine power to idle and pushed forward on the control to maintain airspeed. The airplane's right wing struck the runway and the pilot applied full engine power. The left wing struck the ground, and the airplane landed hard on the main landing gear. The airplane then departed the runway area and collided with a ditch. At 1632, a special weather observation at the Anchorage International Airport was reporting, in part: Wind, 150 degrees at 16 knots, gusts to 22 knots; visibility, 10 statute miles; clouds and sky condition, few at 8,000 feet, 11,000 feet scattered, 20,000 feet broken; temperature, 46 degrees F; dew point, 28 degrees F; altimeter, 29.90 inHg. A Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office (FSDO), reported that on April 27, she and another FAA inspector examined the flight control system of the accident airplane, and that of another DHC-2 airplane. The examination revealed that the control system movements of the accident airplane were the opposite of the second airplane. The inspector then removed the entire control yoke mechanism of the accident airplane for a closer inspection. On May 4, the NTSB IIC, and the FAA inspectors examined the accident airplane control yoke in the offices of the FAA FSDO. The examination revealed that the chain control linkage for aileron control, within the pilot's control yoke, was misrouted at the base of the control column, thereby reversing the aileron deflection. With the reversal, when pilot inputs on the control yoke commanded a left roll, the ailerons would roll the airplane to the right, and vice versa for right roll inputs. Standard preflight inspection criteria for all fixed-wing aircraft require the pilot to visually inspect the ailerons for proper deflection when the control yoke is moved to the left and right roll positions.
The improper installation/reversal of the aileron flight control system by other maintenance personnel, and the pilot's inadequate preflight inspection, which resulted in a loss of control during takeoff initial climb.
Source: NTSB Aviation Accident Database
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