Accident Details
On February 9, 2010, at approximately 1202 Pacific standard time, a Beech 58P, registration N3700N, sustained substantial damage following a nose landing gear collapse during the takeoff roll at Portland International Airport (PDX), Portland, Oregon. The certificated private pilot and his sole passenger were not injured. Visual meteorological conditions prevailed at the time of the accident, and an instrument flight rules (IFR) flight plan was filed. The personal cross-country flight was being conducted under 14 Code of Federal Regulations Part 91. The flight was originating at PDX with a destination of Friedman Memorial Airport (SUN), Hailey, Idaho.
Pilot Statement
In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that during the takeoff roll at about 60 to 70 knots indicated airspeed, the inner tube in the nose gear failed, causing the tire to flatten and skid. The pilot stated that he aborted the takeoff by closing the throttle, and that the skid caused the nose wheel downlock to fail, allowing the nose gear to retract. The pilot added that he used main wheel braking to steer the aircraft to a stop on the grass off the right side of the runway.
Examination Findings
A Federal Aviation Administration (FAA) airworthiness inspector conducted a post-accident examination of the airplane. Damage was observed to the airplane's most forward bulkhead area and surrounding structure, specifically the left and right keels, which had been ground down by more than one-half inch. The examination also revealed that bolt part number 130909B20, which connects the inboard and outboard arms of the nose landing gear retract mechanism, had failed.
According to a Hawker Beechcraft air safety investigator, when the bolt head separated from the bolt shaft, it allowed the inboard arm (part number 002-820016-29) and the outboard arm (part number 002-820016-27) to pivot enough to keep the nose gear retract brace assembly from locking the nose gear in the extended position, thus allowing the nose gear to collapse.
The IIC submitted the failed bolt and the inboard arm to the NTSB Materials Laboratory in Washington, D.C. for further examination. The NTSB metallurgist reported that a visual inspection of the mating fracture surfaces of the bolt indicated that the bolt fractured in the grip region about 0.1 inch from the head in a downward shear due to overstress. The metallurgist also reported that the markings on the head of the accident bolt did not meet the marking requirements of AN3.
Maintenance Records
A review of aircraft maintenance records revealed that during the airplane's most recent annual inspection, conducted on November 20, 2009, the following entry was made: "...Rigged nose gear retract rod for proper down lock tension."