History of Flight
On June 18, 2008, at 1001 eastern daylight time, a DeHavilland DHC-6, registration N656WA, operated by Wiggins Airways, was substantially damaged when it impacted terrain during a takeoff attempt from Barnstable Municipal Airport (HYA), Hyannis, Massachusetts. The certificated airline transport pilot was fatally injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight, which was destined for Nantucket Memorial Airport (ACK), Nantucket, Massachusetts. The cargo flight was conducted under 14 CFR Part 135.
The operator reported that the airline was based in Manchester, New Hampshire, while the accident airplane and pilot were based at Hyannis. The flight was scheduled to depart at 0900 but often departed late due to delayed cargo arrival. Around 0800, the pilot contacted the operator by telephone to provide fuel and alternate destination information. At 0956, the pilot contacted air traffic control for taxi clearance and was later cleared for takeoff from runway 24 at 1000.
A witness located just outside the airport perimeter fence near the arrival end of runway 24 observed the airplane taxi. The witness noted that the airplane did not stop and "rev up" its engines as expected, but instead taxied on the taxiway parallel to the runway, then made a 180-degree turn onto the runway without stopping. The airplane initiated a takeoff roll, and the witness noted that the engine sound did not seem to increase. The witness also thought the airplane "must have been empty" because it became airborne within 100 yards of the start of the takeoff roll. As soon as it became airborne, the airplane began a steep left bank. The witness initially thought it was a normal departure, but the low altitude and increasing bank angle led the witness to believe the airplane might "catch a wing" on the ground. The airplane disappeared from view behind trees, and shortly after, the witness heard the sounds of impact.
Meteorological Information
At 0956, the reported weather at HYA included winds from 260 degrees true at 9 knots, visibility 10 statute miles, clear skies, temperature 21°C, dew point 7°C, and an altimeter setting of 29.74 inches of mercury.
Personnel Information
The pilot held an airline transport pilot certificate with a rating for airplane multiengine land, and a commercial pilot certificate for airplane single engine land. According to the operator, the pilot had accumulated 3,607 total flight hours, including 1,927 hours of multiengine experience and 99 hours in the accident airplane make and model.
Aircraft Information
Review of the load manifest revealed the airplane was loaded with 208 pounds of cargo. Examination of recovered cargo confirmed the manifest. Post-accident calculations showed the airplane was within weight and balance limits prescribed by the manufacturer. The DHC-6 Flight Manual includes in the pre-takeoff checklist: "Flight controls - Unlocked - Full travel."
Wreckage and Impact Information
The wreckage was located at 41° 40.31' N, 70° 16.23' W. There was a strong odor of fuel, and all major components were accounted for. The initial impact point was a ground scar about 1,100 feet from the threshold and to the southeast side of runway 24, measuring 14 feet long and 2 feet wide, oriented 165° magnetic. A second ground scar, 5 feet long and 2 feet wide, was about 27 feet beyond. Beyond that was a debris field of forward fuselage and cockpit components. The main wreckage came to rest 53 feet beyond the initial impact point, with the fuselage oriented 350° magnetic. The nose and cockpit area had significant crush damage; the rest of the fuselage aft of the cockpit bulkhead remained largely intact. Both wings were separated at the roots, and the empennage separated just forward of the horizontal stabilizer; all remained attached by control cables. The right wing exhibited leading edge crush damage along the outer third of its span; the left wing along the outer fifth. Control continuity was established from all flight control surfaces to the cockpit. No evidence of corrosion or fatigue failure was observed on any control cables. Both wing flaps were found fully extended, but the drive mechanisms were separated.
The cockpit control column was found in the debris area; the upper flight control lock was still attached to the column by its removable pin, which was tethered by a steel cable. The pins from the two other flight control lock cables were missing, and the cables exhibited overstress failures. The instrument panel-mounted attach tab for the upper control lock was fractured; the portion attaching to the control lock was not located. Red tape, similar to that wrapped around the flight control lock, was deposited on the broken face of the left fuel quantity indicator and lower instrument panel. The lower flight control lock was found inside an unsecured metal tube next to the right seat track. The pilot's four-point restraint was found unfastened with no deformation.
Both engines were dislocated from their mounts; the right engine remained attached by oil lines. One blade from the right propeller was separated at the hub and found about 275 feet beyond the main wreckage, exhibiting severe tip curling and burnishing. All three right propeller blades showed s-bending, chordwise scratching, and leading edge gouging. One left propeller blade had slight forward bending; the other two were bent at about one-quarter span. Internal examination of both engines revealed circumferential rubbing and machining of compressor turbines, shrouds, and other components, but no pre-impact distress or dysfunction.
A Garmin 295 handheld GPS was recovered; examination showed it was not recording track log information at the time of the accident.
Medical and Pathological Information
An autopsy performed by the Commonwealth of Massachusetts, Office of the Chief Medical Examiner, noted the cause of death as "blunt impact." Toxicological testing by the FAA's Bioaeronautical Sciences Research Laboratory detected no traces of carbon monoxide, cyanide, ethanol, or drugs.
Additional Information
A previous DHC-6 accident on March 26, 1973 (NTSB report CHI73AC078) had a probable cause of the pilot's inadequate preflight preparation (failure to remove gust/flight control locks). On July 13, 1979, the manufacturer released service bulletin 6/383 (modification 6/1676, revised March 7, 1980) to modify the flight control locks to minimize the possibility of takeoff with locks installed. Another service bulletin 6/391 (modification 6/1726, issued March 28, 1980, revised September 12, 1980) added a warning flag to the upper portion of the lock to mask essential flight instruments. Both modifications were at operator discretion. A second DHC-6 accident on September 21, 1980 (NTSB report FTW80DA120) had the same probable cause. A third such accident occurred on July 20, 1988 (NTSB report BFO88FA067). On January 31, 1990, superseding service bulletin 6/508 was released, and Transport Canada issued Airworthiness Directive CF-90-01 requiring compliance. The FAA did not issue a similar AD at that time. The flight control lock from the accident airplane had not been modified per any of these service bulletins. After this accident, the FAA issued Airworthiness Directive 2008-CE-046-AD requiring compliance with service bulletin 6/508 within six months of December 30, 2008.