History of Flight
On February 23, 2017, about 1300 mountain standard time, a Beechcraft A36TC airplane, registration N3803J, was substantially damaged when it impacted terrain shortly after takeoff from Stevensville Airport (32S), Stevensville, Montana. The private pilot and his passenger received minor injuries. The airplane was registered to Big Sky Specialized Carriers and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed and no flight plan was filed. The cross-country flight was originating at the time of the accident.
According to the pilot, he based the airplane at 32S. The takeoff was conducted from runway 12. Before takeoff, the pilot noted that the windsock indicated a straight cross wind with gusts from both directions. The pilot confirmed manifold pressure and fuel consumption as he held the brakes, then accelerated the airplane to 80 knots and lifted off. Shortly after, the airplane could not climb or accelerate. The pilot stated he was unaware of the cause and felt a rapid decrease in power. He ensured engine controls were set for full takeoff power but the airplane would not lift further. He had insufficient time to scan engine instruments or diagnose the problem due to low altitude. The pilot did not retract the landing gear. He did not report maximum altitude but noted previous problems with the turbocharger system.
Ground scars indicated the airplane struck terrain about 300 ft to the right of runway centerline and traveled a few hundred feet after initial contact. The airplane came to rest upright.
A pilot-rated eyewitness situated on the northeast side of the runway, about 2,400 ft from the runway 12 threshold, reported his attention was drawn by the engine sound, which he described as normal, strong, loud, and ear piercing. The airplane broke ground as it passed abeam him; he commented to a companion that the takeoff appeared unusual. The airplane achieved a maximum altitude of about 50 ft, then began a steep right descending turn. The right wingtip struck the ground first, exhibiting a brief flash of fire that quickly extinguished. The witness noted runway 12 has a substantial uphill slope, and the terrain and trees rise in that direction. He reported a quartering tailwind from the northwest of about 15 knots.
Personnel Information
The pilot held a private pilot certificate with a single-engine airplane land rating, issued June 2015. According to information provided, he had 569 total flight hours, including about 162 hours in the accident airplane make and model. His most recent FAA third-class medical certificate was issued in April 2015.
Aircraft Information
The single-engine airplane was manufactured in 1980 and equipped with a Continental TSIO-520 series engine. The pilot purchased it in February 2016.
The airplane was equipped with Genesis Aero wingtip fuel tanks via Supplemental Type Certificate (STC) SA2460CH, installed June 2008, enabling 40 gallons additional fuel. The STC increased maximum takeoff weight from 3,650 lbs to 3,833 lbs.
Maintenance records showed the most recent annual inspection completed September 24, 2016, with tachometer time 2,859.0 hours. The most recent airframe entry dated February 1, 2017, indicated tachometer time 2,920.9 hours. The engine was major overhauled in August 2010 at 2,282.1 hours. During the September 2016 annual, all six cylinders were replaced with new Continental Loaded Cylinders. The most recent engine logbook entry, for an oil change dated February 17, 2017, cited airframe TT 2,920.9 hours and time since major overhaul 633.7 hours. The propeller, a Hartzell Model PHC-C3YF-1RF, was overhauled in September 2005 at 1,877.8 hours; the governor was overhauled with the 2010 engine overhaul. At the accident, tachometer registered about 2,927 hours.
Meteorological Information
The airport's windsock was about 400 ft northeast of runway centerline and 1,500 ft along the runway 12 axis, about 100 ft west-southwest of a hangar, mounted on a 20 ft pole. An automated weather observation system (AWOS) was installed in November 2016, broadcasting on the CTAF frequency. The wind sensor was near the approach end of runway 12, about 300 ft northeast of centerline and 100 ft along the runway axis, mounted on a 10 ft mast on flat, open terrain.
AWOS data from 1256 to 1303 recorded wind from 340° and 350° magnetic between 9 and 12 knots, with gusts to 16 knots; averaged 347° at 11 knots, gusts 16 knots. Visibility 10 miles, temperature 2°C, dew point -6°C, altimeter 29.98 in Hg. Computed values for runway 12 departure: steady state tailwind component 8.5 knots, gust tailwind 11.2 knots; station pressure 26.27 in Hg; pressure altitude 3,556 ft; density altitude 2,914 ft.
Airport Information
Runway 12 has a substantial uphill slope. The airport elevation and runway details are consistent with the performance calculations.
Wreckage and Impact Information
The engine mount was partially separated from the firewall; the cowling and propeller were significantly damaged. The fuselage exhibited crush, twist, and wrinkling deformation but retained cabin occupiable volume. Wings and tail surfaces remained attached. Flaps were fully retracted. Both wingtip fuel tanks were fractured; left wing leading edge incurred crush damage. Nose and left main landing gear were completely fracture-separated; right main landing gear partially separated. No fire. Front seats remained attached; occupant restraint belts intact. The aft club-seating cabin was reported full of luggage and cargo by first responders. Personal effects and baggage were recovered and weighed.
A Garmin GPSMap 396 device was present but did not capture the accident flight. Examination of the engine revealed no abnormalities that would have precluded normal operation and power production.
Additional Information
The Pilot's Operating Handbook (POH) stated maximum takeoff weight (MTOW) as 3,650 lbs. A supplement for the wingtip fuel tank STC indicated MTOW increased to 3,833 lbs. The most recent weight and balance record (June 14, 2008) incorporated the tip tank installation, showing empty weight 2,724.38 lbs and empty CG 81.44 inches.
All cargo except two items was weighed after the accident. Based on known weights for cargo, pilot, passenger, fuel, and other items, plus an estimated 68 lbs for the two unweighed items, the calculated airplane weight was 4,053 lbs—about 220 lbs above the STC maximum and about 400 lbs above the original MTOW. CG calculations, assuming cargo CG at the approximate midpoint of the seating and cargo area, resulted in a loaded CG of 85.5 inches. Investigation-created extrapolations of CG boundaries to the calculated weight indicated the CG would be within those boundaries toward the forward limit, but such extrapolations are not authorized.
The pilot's written report stated the airplane maximum gross weight as 3,600 lbs and takeoff weight as 2,800 lbs. The reasons for discrepancies with actual values were not determined.
Takeoff performance data from the POH, based on conditions including 3,650 lbs, level runway, and 8.5 knot tailwind, gave ground roll 1,650 ft and 50 ft obstacle distance 2,800 ft. With a 10 knot tailwind, ground roll 1,900 ft and obstacle distance 3,050 ft. The tip tank STC specified increasing the 3,650 lb takeoff distances by 11%. Thus, at 3,833 lbs and 8.5 knot tailwind, ground roll would be 1,831 ft and obstacle distance 3,108 ft; at 10 knot tailwind, ground roll 2,109 ft and obstacle distance 3,385 ft. Neither the POH nor the STC supplement provided performance data for the overweight condition (220 lbs excess), the uphill runway slope (1.94%), or the actual tailwind component (11.2 knots), all of which would increase distances.
The FAA Airplane Flying Handbook notes that ground effect reduces induced drag, allowing an airplane to become airborne at insufficient airspeed, but climb performance may be marginal as it leaves ground effect.