Accident Overview
On December 6, 2019, about 1315 central standard time, a Beechcraft A36 airplane, registration N408P, sustained substantial damage during an impact with terrain following an aborted takeoff at Kestrel Airpark (1T7), Spring Branch, Texas. The airplane was registered to Aviation Professionals LLC and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 flight. The private pilot and four passengers were uninjured. Visual meteorological conditions prevailed, and a visual flight rules flight plan had been filed for the accident flight to Ennis, Texas (F41).
Pilot Actions and Observations
The pilot had just flown from F41 to 1T7. Prior to departure from F41, he had topped off the fuel tanks, resulting in 80 gallons of fuel for the 1-hour flight; he estimated fuel burn of about 17 gallons. After landing at 1T7, he loaded the 4 passengers and completed an engine run-up with no anomalies noted. He noted that the weight was "more of a load than last time." Due to the crosswind, he elected to use no flaps for the takeoff. At the end of the runway, he held the brakes, applied full power, then released the brakes. He stated the engine sounded normal, but the airplane would not generate lift. When the airplane reached about 80 knots, he tried to rotate, but it would not fly; he felt it "shudder." He then reduced engine power to abort and maneuvered into the grass to slow down, resulting in substantial damage to both wings. The pilot said he thought the airplane reached 4 to 6 ft of altitude.
Weight and Balance Considerations
The pilot stated he was unaware of the density altitude at the time of departure and used 2,100 lbs for the basic empty weight, not thinking the airplane was close to maximum gross weight. The airplane owner provided the most recent weight and balance to the National Transportation Safety Board (NTSB). According to occupant weights from driver's license information, total occupant weight was 765 lbs. The pilot had between 40 and 50 lbs of cargo behind the front seats and 75 lbs in the cargo compartment (aft baggage limit was 70 lbs), plus about 63 gallons of fuel (about 378 lbs). A post-accident weight and balance conducted by the NTSB Investigator-In-Charge (IIC) using provided seating and cargo locations yielded a takeoff weight of about 3,881.34 lbs and a center of gravity of 86.00 inches aft of datum.
The pilot's operating handbook lists a maximum takeoff weight of 3,650 lbs. At that weight, the aft center of gravity limit is 87.7 inches. The handbook does not provide interpolation for weights exceeding the maximum.
Airport and Environmental Conditions
Kestrel Airpark (1T7) is a public airport with runways 30 and 12. The airplane attempted takeoff from runway 30, which is 3,000 ft long and 40 ft wide, sloped 1.4% up. Field elevation is 1,261 ft above mean sea level (MSL). Airport remarks note "Rwy 30 rises rapidly at north end." The closest official weather reporting station at San Antonio Airport (SAT), about 17 miles south, at 809 ft elevation, reported temperature 24°C and dewpoint 6°C. Using SAT altimeter setting of 30.17 combined with 1T7 field elevation, density altitude at the accident time was about 2,091 ft.
Performance Data and Regulatory Information
A review of the manufacturer's flaps-retracted takeoff distance chart in the pilot's operating handbook showed the airplane's weight exceeded the chart's maximum of 3,650 lbs, so takeoff performance could not be determined. The data did not include sloped runway penalties. The FAA publication Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B) notes that increased gross weight results in higher lift-off speed, greater mass to accelerate, and increased retarding force; an upsloping runway impedes acceleration. 14 CFR 91.103 requires pilots to become familiar with available information including runway lengths and takeoff/landing distance data.