Accident Overview
On October 25, 2016, about 1415 central daylight time, a Boeing A75N1 (PT17) single-engine vintage biplane, registration N48182, impacted terrain during a takeoff from McCampbell-Porter Airport (TFP), Ingleside, Texas. The airline transport pilot was not injured, and the airplane was substantially damaged. Day visual meteorological conditions prevailed for the personal flight, which had departed Mustang Beach Airport (RAS), Port Aransas, Texas, about 1300 and was operating in the traffic pattern at TFP when the accident occurred.
Aircraft and Operator Information
The airplane was registered to American Airpower Heritage Flying Museum and operated by Commemorative Air Force under Title 14 Code of Federal Regulations Part 91. The aircraft was a single-engine biplane.
Pilot Report and Sequence of Events
The pilot reported practicing takeoffs and landings on runway 13 (5,000 ft by 75 ft, asphalt) with a surface wind slightly left of the runway heading between 5–7 knots. After two uneventful stop-and-go landings, the third takeoff was uneventful until the tail became airborne at about 45 miles per hour (mph), and the airplane began to veer to the right. The pilot responded by reducing right rudder input and applying back stick pressure to become airborne at 65 mph. Upon liftoff, the airplane yawed right as if weathervaning into the wind, despite the wind being left of centerline. The pilot reduced airplane pitch to increase airspeed, but the airplane continued to yaw right and subsequently entered an uncommanded right roll with a slight nose-up pitch attitude. The pilot reported being unable to regain control with full left aileron and left rudder inputs. The airplane impacted terrain off the right side of the runway in a right wing low attitude, with an estimated right bank angle of about 90° when the right wing struck the ground. The airplane nosed over and came to rest inverted, sustaining substantial damage to the upper wing and empennage. The pilot had flown 10 hours in the accident airplane make/model.
Postaccident Examination
A postaccident examination confirmed flight control continuity to all primary flight controls; however, the right horizontal stabilizer and vertical stabilizer were significantly damaged during the accident. The airplane had a braced tail structure, with a bracing wire connecting the horizontal stabilizer forward spar tubes to the vertical stabilizer leading edge. The fractured right horizontal stabilizer's forward and aft spar tubes, right horizontal stabilizer bracing wire with fractured shackle fitting and bolt, and the fractured vertical stabilizer spar tube were sent to the National Transportation Safety Board (NTSB) Materials Laboratory for examination. The laboratory determined that all observed separations were consistent with overstress failure due to impact-related damage; no materials anomalies were identified with any submitted components.
Training Manual Information
The operator provided a copy of their training manual for the Boeing A75N1 (PT17). The manual listed power-off and power-on aerodynamic stall speeds at maximum gross weight as 55 mph and 51 mph, respectively. It stated that after liftoff, a pilot should keep the airplane pitch low to increase airspeed to a recommended climb speed of 75–80 mph for adequate engine cooling and forward visibility. The manual noted that the airplane is known to develop a left swerve during takeoff due to gyroscopic precession, which is proportional to the rate of pitch change during the transition from three-point to tail-up attitude. It stated that if a pilot allows the tail to rise too rapidly, it can result in a rapid left swerve; however, if the tail is raised slowly, a normal right rudder input may result in a right yaw. The right yaw can be corrected by raising the tail more rapidly, using gyroscopic precession to compensate. The manual also cautioned that using aileron when rudder input is recommended during a swerve will result in pilot-induced adverse yaw (an undesirable tendency to yaw opposite to the roll input). It noted that if aileron is applied during a swerve, it should be in the same direction as the swerve. The manual advised pilots to quickly detect small deviations during takeoff and immediately respond with small, precise, and aggressive flight control inputs.
Weather Conditions
At 1415, the TFP automated surface observing system reported: wind 070° at 11 knots, surface visibility 10 miles, clear sky, temperature 31° C, dew point 18° C, and an altimeter setting of 30.10 inches of mercury.