NTSB Factual Report

On March 31, 2001 at 1215 central standard time, a DeHavilland DHC-3, single-engine airplane, N120BA, struck trees and terrain following a loss of control during the takeoff/initial climb from the north runway at the private Bishop Airfield near Decatur, Texas. The airplane was owned and operated by Bishop Aviation, Inc., of Decatur, Texas, under 14 Code of Federal Regulations Part 91. The airplane transport pilot and 4 passengers received serious injuries, 13 passengers received minor injuries, and 4 passengers were not injured. The airplane sustained substantial damage. Visual meteorological conditions prevailed for the sky diving flight, and a flight plan was not filed for the local flight.

According to local authorities and the FAA inspectors, who responded to the site, the airplane was carrying parachutists for a local sky-diving jump from 13,000 feet msl. The pilot reported that most of the jumpers were experienced instructors from the Skydive Texas Facility at Bishop Airfield.

The FAA inspectors, after interviewing the passengers, reported a total of 22 persons (1 pilot-in-command, 17 experienced jumpers, and 4 tandem jumpers) on board the aircraft at the time of the accident. One passenger told an FAA inspector that on "takeoff roll, the engine seemed to produce enough power." Further, he stated that the tail would normally rise first, but this time the aircraft assumed a "very steep angle of attack." He saw the pilot "winding the wheel on the lower right side of the chair clockwise, frantically." The pilot pushed forward and left on the control yoke. The tail of the airplane hit the ground. Another passenger told an FAA inspector that about 4-5 seconds after takeoff, the airplane "made a hard right and the pilot was busy with a wheel between the seats."

The FAA inspectors interviewed two witnesses at the airport. One witness stated "the airplane got up [and] made a sharp turn to the right." Subsequently, the "wing went perpendicular to the ground, tried to pull up and took a diagonal nose dive and hit the ground." The other witness observed the airplane climb to "about 300-500 feet with the nose of the plane pointed up." Subsequently, the airplane took a "90 degree turn to the right as the wing dipped down. The plane then seemed to level off and then headed in a downward direction" and struck the ground.

Passenger Statements (NTSB Form 6120.9) were sent to seventeen passengers. Five passengers returned their Passenger Statements to the NTSB investigator-in-charge (IIC). One passenger reported "the aircraft tilted to the right roughly 45 degrees." Subsequently, the aircraft "righted itself and then tilted back to the left 45 degrees. At no time did the aircraft actually stop at level flight, rather it continued rolling back to the left after the initial right tilt. This time the aircraft tilted to what felt like 90 degrees to the right." Another passenger reported that "5 to 10 seconds after liftoff I felt the [air]plane banking" at 200-300 feet agl. This passenger stated the "engine sounded fine during the entire event." Another passenger recalled that "seconds after leaving the ground the [air]plane started rolling to the right." This passenger felt the airplane "lose lift." The airplane "started to roll left and it felt leveled out" and then the airplane impacted.

During a telephone interview, conducted by the NTSB IIC, and on the Pilot /Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot reported that the airplane was approximately 2,500 feet from the departure end of the runway and 200 feet agl, when the airplane "suddenly rolled to the right at an estimated 30 degrees per second, continued to the right, and reached a 90 degree angle to the ground." He stated that he "maintained control of the airplane," applied full left aileron and left rudder, pushed forward on the control "stick," and leveled the wings of the airplane. During the sequence, the pilot applied maximum power and continued the climb of the airplane. Subsequently, upon realizing that the airplane did not have enough altitude to clear the trees, the pilot reduced the power to idle. The tail of the airplane struck the ground, the left wing struck trees, and the airplane came to rest on an estimated heading of north.

The pilot further stated that he "originally thought there was an asymmetrical lift situation with a possible flap disconnect." However, he recalled "approximately 2 weeks ago that during the takeoff/initial climb the airplane had a bump, roll right, bump, roll left sequence when the airplane flew through a dust devil." An event, "so similar to this accident sequence," that he concluded that the "airplane flew through a dust devil." However, this time the airplane did not have enough altitude for a complete recovery. The pilot stated the winds were from 330-030 degrees at 6 to 8 knots with "extreme" turbulence. He further stated that a band of clouds associated with a front had passed through the area and was about one hour east of the drop zone. The pilot reported that the airplane had accumulated 169.6 flight hours since installation of the TPE-331-10-511C engine and the Hartzell HC-B4TN-5 propeller, and there was "nothing wrong with the airplane."

On the NTSB Form 6120.1/2, the pilot stated that a "better method of detecting whirlwind conditions. I.E. wind streamers mounted on poles along runway to show rotation prior to reaching [the] runway," could have prevented the accident.

At 1153, the weather observation facility at Alliance Airport (20 nautical miles southeast of the accident site) reported clear skies with calm wind.

The FAA inspectors found the airplane in a muddy bog, approximately 250 yards east of the wet grass runway. The left wing was found separated from the airframe, and additional structural damage existed throughout the airframe. The left side of the airplane was crushed and buckled inward. There were two seats installed in the cockpit and two benches installed along the sidewalls of the fuselage in the cabin. On the right side of the cabin, the inspectors found 9 seat belt assemblies of which 4 were fastened. On the left side of the cabin, they found 7 seat belt assemblies of which 4 were fastened. Three seat belts assembles on the left side were pulled loose from the attachments points on the floor of the cabin. The engine controls were found in the full forward position.

The aircraft had been modified in accordance with Supplemental Type Certificate (STC) SA4345NM issued for the model DHC-3 aircraft. The accompanying Airplane Flight Manual (AFM) supplement stated "nine passenger or less seating configuration." The required placard, which was installed in the airplane, stated in part, "THIS AIRPLANE IS LIMITED TO THE OPERATION OF NINE PASSENGERS OR LESS."

The FAA inspectors conducted a personal interview with the pilot. In response to questions about the seating accommodations, seatbelt hookups, and certification of the airplane, the pilot stated that the seating configuration of 9 or less did not apply since the jumpers are not considered "passengers."

The FAA inspectors calculated the takeoff gross weight at 9,118.05 pounds with the center of gravity (CG) at 161.92 inches. The AFM listed the maximum allowable gross weight at 8,000 pounds at an aft CG limit of 152.2 inches. Further, an AFM WARNING stated: C. G. POSITION OF THE LOADED AIRCRAFT MUST BE CHECKED AND VERIFIED PRIOR TO TAKE-OFF, AND APPROPRIATE TRIM SETTINGS SHOULD BE USED; OTHERWISE ABNORMAL STICK FORCES AND POSITIONS MAY RESULT."

According to the aircraft manufactuer, the elevator trim system is operated by a cable and pulley system from a handwheel on the right-hand side of the pilot's seat. The handwheel operates in the natural sense [clockwise/counter-clockwise] and is marked NOSE UP and NOSE DOWN. The pre-flight aircraft check states in part: ELEVATOR TRIM TO MEET CG REQUIREMENTS.

NTSB Probable Cause

the pilot's failure to maintain aircraft control during the takeoff/initial climb. Contributing factors were the pilot's exceeding aircraft weight and balance limits and the dust devil.