Raywood, TX, USA
N948BB
Air Tractor AT-502A
The airplane collided with trees while departing from a private grass airstrip. The departure surface was a grass strip that stretched about 2,000 feet long, with trees located at the end. The Airplane Flight Manual for the AT-502A states that 10 degrees of flaps should be set for takeoff. The pilot reported that his takeoff procedure consisted of starting the takeoff roll with the wing flaps in the retracted position until rotation, where he would he would start the initial climb by pulling back on the control stick while simultaneously lowering the flaps to the 10-degree extended position. The pilot stated that he used this procedure in an effort to decrease the ground roll. Following his procedure, the pilot applied full engine power and the airplane started the takeoff roll down the grass strip. As the airplane's groundspeed increased, he moved the flap control to extend the wing flaps and rotated the airplane to a nose high attitude. The airplane lifted off the grass surface, but the wing flaps failed to extend. The airplane climbed to about 15 feet, flew down the runway in ground effect, and collided with tree branches, then descended into the terrain. During an examination of the cockpit, a Federal Aviation Administration inspector observed the flap circuit breaker to be in the "out" position. The airplane's manufacturer stated that applying the wing flaps after starting the departure roll is an improper takeoff procedure. The manufacturer further stated that the drag created by the wing flaps at 10 degrees is negligible during takeoff roll phase of operation, and keeping them retracted will not decrease the takeoff distance by a measurable amount. An examination of the flap system failed to find a problem with the system operation or determine why the circuit breaker was in the open position.
On June 3, 2003, about 0930 central daylight time, an Air Tractor AT-502A, N948BB, collided with trees after departing from a private grass strip near Raywood, Texas. M&M Air Service of Beaumont, Inc., was operating the airplane under the provisions of 14 CFR Part 137 as a local aerial application flight. The commercial pilot, the sole occupant, sustained minor injuries; the airplane was destroyed. Visual meteorological conditions prevailed, and a flight plan had not been filed. A Federal Aviation Administration (FAA) inspector examined the airplane after the accident occurred and interviewed the pilot. The intended departure surface was a grass strip that stretched about 2,000 feet long, with trees located at the end. The pilot reported that his standard takeoff procedure consisted of starting the takeoff roll with the wing flaps in the retracted position, and continuing in that configuration until rotation. Upon rotation, he would start the initial climb by pulling back on the control stick, while simultaneously lowering the flaps to the extended 10-degree position in an effort to decrease the ground roll distance. The reasoning behind doing such a departure was based on the pilot's belief that keeping the wing flaps retracted at the beginning portion of the takeoff roll reduces drag and therefore, decreases the airplane's takeoff distance. The pilot further stated to the FAA inspector that prior to departure, the airplane was refueled, and the hopper was loaded with about 500 gallons of herbicide. Abiding by his standard procedure, the pilot applied full engine power, and the airplane started the takeoff roll down the grass strip. As the airplane's groundspeed increased, he extended the wing flaps and configured the airplane in a nose high attitude. The airplane lifted off the grass surface, but the wing flaps failed to extend. The airplane climbed to about 15 feet and encountered tree branches. While on scene, the FAA inspector noted broken branches about 12 feet high on the trees, which were located 128 feet from the end of the grass strip. The broken tree limbs continued in a descending pattern toward the main wreckage, which was about 500 feet from the end of the grass strip. During an examination of the cockpit, the inspector observed the flap circuit breaker to be in the "out" position. The Air Tractor's Airplane Flight Manual, states that the procedure for performing a short field takeoff consists of lowering "flaps to 10-degree position (first mark)." It does not specify when flap extension should occur. According to a representative at Air Tractor, applying the wing flaps after starting the departure roll is an improper takeoff procedure. He further stated that the drag created by the wing flaps is negligible during this phase of operation, and will not decrease the takeoff distance by a measurable amount.
the pilot's encounter with a stall/mush condition in the takeoff initial climb due to his inadequate preflight/pretakeoff procedures and failure to set the wing flaps to the proper takeoff configuration before beginning the takeoff ground roll.
Source: NTSB Aviation Accident Database
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