Air Tractor Inc AT-502B N5128U accident near Newellton, Louisiana

Probable cause

The pilot's inadequate takeoff planning and his use of an improper flap setting, which resulted in a runway excursion and collision with terrain during takeoff.

NTSB analysis

The pilot reported that, during the takeoff, the airplane's tail rose when the airplane was about halfway down the runway, but the airplane did not get airborne. The airplane exited the end of the 2,750-foot-long, 75-feet-wide, asphalt runway; struck a road embankment; and continued rolling about 600 feet into a cotton field, which resulted in substantial damage to the wings and empennage. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. The examination of the airplane's electric flap actuator jackscrew revealed that it was extended out about 2.5 inches, which indicates that the flaps were set at 20 degrees at the time of the accident.

The pilot reported that the operating weight at the time of the accident was 10,283 lbs and that the airplane's maximum gross weight was 10,480 lbs; however, the airplane flight manual specified a maximum certificated takeoff weight of 8,000 lbs. Regulations and guidance related to agricultural application flights in restricted-category airplanes allowed for operations at weights up to 31 percent above the certificated gross takeoff weight, or 10,480 lbs; however, the airplane manufacturer did not authorize takeoffs with flaps extended more than 10 degrees. Performance data indicated that, at a maximum certificated gross weight of 8,000 lbs with 10 degrees of flaps, a takeoff distance on a hard surface runway of about 2,800 feet was required. The airplane flight manual did not contain takeoff data for weights or flap settings more than 8,000 lbs and 10 degrees, respectively; however, a 2,750-foot-long runway was inadequate.

Text from the NTSB. Open the NTSB docket for CEN12LA500 for the full record.