ROCKWELL INTERNATIONAL S-2R

Full Narrative

On July 9, 2010, at 1930 eastern daylight time, a Rockwell International S-2R, N4992X, collided with trees and a ditch during an off-airport forced landing following a loss of engine power during an aerial application flight. The airline transport pilot was not injured. Both wings of the airplane received substantial damage. The aircraft was registered to Bob Ruhe Ag Service, Inc., and operated under the provisions of 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed and no flight plan was filed. The local flight originated from Leipsic, Ohio, at 1900.

The pilot reported the engine lost power during the middle of a spray run when he was just above the height of the corn crop. He stated he turned the airplane away from the town and power lines. The airplane contacted small trees and a ditch during the forced landing in a bean field.

An on-scene examination of the engine, a Pratt & Whitney PT6A-34, revealed the power section was seized due to impact damage to the exhaust duct. The gas generator and accessory drives rotated freely by hand. All of the external lines, filters, and screens were normal. The power turbine and power turbine shroud contained light rotational rubbing. The reduction gearbox rotated smoothly by hand.

Further inspection of the engine revealed rotational signatures to the power turbine blade tips and shroud. A teardown of the engine and a functional check of the fuel control unit, high pressure fuel pump, and the propeller governor failed to reveal any failures/malfunctions that would have prevented the engine from producing power. A detailed examination report is contained in the public docket for this accident.