Ayres Corporation S2R-T34 N357CA accident near Hertford, North Carolina

Probable cause

The in-flight collision with terrain for undetermined reasons.

NTSB analysis

During the pilot's first flight in the accident make and model airplane, he performed multiple spray passes simulating spray application. Most of the spray passes were consistent in terms of heading, altitude, etc., as recorded by the on-board global positioning system (GPS) receiver. The chief pilot, who was flying another company airplane at the time of the accident, noticed the accident pilot returning to the home base and asked him if he was landing. The accident pilot responded that he wanted to go back and make a few more passes. Readout of the GPS receiver revealed that during the last 22 seconds of flight, the heading remained nearly constant at 030 degrees, the altitude decreased to an adjusted value of 48 feet above ground level, and the groundspeed increased to the last recorded value of approximately 152 mph. A witness familiar with agricultural spray operations reported hearing a normal propeller sound during the last 2 to 3 spray passes; however, during the last pull-up and turn maneuver, the witness stated that the sound from the propeller was not the same at the end of the procedure as it had been previously. He reported that it started low and then became louder and at a higher pitch that seemed to remain elevated a moment too long before he heard the sound of the impact. The airplane came to rest inverted in a corn field approximately 1220 feet and 223 degrees from the last recorded GPS data point, though no determination could be made as to what maneuver(s) was or were performed during the last portion of the flight. No swath thru the corn was noted and there was no evidence of forward energy displacement on the ground. Inspection of the airplane revealed extensive damage to the left wing, consistent with ground contact first. There was no evidence of preimpact failure or malfunction to the flight controls, engine, or propeller. At the time of impact, all propeller blades were in the normal operating range.

Although the airplane was equipped with a Pratt and Whitney PT6A-27 model engine, which was not called for in the airplane type certificate, the airplane had been flown in that configuration since March 1992. The PT6A-27 is an approved engine for a S2R-T15 airframe, which according to the engineering manager for the airplane type certificate holder, is nearly identical to the accident airframe and as such would not result in any unusual flight characteristics. Recent work to the airplane within the last month consisted of reinstallation of the power section and a new propeller. The removal of the propeller 11 days before the accident was to replace the spinner dome; the propeller was reinstalled 4 days before the accident. Earlier on the day of the accident the airplane was flown by the chief pilot of the operator for approximately 14 minutes. The only reported discrepancy related to the flight was associated with the agricultural spray nozzles.

Text from the NTSB. Open the NTSB docket for ERA09LA394 for the full record.