27th of August 2012, CFIT - Controlled Flight Into Trees, Blog 717

An Arrow Falcon OH-58C was operating an agricultural ("Crop Dusting") flight, nearly 13 years ago to date. After a 30-minute positioning flight from the helicopter's base, the helicopter landed near an orchard, close to Escalon (California, USA). At this location, the aircraft's hoppers were filled with 80 gallons of chemicals from a truck. After an uneventful take-off, the helicopter started applying the chemicals to the orchard.

Overview of the accident site (© NTSB)

After emptying the hoppers, the aircraft returned to the location of the supply truck to refill the hoppers. When the aircraft was approximately a mile from the truck, the truck driver observed the aircraft bank to the right at a steeper angle than normal. The helicopter disappeared from the truck driver's vision and did not reappear. After seeing the aircraft disappear, the truck driver headed to the area where he had seen the aircraft disappear from sight. He found the aircraft lying on its side in the orchard; it had crashed. Trees close to the crash site were found damaged, and the aircraft sustained extensive damage; there was no post-impact fire The pilot was transported to a local hospital with injuries that were not considered life-threatening.

Close-up of the fuselage (© NTSB)

The pilot stated in the NTSB Form 6120 Pilot Aircraft Accident Report that he had no memory of the accident.

The wreckage was examined by an FAA inspector, who observed the following;

• The tail rotor and engine to transmission drive shafts had separated in shear.

• The tail rotor gearbox rotated freely, and no metal chips were identified on the gearbox chip detector.

• The engine oil level was full, and the lower chip detector was free of metal chips.

• He traced the control system and established control continuity.

He concluded that there were no mechanical malfunctions or failures were found that would have precluded the normal operation of the helicopter.

Tail-rotor and gearbox (© NTSB)

The National Transportation Safety Board concluded that the probable cause(s) of this accident were:

"The pilot’s failure to maintain clearance from trees during a low-altitude agricultural application which resulted in a loss of control and impact with the ground."

Details and additional info on this accident can be found on the website of the NTSB (The Docket) by clicking here.

Bottom view of the helicopter (© NTSB)