Aviation Accident Summaries

Aviation Accident Summary WPR11FA390

Forsyth, MT, USA

Aircraft #1

N7666D

PIPER PA-18-150

Analysis

The operator reported that the pilot and passenger were going to survey a prairie dog town and take pictures. Hunters in the accident area observed the airplane fly overhead and descend below mountainous terrain while in a turn. The airplane crashed in an open field. The airplane damage and the ground scars at the accident site were consistent with the airplane being in a stalled condition at the time of the accident. The pilot likely failed to maintain adequate airspeed as he was increasing the bank angle to maintain visual reference to the ground, which resulted in a stall/mush, loss of control, and collision with terrain. A postaccident examination of the airframe and engine revealed no evidence of a mechanical failure or malfunction that would have precluded normal operation.

Factual Information

HISTORY OF FLIGHTOn August 18, 2011, about 0925 mountain daylight time, a Piper PA-18-150, N7666D, impacted an open area in mountainous terrain near Forsyth, Montana. Big Sky Wildlife Consultants operated the airplane under the provisions of 14 Code of Federal Regulations Part 91 as a contract flight to count prairie dogs. The commercial pilot and one passenger were fatally injured; the airplane was substantially damaged as a result of impact forces and post impact fire. According to friends of the pilot, the two men were going up to take pictures of a prairie dog town and conduct a survey of the population. According to witnesses hunting in the area, they observed the accident airplane fly overhead, descend in a turn below the mountain tops, and then observed smoke. PERSONNEL INFORMATIONThe pilot, age 39, held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane issued March 1, 2011. The pilot held a second-class medical issued on March 11, 2011, with no limitations. No personal flight records were located for the pilot, and the company and family believed that the pilot's logbook was onboard the airplane at the time of the accident. The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) obtained the aeronautical experience listed in this report from a review of the Federal Aviation Administration (FAA) airmen medical records on file in the Airman and Medical Records Center located in Oklahoma City, Oklahoma. The pilot reported on his most recent medical application dated March 11, 2011, a total time of 3,000 hours with 500 hours logged in the last 6 months. AIRCRAFT INFORMATIONThere were no maintenance records available for review; the family believed the airplane maintenance records were onboard the airplane at the time of the accident. According to FAA records, the accident pilot purchased the airplane on November 15, 2006. According to FAA form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance), on February 23, 2010, a Lycoming O-320-B2C, serial number 49324-27AC, engine was installed on the airplane, per Supplemental Type Certificate (STC) SA00522SE. The form also indicated that a continued airworthiness had been accomplished per 100-hour guidelines in Federal Aviation Regulation (FAR) Part 43.2-43.15. AIRPORT INFORMATIONThere were no maintenance records available for review; the family believed the airplane maintenance records were onboard the airplane at the time of the accident. According to FAA records, the accident pilot purchased the airplane on November 15, 2006. According to FAA form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance), on February 23, 2010, a Lycoming O-320-B2C, serial number 49324-27AC, engine was installed on the airplane, per Supplemental Type Certificate (STC) SA00522SE. The form also indicated that a continued airworthiness had been accomplished per 100-hour guidelines in Federal Aviation Regulation (FAR) Part 43.2-43.15. WRECKAGE AND IMPACT INFORMATIONExamination of the accident site revealed that the airplane came to rest upright in an open field on an approximate magnetic heading of 290 degrees. All major structural components of the airplane were located within 30 feet of the main wreckage. A ground scar, located directly under the right wing, 20 inches in length, was observed. An outboard portion of a propeller blade was located next to the ground scar. Examination of the airplane revealed that a majority of the airframe fabric had been consumed by fire. The instrument panel was consumed by fire. The throttle handle was bent, and observed in the full forward position. Engine continuity was established from the throttle handle to the engine. The flap handle appeared to be in the "down" position, consistent with the flaps being retracted. Flight control continuity was established throughout the airplane from the cockpit controls to all primary flight control surfaces. A report is attached to the public docket for this accident The visual examination of the engine revealed that it remained partially attached to the airframe and exhibited fire and thermal damage. All four cylinders remained attached to the engine crankcase. The propeller remained attached to the engine crankshaft propeller flange. Both propeller blades exhibited S-bending with chord wise scratching. A detailed report is attached to the public docket for this accident. MEDICAL AND PATHOLOGICAL INFORMATIONA postmortem examination was conducted by the Forensic Medicine and Pathology, PLLC, Billings, Montana, on August 19, 2011. The cause of death was reported as smoke inhalation, secondary to fire following an airplane crash. The FAA's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot, with no carbon monoxide, cyanide, or volatiles, or tested drugs detected.

Probable Cause and Findings

The pilot’s failure to maintain adequate airspeed while maneuvering, which resulted in a stall/mush, loss of control, and impact with terrain.

 

Source: NTSB Aviation Accident Database

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