MORELAND, ID, USA
N50963
Air Tractor AT-402A
The (PIC) pilot-in-command (prospective buyer) was given an oral checkout and training by a representative of the aircraft sales distributor and then he departed on his first flight. He had never flown this make/model, and reportedly had no turbine/turbo-prop experience. He had accumulated over 600 hours in a reciprocating powered crop duster with similar flight characteristics. Several witnesses reported observing the aircraft in a spin, and on-site examination revealed that the aircraft impacted in a slight nose/right wing low, inverted attitude with no forward momentum. No witnesses observed the entry maneuver that led to the inverted spin. The engine was disassembled and no evidence of mechanical malfunction was found. The weight and center of gravity was within limits at the time of the accident.
HISTORY OF FLIGHT On Friday, March 13, 1998, approximately 1400 mountain standard time, a turbo-prop Air Tractor, AT-402A, N50963, registered to and operated by Queen Bee Air Specialties, Inc., and being flown by a commercial pilot, was destroyed during collision with terrain following a loss of control in flight while maneuvering approximately 7 nautical miles northwest of Moreland, Idaho. The pilot was fatally injured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight, which was a pre-purchase demonstration/familiarization, was to have been operated under 14CFR91, and originated from the Blackfoot airport, Blackfoot, Idaho, approximately 1345. A representative of the owner/distributor for the aircraft arrived at the Blackfoot airport in N50963 approximately 1230 in anticipation of completing the accident pilot's training in the aircraft. A pre-sales demonstration flight by the accident pilot was to follow. The representative stated that he "had previously spent time familiarizing him (the pilot) with the turbine Air Tractor series." With the pilot in the cockpit, the representative completed the training discussing various aspects of the aircraft and differences/similarities between the accident aircraft and the AT-301 aircraft which the pilot was familiar with. The representative reported in an interview with an FAA inspector that "he viewed (the) video with (the pilot) then briefed (him) in the cockpit for about 1 hour." The pilot then started the engine and taxied the aircraft out departing to the west. The representative observed the aircraft for a period of time and then made a telephone call after which he did not see the aircraft in flight again (refer to ATTACHMENT K-I). A couple located approximately 1/2 mile south of the crash site (refer to DIAGRAM I) reported hearing "a plane to the north of us" and that it "sounded like someone going back and forth in a field." They also reported observing "a small yellow plane (spray-plane type) in a slow spiral nose-dive" (refer to ATTACHMENT B-I). PERSONNEL INFORMATION The FAA on-site inspector reviewed the pilots flight logs and reported that as of May 14, 1997, the pilot had logged 8,756 hours, and the majority of his flight time was in the Piper PA-25 aircraft. He reported that the pilot's family estimated his total flight time as 9,800 hours. Additionally, the FAA inspector reported that the pilot logged approximately 217 hours and 397 hours in the Air Tractor model 301 aircraft for the 1996 and 1997 spray seasons respectively. He reportedly had no turbine or turbo-prop flight experience and had never flown the Air Tractor 402A aircraft. The FAA inspector reported that the handling characteristics of the Air Tractor models 402 and 301 are similar. The model 301 is a reciprocating engine powered agricultural aircraft with a typical empty weight (including spray equipment) of 3,800 pounds, a 600 horsepower Pratt & Whitney radial engine, a 270 square foot wing area, a 45.1 foot wingspan, and a stall speed as usually landed of 56 mph. The pilot's weight, according to his second class FAA physical conducted April 28, 1997, was 171 pounds. AIRCRAFT INFORMATION The model 402A is a PT6A powered agricultural aircraft with a typical empty weight (including spray equipment) of 3,930 pounds, a 550 horsepower Pratt & Whitney turbo-prop engine, a 306 square foot wing area, a 51 foot wingspan, and a stall speed as usually landed of 53 mph. According to the airplane flight manual, the model 402A aircraft's forward center of gravity boundary was +17.5 inches aft of datum. The aft center of gravity boundary was +24.0 inches aft of datum at 7,000 pounds increasing to 28.0 inches aft of datum at 6,400 pounds (refer to ATTACHMENT FM-I). Information for determining the center of gravity for N50963 under specific configurations was documented in the Airplane Flight Manual (refer to ATTACHMENT FM-II). The center of gravity of the aircraft at the time of the accident was calculated based on the information from these two attachments as well as the estimation of 100 gallons of fuel aboard, a pilot/clothing weight of 180 pounds, no payload, and no rinse water load. The center of gravity was calculated as 25.5 inches aft of datum (refer to ATTACHMENT CG-I). The Airplane Flight Manual specifically advised the reader under "MANEUVER LIMITS" "No acrobatic maneuvers, including spins, are approved." Additionally, the Airplane Flight Manual states under "SPINS" in the emergency procedures section that "The spinning characteristics of this aircraft have not been fully investigated and spin recovery techniques have not been established." Suggested procedures in the event of an inadvertent spin are then outlined (refer top ATTACHMENT FM-III). METEOROLOGICAL INFORMATION One of the deputies on site reported that the weather on the afternoon of the accident was "good" with "light winds," "scattered clouds," visibility unrestricted," and "temperature about 55 degrees F(ahrenheit)." WRECKAGE AND IMPACT INFORMATION A deputy with the Bingham County Sheriff's department arrived on-site following the accident and reported the following observations: "As I approached I could smell a strong odor of what I suspected to be fuel. The plane was lying on its top side with the nose facing west." He reported the crash site as being "muddy" (from Bingham/Blackfoot Joint Law Enforcement Report OR1998-00505). The on-site FAA inspector reported that the aircraft's principal ground scar depth was approximately 10 inches and that there was no ground scar track across the field. The aircraft's tail-wheel was observed to be free of any dirt or mud. Both main wheels, however, displayed dried mud and dirt on the lower halves of their tires. The vertical stabilizer and rudder displayed compressive deformation at its upper extremity and the aircraft was observed to be embedded in the soil with the engine/propeller buried deep into the mud and the top of the vertical stabilizer resting on the ground. The right wing was observed to be twisted about its lateral axis clockwise (when looking from tip to fuselage at the site) and displayed a greater amount of upper leading edge deformation that the left wing (refer to photographs 1 through 4). Both wing flaps were observed in the retracted position. MEDICAL AND PATHOLOGICAL INFORMATION Post mortem examination of the pilot was conducted by Gary Ellwein, M.D., at the Eastern Idaho Regional Medical Center, Idaho Falls, Idaho, on March 14, 1998. Toxicological evaluation of samples from the pilot was conducted by the FAA's Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma. All results were negative with the exception of a finding of 0.86 ug/ml salicylate in urine. TESTS AND RESEARCH The Pratt & Whitney PT6A-11AG turbo-prop engine was examined at the facilities of Queen Bee Air Specialties, Inc., Rigby, Idaho, March 16-17, 1998, under the oversight of an FAA inspector. No evidence of any mechanical malfunction was noted during the examination (refer to attached P&W report). ADDITIONAL INFORMATION On-site examination was conducted by an FAA inspector assigned to the Salt Lake City Flight Standards District Office. He subsequently released the airframe (excluding the engine) to the owner on March 15, 1998. Subsequent to the engine examination, a second FAA inspector from the same office released the engine on March 18, 1998, (refer to NTSB Form(s) 6120.15). The aircraft's logs and records were returned to the owner via Federal Express shipping on January 22, 1999.
The pilot's failure to maintain aircraft control resulting in an inadvertent stall/spin. A factor was his lack of familiarity in the make/model.
Source: NTSB Aviation Accident Database
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