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On October 22, 1997, approximately 1340 central daylight time, a Weatherly 620B agricultural airplane, N46278, owned and operated by Paducah Ag-Air Service Inc., of Paducah, Texas, was destroyed when it impacted the ground subsequent to contacting power lines, near Cee Vee, Texas. The non-instrument rated commercial pilot received fatal injuries. Visual meteorological conditions prevailed and no flight plan was filed for the Title 14 CFR Part 137 aerial application flight. The flight originated from the Dan E. Richards Municipal Airport, Paducah, Texas, at 1330.
Witnesses reported that they observed the airplane spraying the field they were working in prior to the accident. The witnesses indicated that the airplane was flying level when it passed behind trees and out of their view. These trees masked the power lines from the witnesses view. Approximately 5 to 10 seconds after the airplane went out of their view, they saw "black smoke." One witness reported that he went to the accident site, and found power lines that were "severed and stretched to the ground." He saw the airplane "in a cotton field and engulfed in flames."
According to the pilot's most recent medical application, dated July 24, 1997, the pilot had accumulated a total of 7,100 hours of flight time, of which 300 were flown in the previous 6 months. The pilot's logbook reflected that he had flown the Weatherly 620B a total of 186 hours, of which 109 were flown in the last 90 days.
The 1991 Weatherly model 620B, serial number 1550, was purchased by the operator on March 3, 1997. At the time of the airplane's last annual inspection on February 4, 1997, the logbook indicates that the airframe had accumulated a total of 1,486 hours. No records were available after February 4 to validate further flight time and maintenance activity.
The restricted category airplane was equipped with a Pratt and Whitney, R-985-AN-1 radial engine, serial number 23409, rated to produce 450 horsepower. The engine had accumulated a total of 325 hours (total time since major overhaul) as of the last annual inspection. The airplane was equipped with a Hartzel, 3-bladed, constant speed propeller, model number HCB3R30-4, serial number E-7236.
The airplane was equipped with a 355 gallon hopper tank. The operator reported that the pilot was spraying the fields with methyl parathion (liquid/toxic) when the accident occurred.
A review of the available airframe and engine maintenance records by the NTSB Investigator-In-Charge (IIC) did not reveal evidence that uncorrected maintenance defects existed prior to the flight.
At the time of the accident the nearest weather observation facility, located 15 miles north of the accident site, reported clear skies, visibility 10 miles, and winds from 170 degrees at 9 knots.
The entire wreckage area, including ground impressions and debris, encompassed an area approximately 170 feet long and 50 feet wide. The centerline axis along the energy path was orientated approximately 090 degrees magnetic. Severed power lines were situated approximately 800 feet west of the main wreckage. A severed portion of wire was observed embedded in the left elevator. A shallow crater approximately 1 foot deep was located 750 feet east of the power lines. Damaged cotton crop continued for 50 feet east of this initial impact crater. The airplane came to rest upright at the end of this damaged crop swath on a heading of about 320 degrees magnetic.
The first major airplane component located along the debris path (approximately 170 feet west of the main wreckage) was a section of the left elevator. Approximately 100 feet west of the main wreckage were ground impressions corresponding to the landing gear. The next major components were found at the initial impact crater (52 feet west of the main wreckage). They were, portions of the blower blades (which are normally attached to the blower assembly on the bottom of the airplane), and wing struts. Sections of power lines were observed throughout the debris path. The Gates City Power Company reported that the wire was 0.257 inches in diameter and consisted of seven aluminum strands wrapped around one tensile steel strand and had a tensile strength of 2300 pounds. According to the local utility company, the wire was 60% aluminum and 40% steel.
The empennage, including the elevators and vertical stabilizer, were not consumed by fire. Control cable continuity was established from just behind the cockpit to the rudder and elevator control surfaces. The control cables from 2 feet behind the cockpit to the rudder pedals and control column were embedded in molten aluminum from the post impact fire, but appeared to be intact.
The area from about 2 feet behind the cockpit forward was consumed by the post impact fire, leaving the frame of the cockpit as the only identifiable part. No instrument readings or switch positions could be validated. The right wing was destroyed and 1/4 of the left wing (inboard) was consumed by the post impact fire. Aileron control cable continuity was established from the wing root to the control surfaces for the left and right wings. The control cables from the wing root to the control column were embedded in molten aluminum resultant of the post impact fire.
The engine was found separated airframe about 165 feet west of the power lines. The engine remained intact and all accessories remained attached, except for the oil sump. The air inlet pipes, located at the rear of engine, appeared crushed. All fuel and oil lines were found continuous and safety wired.
The propeller hub remained attached to the engine. The propeller cylinder and piston assembly remained attached to the propeller hub. Two of the three propeller blades exhibited chordwise scoring and "S" bending, and approximately 1/4 of each blade span (outboard to the tip) was embedded in the ground. Approximately 1/3 of the third propeller blade exhibited aft bending (approximately 90 degrees).
Examination of the wire cutter (P/N 50612-026), located on the left main landing gear strut contained a deformed section that exhibited evidence of metal transfer. Furthermore, the left main landing gear strut contained longitudinal scratches which exhibited a braided pattern, consistent with the braid pattern of the downed power line.
All of the major structural components of the airplane and control surfaces that were not consumed by the post-crash fire were identified. No evidence of an in-flight fire, or structural component failure prior to impact was found.
MEDICAL AND PATHOLOGICAL INFORMATION
The pilot held a valid second class medical certificate, dated July 24, 1997. The certificate stipulated that the pilot was to wear glasses for near vision.
An autopsy was performed by The Southwestern Institute of Forensic Sciences in Dallas, Texas, on October 23, 1998. The cause of death was stated to be multiple blunt trauma.
Toxicological tests were performed by the FAA Civil Aeromedical Institute, Oklahoma City, Oklahoma. All tests were negative.
A post impact fire consumed the airplane.
The pilot was wearing a flight helmet, which was recovered at the accident site, 15 feet forward of the cockpit.
The airplane was equipped with a safety belt and shoulder harness pilot restraint system. The restraint system was consumed by fire. The pilot was recovered from the cockpit area of the wreckage.
The airplane was equipped with a cable deflector extending from the top of the windshield to the top of the vertical stabilizer. This deflector was designed to protect the empennage and tail from wire strikes by deflecting wires over the top of the airplane. Additionally, the leading edges of the two main landing gears and the frontal area of the windshield were equipped with cable cutters (reference enclosed aircraft marketing brochure).
TEST AND RESEARCH
The wire cutter assembly (reference enclosed illustrated parts breakdown and aircraft marketing brochure, courtesy of Weatherly Aviation Co., Inc.) from the left main landing gear strut was sent to the NTSB Materials Laboratory in Washington, D.C. Examination revealed that the attachment bracket for the wire cutter located on the left main strut separated as a result of overstress.
The wire cutter had an approximately 1.25 inch tall by 0.5 inch deep section missing from the leading edge just above the lower mounting bracket. The curled edges and smeared metal at the missing section were consistent with a relative outboard to inboard movement of a foreign object.
The region of the missing section was cut from the larger piece and examined with a scanning electron microscope. Several areas of smeared and transferred material were found. The transferred material was established to be a 6000 series aluminum alloy. The metal composition of the aluminum wire cutter base was a 2000 series aluminum alloy. (Reference enclosed NTSB Materials Laboratory Factual Report)
No NTSB Pilot / Operator Report Form (NTSB 6120.1/2) was received from the operator. The wreckage was released to the owner's representative on November 19, 1997.