SEA98LA095

While engaged in spraying pesticide over rye grass along a rural road, the Grumman 'AgCat' biplane impacted several power/phone lines which the pilot reported he did not see. The lines were unmarked. The power poles supporting the lines were approximately 1,000 feet apart and the catenary would have been near its low point in the vicinity of the crossing point (diagonally) over the road.

History of flight

On June 12, 1998, approximately 1255 Pacific daylight time, a Grumman G-164B "AgCat" biplane, N8252K, registered to and being operated by BMA, Inc., doing business as Blue Mountain Aviation, and being flown by a commercial pilot, was destroyed when the aircraft impacted power and telephone lines approximately five nautical miles northwest of Starbuck, Washington. The aircraft subsequently impacted terrain and was consumed by a post crash fire. The pilot sustained serious burn injuries. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was engaged in the application of a pesticide (roundup), was to have been operated under 14CFR137, and originated from Walla Walla, Washington, earlier on the day of the mishap. There were no known witnesses to the wire strikes and subsequent ground impact of the aircraft.

The pilot, while in Harborview Hospital in Seattle, reported to the operator that "when he entered the field he hit two power lines that were unmarked" and that "he was unaware that they were there." The pilot reported that he "did three complete barrel rolls before impacting the ground" and that "at no time prior to this did (he) the pilot experience any engine problem."

The operator reported to the Investigator-in-charge that the pilot had completed spraying the site, having consumed most of the pesticide load he had been carrying, and was then asked by the property owner if he would also spray some roundup along the rye grass on his land alongside Fletcher Road with some of the remaining pesticide. It was not known how much fuel remained at this point (refer to photographs showing the extensive fire damage).

The operator also reported that the pilot routinely wore corrective lenses, as dictated by the limitation on his medical certificate, and that he was wearing glasses at the time of the accident. A pair of melted glasses were found amongst the wreckage. The pilot was not wearing a Nomex fire resistant flight suit at the time.

The airframe logbook for N8252K contained an entry dated 02/10/80, showing a Federal Aviation Administration (FAA) signoff for a maximum demonstrated operating weight of 7,020 pounds. The aircraft's total operating, exclusive of a full spray load, and with a full load of fuel (80 gallons), pilot weight, and oil weight, added to the aircraft's basic empty weight was reported to be 4,351 pounds. The total weight of the spray load, assuming a full 300 gallon hopper would have been 7,020 pounds minus 4,351 operating weight, or 2,669 pounds of spray load maximum.

The temperature (79 degrees F.), altimeter setting (29.94 in Hg), and airport elevation (1,205 feet above sea level), resulted in a calculated density altitude of approximately 2,800 feet at the time (1250 PDT) of the accident 27 nautical miles north.

On site examination conducted by an FAA inspector from the Spokane Flight Standards District Office late on the afternoon of the accident date determined that the aircraft came to rest on Fletcher Road at 46 degrees 33' 07" north latitude and 118 degrees 13' 59" west longitude (refer to Chart I). The aircraft impacted power and telephone lines oriented approximately northwest-southeast with one set of dual poles located on the north side of the road nearly abeam to the aircraft's final resting place, and the other set of dual poles located on the south side of the road and approximately 1,000 feet further east of the aircraft's final resting place (refer to panoramic photograph 1). It is not known what the height was above the road at the catenary low point for these wires. The aircraft came to rest in the road with it's tail oriented toward the west-northwest (refer to photograph 2). One of the lower wingtips was located in the grass a short distance south of the south edge of the road (refer to photograph 3). This wingtip was observed at a point slightly south of the road and slightly west of where the wires would have crossed the road diagonally, and with the aircraft's ground impact and final resting place several hundred feet further west (refer to photograph 4). The wingtip displayed no evidence of fire and had no tip navigation light installed. The fiberglass wingtip had been torn from its wing structure attach rivets which secure it to the lower wing outboard end (refer to photograph 5). The Pratt & Whitney R-1340 engine was severely damaged by the post crash fire. Its propeller displayed chordwise scratching as well as blade twist and bending deformation, and a section of the wire impacted was observed draped over the engine (refer to photograph 6).