SEA97FA148

While on a flight from Chico, California, to Eugene, Oregon, the airplane crashed about 29 miles south of its destination. Witnesses stated they saw the aircraft turning toward a mown hay field, with its engine cutting out, when it abruptly dropped and impacted the ground from about 100 feet above ground level. Examination of the airplane at the accident site revealed that the aircraft's right wing fuel tank was empty and its left wing tank contained only a trace quantity of fuel. A total of approximately one to two teaspoons of fuel was extracted from the remainder of the aircraft's fuel system. Both wing tanks were breached; however, there was no fuel odor or discoloration of vegetation at the accident site. Examination of the aircraft did not reveal any evidence of mechanical malfunction. The pilot overflew at least five suitable airports with fuel facilities on his route of flight.

History of flight

On June 20, 1997, approximately 1805 Pacific daylight time, a Beech 77, N6630C, collided with terrain approximately 10 miles south of Cottage Grove, Oregon, while on a 14 CFR 91 flight from Chico, California to Eugene, Oregon. The airplane was substantially damaged and the private pilot/owner of the aircraft and one passenger received fatal injuries. Visual meteorological conditions prevailed in the accident area, and no flight plan had been filed for the flight.

The general manager of Pacific Flight Services, Inc., Chico, California, reported that the aircraft was refueled with 19.2 gallons of 100LL aviation gasoline at 1430 on the afternoon of the accident. She stated that the accident pilot told their line service representative to fill the tanks to 1 inch from the top, and that the accident pilot personally verified the tanks were filled to the desired level and replaced the fuel tank filler caps himself. Air traffic control (ATC) records indicated that the aircraft was cleared for takeoff from Chico at 1508. The FAA indicated that there was no record of communication between the accident aircraft and any ATC or flight service station (FSS) facilities other than at Chico during the accident flight. A query to the FAA regarding the availability of ATC radar data on the accident aircraft revealed that none was available.

The straight-line distance from Chico to Eugene is 267 nautical miles, and from Chico to the accident site is 238 nautical miles. The accident site was approximately 29 nautical miles south-southeast of Mahlon Sweet Airport (the Eugene airport) and 9 nautical miles south of the nearest airport to the accident site, Cottage Grove State Airport in Cottage Grove. Individuals with knowledge of the aircraft occupants' travel plans reported that they were not aware of any intermediate stops planned by the pilot between Chico and Eugene. Based on this information and the reported time of the accident, the airplane had been airborne for 2 hours and 57 minutes at the time the accident occurred, with an average straight-line ground speed of 81 knots.

The route of flight from Chico to Eugene traverses the Siskiyou Mountains of northern California and southern Oregon. Public-use airports with fuel facilities suitable to the accident aircraft along the general route of flight include Red Bluff, Redding, and Montague/Siskiyou County in California, and Medford and Roseburg in Oregon. Investigators examined two possible routes of flight from Chico to Eugene for distance and highest terrain: via the V23 Federal airway (which runs from the Red Bluff, California VORTAC, 25 nautical miles northwest of Chico, to Eugene), and following Interstate Highway 5 (I-5), which runs from near Chico to Eugene. Via V23, the ground distance from Chico to Eugene is 273 nautical miles, with terrain under the airway rising to 8,043 feet above MSL in northern California. The highest terrain elevation along I-5 is Siskiyou Summit, a pass just north of the California/Oregon state line, at an elevation of approximately 4,310 feet above MSL; ground distance via I-5 is approximately 355 nautical miles. Based on the distance along I-5 from Chico to the accident area (approximately 325 nautical miles) and the time airborne of 2 hours and 57 minutes, required average ground speed from Chico to the accident area along I-5 was computed to be 110 knots. This ground speed is greater than the highest maximum-power cruise true airspeed (105 knots) given in the performance section of the airplane flight manual. Via V23, average ground speed from Chico to the accident area (approximately 245 nautical miles) was computed to be 83 knots.

The aircraft wreckage was located at the south end of a north/south oriented hay field. The eastern portion of this field, which was approximately 1/4 mile long, was mown to an estimated width of 100 to 200 feet along its entire length, while the grass in the western portion was 1 1/2 to 2 feet high. Witnesses reported that they observed the aircraft initially approach the area in a north-to-south direction at a low altitude, with its engine sputtering. They reported that when the aircraft reached a position approximately over a school playground adjacent to the south end of the hay field, it began a left turn, continuing in this turn to a point approximately on a descending flight path back to the north toward the mown area of the hay field. The witnesses reported that at this point, at an altitude of about 100 feet above ground level, the aircraft's nose dropped abruptly to an attitude they reported variously between 30 degrees nose-down and near-vertical. The aircraft continued downward in this attitude, disappearing from the witnesses' view behind intervening obstructions; the witnesses reported that they heard the crash immediately thereafter. There was no fire.

The accident occurred during the hours of daylight at 43 degrees 39.0 minutes North and 123 degrees 5.0 minutes West.

Aircraft information

Performance information in the Beech 77 pilot's operating handbook (POH) indicates that with full usable fuel of 29 gallons, the airplane's range is 339 nautical miles with a 45-minute reserve at 6,500 feet pressure altitude, 2,700 RPM, zero wind, and mixture leaned to maximum RPM. At this pressure altitude and power setting, the airplane cruises at 105 knots true airspeed (KTAS), with a fuel flow of 7.4 gallons per hour. At 10,500 feet pressure altitude, 2,500 RPM, zero wind, and mixture leaned to maximum RPM, the aircraft's range is given as 396 nautical miles with a 45-minute reserve, with a cruise airspeed of 95 KTAS and a fuel flow of 5.6 gallons per hour.

The aircraft's maximum ramp weight is 1,680 pounds, and its maximum takeoff gross weight is 1,675 pounds. Based on loading conditions determined during the on-scene investigation (1,173-pound aircraft empty weight, 195-pound pilot, 165-pound passenger, and 55 pounds of baggage), the aircraft's fuel tanks could be filled to a maximum quantity of 15.3 gallons total to comply with the aircraft's maximum ramp weight limitation. With the above weights and a full usable fuel load of 29 gallons, the aircraft is approximately 84 pounds over its maximum ramp weight.

Based on the above empty aircraft, passenger, and baggage weights with zero fuel, the aircraft's CG at the time of the accident was computed to be 88.98 inches aft of datum. The aircraft's aft CG limit is 88.9 inches aft of datum.

An invoice with the aircraft records dated September 23, 1994, issued by Aviation West of Cameron Park, California to the aircraft owner at that time, indicated that the aircraft's Lycoming O-235-L2C engine and its propeller had been removed from the aircraft due to a propeller strike, and that the engine was disassembled and inspected using zyglo and magnaflux inspection techniques. According to the aircraft maintenance records, the engine underwent a major overhaul on September 20, 1994, and a new Sensenich 72CKS12-0-50 propeller was also installed on the aircraft on October 7, 1994.

The pilot's father-in-law submitted a copy of a work order from Pacific Flight Services of Chico, dated October 15, 1996, which indicated that the right fuel drain valve had been removed, cleaned, and resealed, and the aircraft approved for return to service, following a leaking right fuel drain. There was no corresponding entry in the aircraft logbook.

The accident aircraft was equipped with an electrical float-type fuel quantity indicating system, with separate quantity indicators for each wing tank. The aircraft was also equipped with a low fuel quantity warning light which is designed to illuminate when total fuel remaining in either tank falls below approximately 2 1/2 gallons. The aircraft logbook indicated that the accuracy of the left and right fuel quantity indicating systems was checked on October 15, 1993, approximately 316 flight ho