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N6630C accident description

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Tail numberN6630C
Accident dateJune 20, 1997
Aircraft typeBeech 77
LocationCottage Grove, OR
Additional details: None

NTSB description

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 hours before the accident.

According to the Beech 77 pilot's operating handbook (POH), at a gross weight of 1,590 pounds, flaps up, and power idle, the aircraft's stall speed is 53 KIAS at 0 degrees bank angle and 56 KIAS at 30 degrees of bank. The POH states that the maximum altitude loss during a normal stall recovery is approximately 300 feet. The POH gives the aircraft's maximum glide and engine-out approach airspeed as 63 KIAS.

METEOROLOGICAL INFORMATION

The San Francisco, California area forecast (FAUS6, KSFO, June 20, 1997, 1945 Coordinated Universal Time [UTC]) forecast VFR conditions with generally clear skies for the entire route of flight from Chico to Eugene for the time frame of the accident flight.

Winds aloft forecasts applicable to the route of flight for use at the time of the accident (FDUW04, KWBC, June 20, 1997, 1640 UTC) included the following: Red Bluff, California - 310 degrees at 16 knots at 3,000 feet above mean sea level (MSL), 310 degrees at 13 knots at 6,000 feet above MSL, 300 degrees at 13 knots at 9,000 feet above MSL, and 290 degrees at 17 knots at 12,000 feet above MSL; Montague, California - 300 degrees at 12 knots at 6,000 feet MSL, 280 degrees at 11 knots at 9,000 feet MSL, and 270 degrees at 17 knots at 12,000 feet MSL; North Bend, Oregon - 300 degrees at 12 knots at 3,000 feet MSL, 260 degrees at 9 knots at 6,000 feet MSL, 260 degrees at 15 knots at 9,000 feet MSL, and 270 degrees at 23 knots at 12,000 feet MSL (all directions true.) The initial straight-line true course from Chico to Eugene is 347 degrees.

The FAA indicated that there was no record of the pilot receiving a preflight weather briefing.

WRECKAGE

Investigators from the NTSB, FAA, Raytheon Aircraft, and Textron Lycoming responded to the accident site and performed an on-site examination of the aircraft wreckage on June 21, 1997. 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. The accident site was approximately 2 nautical miles east of the V23 airway centerline and approximately 5 nautical miles east of I-5.

Investigators found all aircraft components at the accident site. The aircraft was resting upright in approximately a 45-degree nose-down position, on a heading of 329 degrees magnetic. An east-west oriented wire mesh fence ran underneath the aircraft's tail. The fence was undamaged. A 6-foot long ground scar, pointing generally toward the main wreckage, was located with its far end 23 feet west of the main wreckage. Another ground scar was located 7 feet northwest of the main wreckage.

The engine cowl had separated from the aircraft, and was located 26 feet northeast of the main aircraft wreckage. The aircraft's engine was displaced aft, tilted aft end up, and rotated clockwise approximately 30 degrees (as viewed from the pilot's seat) relative to its normal installed position. Both propeller blades exhibited slight torsional twisting and chordwise scratching, with one blade pushed about 15 degrees aft of the normal plane of propeller rotation at about 6 inches from the propeller hub, but both blades were otherwise generally straight. The entire propeller remained attached to the engine.

The aircraft's right wing remained on the aircraft in its normal position, but was twisted to a higher incidence angle at the tip than at the root. The right flap and aileron remained attached to the wing. The left wing had separated and was adjacent to the fuselage, but rotated approximately 45 degrees forward (clockwise, as viewed from above the aircraft) of its normal position. The left aileron and flap had separated from the wing trailing edge. The left aileron and flap remained attached to their coaxial torque tubes, which protruded from the fuselage in approximately their normal position. The left aileron was bent back over the flap, with the bend point about 8 inches outboard of the face between the aileron and flap. The flap system actuator components were found in a position corresponding to flaps retracted. The aircraft's empennage was twisted approximately 90 degrees counterclockwise relative to the fuselage and was also bent upward approximately 90 degrees relative to the fuselage, such that the leading edge of the vertical fin faced the left side of the tail cone. The empennage was otherwise generally intact.

Instrument indications observed in the aircraft wreckage included the following. The outer portion of the airspeed indicator needle was broken off, and the surviving portion pointed to approximately 67 knots indicated airspeed (KIAS). The engine tachometer indicated approximately 1,125 RPM. The engine instrument cluster indicated as follows: ammeter 2/3 full scale discharge; fuel pressure 0 PSI; oil temperature 120 degrees (at the top of the white arc and just below the green arc); oil pressure 0 PSI; and both fuel tanks empty. The aircraft's communications radio was found set to 118.90 MHz (the Eugene air traffic control tower frequency), and its VHF navigation radio was found set to 112.90 MHz (the Eugene VORTAC frequency.)

Investigators found no evidence of preimpact mechanical deficiencies in the airframe or engine. Investigators also found 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 open; however, there was no fuel odor or discoloration of vegetation at the accident site. Inquiries to witnesses who responded to the accident scene within two to ten minutes of the crash also disclosed that they did not notice any smell of fuel at the time of the accident.

No documentation resembling a flight plan or navigation log for the accident flight was found in the aircraft wreckage, at the accident site, or in the victims' personal effects. Sectional charts covering the route of flight from Chico to Eugene were found in the wreckage; however, they were not current editions.

The victims' baggage and personal effects were removed from the aircraft and weighed, and were found to weigh a total of 55 pounds.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies on the pilot and passenger were conducted by the Oregon State Medical Examiner's Office, Portland, Oregon. Both autopsies were conducted on June 23, 1997. The cause of the pilot's death was given as chest trauma with aortic transection. The cause of the passenger's death was given as multiple injuries including cervical (neck) fracture.

Toxicology tests on the pilot were conducted by the FAA Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma. The CAMI toxicology tests screened for carboxyhemoglobin, cyanide, ethanol, and drugs, and did not detect any of these substances.

SURVIVAL ASPECTS

The accident was witnessed. Witnesses called for emergency aid immediately and responded to the accident scene to render assistance. The first individuals arrived at the accident scene within approximately 2 minutes. These individuals reported that they found no signs of life in the victims. A Lane County Sheriff's Office search and rescue incident report stated that officers arrived on scene at 1835, and that both aircraft occupants appeared to be dead on arrival.

TESTS AND RESEARCH

The aircraft's fuel quantity transmitters, engine instrument cluster, and low-fuel warning lamp were removed from the aircraft and sent to the FAA Aircraft Certification Office (ACO), Wichita, Kansas, for functional tests of the fuel quantity indicating and low-fuel warning systems. Testing was accomplished at the facilities of Raytheon Aircraft in Wichita under the supervision of officials of the Wichita FAA ACO. Raytheon's report on this testing noted that both fuel sending units, as well as the engine instrument cluster, had sustained damage from impact, and reported the following results.

The fuel sending units employ floats in the tank to measure fuel level, which are mechanically connected to variable resistors that send an ele

(c) 2009-2011 Lee C. Baker. For informational purposes only.