BLACK DIAMOND, WA, USA
N3674P
CESSNA P210N
The pilot advised Air Traffic Control that his aircraft had sustained a loss of power while he was engaged in aerial photography operations over mountainous terrain near Mt. Rainier. He elected to attempt to glide from over 10,500 feet above sea level to an airstrip suggested by ATC as a possible forced landing site. During the descent the engine lost total power. The aircraft crashed into trees on the north side of a river with a paved road along its south shore, and within about a mile of an abandoned airstrip. Disassembly and inspection of the engine revealed internal failure due to oil starvation. A B-nut on an oil line to the turbocharger was found to be loose. Maintenance records showed that this oil line had been subject to recent maintenance by company personnel.
HISTORY OF FLIGHT On September 10, 1995, approximately 1155 Pacific daylight time, a Cessna P210N, N3674P, was destroyed when it collided with terrain during an emergency descent after the loss of engine power. The commercial pilot, who was the sole occupant of the aircraft, was fatally injured. Visual meteorological conditions prevailed at the time of the flight, which was an aerial photography flight conducted under 14 CFR 91. The aircraft had departed Eugene, Oregon, about 0930, with a company flight plan, and was expected to return to Harrisburg, Oregon, at the end of the aerial photography flight. The aircraft and ELT were consumed by post-crash fire. Approximately 1141, the pilot called Seattle Air Route Traffic Control Center (ARTCC) declaring an emergency, advising that he had a power loss and was descending, 20 miles north of Mount Rainier. At 1143, N3674P was given a discrete transponder code by Seattle ARTCC. Radar contact was established, and the controller inquired if the pilot was familiar with Bandera airport. The pilot of N3674P stated that he was not. Radar data shows that the aircraft overflew the site of a former airstrip, Lester State Airport, which had been washed away by floods ("A" on attached depiction). The following communications are extracted from an FAA transcript of Seattle Approach communications with N3674P. The entirety of the transcript is attached. A depiction of the flight path, overlaid upon quad maps, was generated by investigators and is attached, showing the aircraft's radar position at the time of several communications exchanges which include the aircraft's altitude at the approximate time of communication. At 1144:12, Seattle ARTCC advised Seattle Approach control of N3674P's position near Bandera, 35 miles out of Seattle. Seattle Approach established radar contact at 1144:31. At 1145:01, N3674P, which had been handed off to Seattle Approach from Seattle ARTCC, came up on frequency with Seattle Approach. At 1145:07, the pilot stated that his altitude was 10,500 and descending, and moments later advised that he was going down "about fifteen hundred per minute." (See "B" on depiction.) At 1145:55, the pilot stated "...let go ah negative oil pressure for seven four papa," and--a few seconds later--acknowledged that he had completely lost his engine. At 1146:48, Seattle Approach advised N3674P of Enumclaw airport at eleven o'clock and 15 miles, and Bandera airport, about ten miles north, but advised of 5400 feet terrain north of his position. At 1147:01, the pilot said that he would "go for Enumclaw." At 1148:02, N3674P's altitude was 7500 feet. (See "C" on depiction.) At 1148:40, the pilot stated that his altitude was 6200 feet ("D" on depiction). At 1150:31, the pilot stated "and there goes the power." His altitude was 4500 feet at 1150:39 ("E" on depiction). At 1151:55, Seattle Approach provided a suggested heading of 260 for Black Diamond. The pilot noted that he had a hill ahead on that heading. At 1152:13, his altitude was 3100 feet ("F" on depiction). Seattle Approach asked if any roads were visible, and suggested that the pilot try for one if he was unable to glide to an airstrip. At 1153:17, the pilot stated "seven four papa's one thousand seven hundred ["G" on depiction]. I'm going to try this road over here." At 1153:48, there was an unintelligible communication to Seattle Approach. There were no further direct communications with Seattle Approach from N3674P. At 1154:48, another aircraft in the vicinity advised Seattle Approach that N3674P's pilot made a last transmission saying that "he...wasn't gonna make the road and he was going to...go down in the trees." Witnesses fishing near the Green River Headworks control gate saw the airplane and heard what sounded like engine problems. They then saw the aircraft make a course reversal eastbound and then crash and burn on the north side of the river. The wreckage was found about 6 miles east of Black Diamond, Washington, in a willow or aspen grove at "G" on the attached depiction. According to a GPS receiver, approximate latitude and longitude of the accident site was N 48 degrees 18.5 minutes and W 121 degrees 51 minutes, about 800 feet above sea level. The wreckage was on the opposite side of the shoreline from the SE Green River Headworks access road to the Howard Hansen Reservoir, about 2 miles east of the intersection of Cumberland-Kanaskat RD SE and the SE Green River Headworks roads. When the wreckage site was overflown by investigators, it was noted that an abandoned airstrip, of approximately 1500-2000 feet length and marked with white "X"s, was on the opposite side of the river, within about a mile of the crash site. AIRCRAFT INFORMATION The aircraft had undergone an annual inspection March 1, 1995. Since that date, it had accumulated approximately 290 hours flight time, and the engine had approximately 900 hours since factory remanufacture. The engine had been installed about January or February of 1993. In July of 1995, six overhauled cylinders from ECI were installed, which had approximately 120 hours since installation at the time of the accident. Pilots had observed that the oil pressure had dropped on at least three occasions, but that it had remained in the green oil pressure range. Each time, oil screens were checked and no metal was found. The aircraft was not consuming oil. During the 30 days preceding the accident, the oil relief check valve had been checked for condition, the oil cooler thermal control valve had been replaced, and at least two oil filters had been opened and checked for contamination. On the Saturday previous to the accident, the oil pressure was reported to have been back up to the expected range. The aircraft had 16.5 gallon auxiliary fuel tanks installed in the outboard portions of the wings. WRECKAGE AND IMPACT INFORMATION Terrain in the vicinity of the accident was hilly or mountainous, and heavily forested, in brush or willowy growth, near the riverbed. Broken limbs in trees, about 20 feet above the surface, were noted about 39 feet to the west of the left hand wing tip. The propeller was about 15 feet east of the left wing tip. A crater was about eighteen feet east and ten feet south of the propeller. The main wreckage was southeast of the crater, with its remaining fuselage oriented on a centerline of about 125 degrees, nose to tail. The wreckage sustained extensive fire damage. The right wing was extensively melted in the fuel tank area near the root, and at the wing tip area, where the auxiliary tank was installed. The left wing also had extensive impact and fire damage. The wing flaps were determined to have been in the extended position. The main fuselage area was mostly consumed by fire. The instrument panel was burned away, and the remaining instruments and radios provided no usable information. The tachometer was found and the rpm indication was off scale at the 6 'clock position. The throttle was in idle position; the mixture was in rich position, and the propeller control was full forward. A large camera was mounted where the pilot's seat is normally located. The copilot's seat was installed. A large oxygen bottle was installed behind the copilot's seat. The engine remained attached to the firewall. The cowling remained attached, and was partially consumed by fire. The cowling was removed for inspection. The throttle butterfly was at idle; the mixture control was in a mid-range position, and the propeller lever was at full aft position. The top of the engine and accessory section exhibited fire damage. The left magneto was separated from its mount. Three holes were noted in the crankcase, with one above cylinder #4, with the connecting rod visible; one above cylinder #3; and another under the left magneto above cylinder #2. Many of the tubes, hoses and wires forward of the firewall were consumed by fire or broken. The starter and alternator exhibited partial melting. The empennage exhibited some burning near the fuselage. The rudder was displaced to the left about 20 degrees. The elevator was approximately in trail, with the right elevator trim tab bent upward about 45 degrees. The empennage was inspected for indications of fresh oil, but none were noted. The propeller spinner exhibited crushing and some compression around the propeller hub. The three blades exhibited little leading-edge deformation. One blade exhibited longitudinal bending aftward in a large arc, with extensive cross-blade scratching and scoring. The propeller had separated from the engine at the crankshaft flange. TESTS AND RESEARCH The engine was shipped to the Teledyne Continental factory in Mobile, Alabama, for disassembly and inspection. During the course of the disassembly it was noted that the crankcase main bearings and crankshaft main journals exhibited oil starvation. Four connecting rods (cylinders 1, 2, 3, 4) were separated with thermal stretching and breaking of their rod bolts. The two remaining rods (cylinders 5, 6) were removed. Their rod bearings were partially melted and extruded. Details describing internal damage consistent with oil starvation are in the attached report. A B-nut, which had been tagged as loose by the salvage organization that shipped the engine to Mobile, was found to be 1 1/2 flats (of the hex nut) loose. The B-nut and associated tubing were removed and shipped to the NTSB Materials lab for testing. The NTSB Materials lab examined the B-nut and the end of the oil inlet supply line. According to that examination, "approximately three threads in the area where the oil line end is assembled were truncated, apparently during the manufacturing process. Major portions of the threads were covered by what appeared to be a deposit of aluminum, with some bright droplets." The exhaust-driven turbocharger, an Allied Signal model THO8A69, serial number VJR1007, was subjected to teardown and inspection. The teardown and examination of the turbocharger disclosed that it was functional at the time of impact. That report is attached. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by Dr. Richard C. Harruff, King County Associate Medical Examiner, on September 11, 1995 at Seattle, WA. Toxicological testing was performed by the FAA toxicology lab. Results include 15% carboxyhemoglobin and 1.420 cyanide detected in blood, and quinine, but no ethanol detected in urine. ADDITIONAL INFORMATION The wreckage was released January 23, 1996, to James V. Stiger, insurance adjuster for the owner, where it was in storage at Boeing Field, Seattle, Washington.
improper maintenance which led to oil starvation due to a inadequately tightened B-nut in an oil line. A factor was the lack of suitable terrain for a forced landing.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
