Portland, OR, USA
N6352Y
Cessna 170B
The airplane was returning to its home airport when the pilot became incapacitated by carbon monoxide fumes from the airplanes engine muffler heat exchanger [the heat control knob was found "On"]. During the last 15 minutes of flight, the radar data shows the airplane flying several meandering 360 degree turns before impacting terrain. Postimpact examination of the engine's muffler revealed a crack around the entire circumference just aft of it's forward flange. The airplane's last annual inspection was completed on February 1, 2005. The FAA, in Federal Aviation Regulation, Part 43: Maintenance, Preventive maintenance, Rebuilding, and Alteration, Appendix D, provides guidelines for an airplane's annual inspection. Section (d) (8) Exhaust stacks--for cracks, defects, and improper attachment. The airplane's manufacturer also provides a checklist for an annual inspection in the aircraft's Service Manual. In the section for the Engine Compartment, #12. Exhaust system for security, leaks, cracks, and burned-out spots. Refer to Paragraph 12-74 [Inspection of the exhaust system].
HISTORY OF FLIGHT On April 30, 2005, at 2011 Pacific daylight time, a Cessna 170B, N6352Y, was destroyed when it impacted terrain near Portland, Oregon. The private pilot, the sole person on board, was fatally injured. The airplane was being operated under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the personal, cross-country flight that originated from Spangle, Washington, at approximately 1700. A flight plan had not been filed. Friends of the pilot stated that he had departed Pearson Field (VUO), Vancouver, Washington, at approximately 0755 on the morning of the accident to attend a high school reunion at Spangle, Washington. On his return flight, he had stopped at Pullman/Moscow Regional Airport (PUW), Pullman, Washington, and purchased 26.2 gallons of fuel [the airplane had a 21 gallon tank in each wing; the service personnel at Pullman said that both fuel tanks were "topped off."] Federal Aviation Administration (FAA) radar data, from Portland International Airport, Portland, Oregon, first identified the airplane at 1900:04, at 6,500 feet, approximately 8 nautical miles (nm) north of Hood River, Oregon. The radar data indicates that the airplane flew parallel to the Columbia River towards Battle Ground VOR, but at the county line between Skamania and Clark counties, the airplane began to veer north towards Woodland, Washington. At 1956:01, the airplane was headed south towards Pearson Airpark at 2,600 feet. For the next 15 minutes, the airplane completed several meandering 360 degree turns and progressed south towards the Columbia River. The last radar return was at 2011:20, at 100 feet, very near to where the wreckage was found. Several witnesses heard the airplane's engine just before impact, and their statements varied from "the engine sounded fine to me," to "the engine did not sound good," to "the engine of the plane [was] running, but it was 'sputtering'." A witness, who was playing golf nearby, said that between 2010 and 2020 he heard a "very loud impact," but did not see the crash. The golfers drove in the direction of the sound and discovered the wreckage approximately 30 minutes later. PERSONAL INFORMATION The pilot's most recent Federal Aviation Administration (FAA) flight medical exam (third class) was on March 29, 2005. His flight logbook indicates that he had 338 hours of flight experience since May 1985. He was also a certificated airframe and power plant mechanic. His last FAA required flight review was on March 16, 2005. AIRCRAFT INFORMATION The airplane was a single engine, propeller-driven, four seat airplane, which was manufactured by Cessna Aircraft Company, in 1953. The airplane had a maximum takeoff gross weight of 2,200 pounds. It was powered by a Continental C 145-2, six cylinder, reciprocating, horizontally opposed, direct drive, air cooled, normally aspirated engine, which had a maximum takeoff rating of 145 horsepower at sea level. Maintenance records indicate that the last annual inspection was completed on February 1, 2005. The airplane's engine tachometer and maintenance records indicated that the airframe had 5,371 hours on it at the time of the accident. METEOROLOGICAL INFORMATION At 1955, the weather conditions at Portland International Airport (elevation 30 feet), Portland, Oregon, 060 degrees for 5 nautical miles from the accident site, were as follows: wind 320 degrees at 5 knots; visibility 10 statue miles; few clouds at 5,000 feet; temperature 17 degrees Celsius; dew point 10 degrees Celsius; altimeter setting 30.04 inches. Sunset at Portland, Oregon, on April 30, 2005, was 2017. WRECKAGE IMPACT INFORMATION The airplane was found on the west side of a steep down-sloping railroad grade (N45 degrees, 36', 10.3"; W122 degrees, 42', 56.2''; elevation 22 feet) in a 5 foot high, very thick brier patch. All of the airplane’s major components were accounted for at the accident site. Approximately 6 feet of the left wing's outboard tip had been separated from the airplane and was located approximately 150 feet east of the main wreckage in a tree approximately 45 feet above the ground. The remainder of the left wing was structurally broken from the fuselage, and remained connected by wires and cables. Halfway between the left wing tip and the fuselage were two entry doors, and a few feet further west was the outboard half of the right wing. The fuselage was nearly vertical and slightly on its left side. The engine module with cockpit instrumentation and controls (including flight control yokes and rudder peddles) had separated from the fuselage/cabin at the forward door posts. The main landing gear were in place, but structurally broken from the fuselage. The empennage was completely separated from the fuselage, but some of the flight control cables were still intact. The flaps were found in their up position. During the wreckage review, the engine's crankshaft was rotated, and valve train continuity was observed at all cylinders; rotational continuity was also observed at the magnetos. No preimpact engine or airframe anomalies, which might have affected the airplane's performance, were identified. One propeller blade had its outboard 4 to 5 inches bent 10 to 20 degrees forward. The second blade had the outboard half bent aft approximately 120 degrees and exhibited some "S" type bending. There was evidence of chord wise striations on both blades. The cabin heat control was "On." Exhaust residue was present on the forward side of the firewall above and below the firewall mounted heater valve. The inside of the heater hose had exhaust residue. The left muffler shroud was removed and the muffler was found cracked around its entire circumference just aft of it's forward flange. MEDICAL AND PATHOLOGICAL INFORMATION The Oregon State Medical Examiner, Clackamas, Oregon, performed an autopsy on the pilot on May 1, 2005. They determined that the cause of dearth was carbon monoxide toxicity (Hypemic Hypoxia) and positional asphyxia. The coroner said that he found the pilot suspended by his seat belt, which transversed the pilot at his solar plexus. The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report (#200500095001), the pilot's blood and urine were tested for cyanide, volatiles (ethanol), and drugs with negative results; however, his blood contained 50 percent carbon monoxide. ADDITIONAL INFORMATION The FAA, in Federal Aviation Regulation, Part 43: Maintenance, Preventive maintenance, Rebuilding, and Alteration, Appendix D, provides guidelines for an airplane's annual inspection. Section (d) (8) Exhaust stacks--for cracks, defects, and improper attachment. The airplane's manufacturer also provides a checklist for an annual inspection in its Service Manual for the aircraft. In the section for the Engine Compartment, #12. Exhaust system for security, leaks, cracks, and burned-out spots. Refer to Paragraph 12-74 [Inspection of the exhaust system]. The airplane, including all components and logbooks, was released to a representative of the owner’s insurance company, on May 23, 2005.
The pilot's inability to control the airplane due to his incapacitation (carbon monoxide poisoning) from a deteriorated engine exhaust muffler. A contributing factor was the inadequate annual inspection by other maintenance personnel.
Source: NTSB Aviation Accident Database
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