Accident Overview
On September 27, 2015, about 0946 mountain daylight time, a Cessna 182G (registration N3147S) impacted rough terrain during a forced landing near Glenwood Springs, Colorado. The private pilot was seriously injured and the passenger received minor injuries. The airplane sustained substantial wing and fuselage damage. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight, originating from Aspen-Pitkin County Airport/Sardy Field (ASE) about 0929. Day visual meteorological conditions prevailed; no flight plan was filed.
Pilot Information
The pilot held a Federal Aviation Administration (FAA) private certificate with an airplane single-engine land rating and a third-class medical certificate issued August 11, 2015, with a limitation for near vision glasses. He reported 640 hours of total flight time.
Aircraft Information
N3147S was a 1964 Cessna 182G, a single-engine, high-wing, fixed tricycle landing gear airplane (serial number 18255647). It was powered by a Continental O-470-R six-cylinder, 230 horsepower engine (serial number 130470-4-R) driving a McCauley two-bladed constant speed propeller. Total airframe time was 5,593 hours. The last annual inspection was completed on April 30, 2015, at a tachometer time of 4,181 hours. The magneto 500-hour check was accomplished and timing set to 22 degrees before top dead center.
The aircraft was equipped with a J.P. Instruments EDM-700 engine monitor (recording parameters such as exhaust gas temperature (EGT), cylinder head temperature (CHT), and carburetor air temperature) and a Horizon Instruments P-1000 digital tachometer.
Accident Sequence
According to the pilot's report, he performed a preflight inspection and listened to the recorded weather at ASE. After an engine run-up, he took off to the northwest. About 15 minutes later, at 9,700 feet mean sea level, he realized he was at full throttle with no further climb power. The engine monitor indicated a loss of cylinders #2 and #4. The engine continued running but at very low power. Unable to reach an airport, he spotted an open field near Highway 82, south of Glenwood Springs. He heard the stall warning horn, turned left to land uphill, and the airplane touched down twice, impacted a ditch, and nosed over.
Weather Conditions
At 0950, the recorded weather at Eagle County Regional Airport (EGE) was: wind calm, visibility 10 statute miles, sky clear, temperature 8°C, dew point -2°C, altimeter 30.30 inHg. Plotting temperature and dew point on a carburetor icing probability chart indicated conditions favorable for carburetor icing at glide and cruise power.
Post-Accident Examination
Inspectors from the FAA and technical representatives examined the wreckage at a recovery facility. About 50 gallons of fuel were recovered. Examination of the engine and airframe found no pre-impact mechanical anomalies; the reason for the loss of engine power was not determined. The engine, EDM-700, and P-1000 were sent for further analysis.
The P-1000 arrived in working condition and read 4,194 engine hours. The EDM-700 data extraction showed nominal values early in flight. About 0923, carburetor air temperature dropped from 69°F to about 42°F over 30 seconds and remained below 45°F until the end. Around 0933, EGT on cylinder 1 began dropping, and the shock cooling rate increased to about -43°F per minute. Fuel flow dropped slightly, and CHT for all cylinders trended downward. By 0936, EGT on cylinder 3 also fell. The recording ended at 0946, indicating dwindling engine power.
The engine was examined and run at Continental Motors. The carburetor mounting flange was repaired and the oil pan and crossover tube replaced due to impact damage. The exhaust muffler had no anomalies. A test club propeller was mounted, and the engine operated successfully on a test stand.
The pilot stated he knew not to use carburetor heat when climbing. However, the airplane owner's manual recommends using full carburetor heat during warm-up and ground check, and minimum carburetor heat for smooth operation in takeoff, climb, and cruise. In sub-zero temperatures, partial heat should be avoided as it may raise carburetor air temperature into the critical icing range (32°F to 80°F).