NTSB Factual Report

On September 27, 2015, about 0946 mountain daylight time, a Cessna 182G airplane, 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 airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed about the time of the accident, and the flight was not operating on a flight plan. The local flight originated from the Aspen-Pitkin County Airport/Sardy Field (ASE), near Aspen, Colorado, about 0929.

According to the pilot's accident report, he performed a preflight inspection of the airplane and listened to a recorded weather report at ASE. He performed an engine run-up and took off to the northwest. The pilot reported that about 15 minutes later, he was at 9,700 feet above mean sea level and he realized he was at full throttle and had no more power to climb. He said that the engine monitor indicated he "lost cylinder #2 and #4 was going down." He stated that the engine did not stop but it was "running very low." The pilot thought of diverting to an airport but did not have enough altitude. He spotted an open field near Highway 82 south of Glenwood Springs and he flew the airplane to it. The pilot heard the stall warning horn sound and he turned the airplane left to the south to land uphill. He knew the field was not flat. The airplane touched down twice, it impacted a ditch, and it nosed over.

The pilot held a Federal Aviation Administration (FAA) private certificate with an airplane single-engine land rating. The pilot was issued an FAA third class medical certificate, on August 11, 2015, with a limitation to have glasses available for near vision. According to the pilot's report, he accumulated 640 hours of total flight time.

N3147S was a 1964 model Cessna 182G, single-engine, high-wing, fixed tricycle landing gear airplane with serial number 18255647. The airplane was powered by a six-cylinder, 230 horsepower Continental O-470-R reciprocating engine, marked with serial number 130470-4-R. The engine drove a McCauley two-bladed constant speed propeller. The operator reported that the airplane had accumulated 5,593 hours of total flight time. According to the airplane's maintenance records, an endorsement indicated that the last annual inspection was completed on April 30, 2015 and a tachometer time of 4,181 hours was noted. The endorsement indicated that the magneto 500-hour check was accomplished and their timing was set to 22 degrees before top dead center when the magnetos were reinstalled.

The accident airplane was equipped with a J. P. Instruments (JPI) EDM-700, which was a panel-mounted gauge that the operator can monitor and record up to 24 parameters related to engine operations. Depending on the installation engine parameters monitored can include Exhaust Gas Temperature (EGT), Cylinder Head Temperature (CHT), Oil Pressure and Temperature, Manifold Pressure, Outside Air Temperature, Turbine inlet Temperature, Engine Revolutions per Minute, Compressor Discharge Temperature, Fuel Flow, Carburetor Temperature, and Battery Voltage. The unit can also calculate, in real-time, horsepower, fuel used, shock cooling rate and EGT differentials between the highest and lowest cylinder temperatures. The calculations are also based on the aircraft installation.

The unit contains non-volatile memory for data storage of the parameters recorded and calculated. The rate at which the data is stored is selectable by the operator from 2 to 500 seconds per sample. The memory can store up to 20 hours of data at a 6-second sample rate.

The airplane was also equipped with a Horizon Instruments P-1000, which was a digital tachometer which provides diagnostic and performance information about the aircraft's engine and ignition system. The system provides a means to electronically monitor engine rpm in a digital representation. The device also records aircraft engine hours. The device can store engine hour information and highest RPM achieved during a power cycle.

At 0950, the recorded weather at the Eagle County Regional Airport (EGE), near Eagle, Colorado, was: Wind calm; visibility 10 statute miles; sky condition clear; temperature 8 degrees C; dew point -2 degrees C; altimeter 30.30 inches of mercury.

The temperature and dew point were plotted on a carburetor icing probability chart. The intersection of the temperature and dew point crossed in a range favorable for the formation of carburetor icing at glide and cruise power.

Inspectors from the FAA, and technical representatives from the airframe and engine manufacturer examined the airplane wreckage when it was recovered to a recovery company's yard. All major components of the airplane were accounted for at the yard and the recovery company reported that about 50 gallons of fuel was recovered from the airplane. The examination of the engine and airframe did not reveal any pre-impact mechanical anomalies, nor was a reason for the loss of engine power found.

The JPI EDM-700, Horizon Instruments P-1000, and the engine were separated from the wreckage. The engine was shipped to its manufacturer for further testing and the EDM-700 and the Horizon Instruments P-1000 were shipped to the NTSB Recorder Laboratory for examination, downloading, and decoding.

According the vehicle recorder specialists report, the P-1000 device arrived in working condition. Power was applied to the instrument in the laboratory as per the manufacturer's installation manual, the device powered normally. The digital tachometer reported a total engine time of 4,194 hours.

The JPI EDM-700 recorder arrived in good condition and its data was extracted normally. The data indicated that all recorded values appear nominal during the early portion of flight. About 0923, the indicated carburetor air temperature value began falling from 69 degrees F to around 42 degrees F. within a span of about 30 seconds. The carburetor air temperature values do not subsequently increase to above 45 degrees F until the last recorded data point. About 0933, values for EGT on cylinder 1 began dropping. Around the same time, the engine monitor reported that shock cooling rate began to increase to around -43 degrees F per minute. Values for fuel flow dropped slightly. CHT for all cylinders begin trending downward. About 0936, values for EGT on cylinder 3 began falling as compared to the other four remaining cylinders. About 0938, cylinder 1 and 3's EGT values had steadied between 350 and 450 degrees F. CHTs for cylinders 1 and 3 continued to drop in comparison to the other 4 remaining cylinders. The recording ended at 0946 showing signs that remaining engine power was dwindling.

The National Transportation Safety Board Investigator-In-Charge (IIC), oversaw an engine examination and engine run at Continental Motors, near Mobile, Alabama. A section of the carburetor's mounting flange separated from the carburetor. It was repaired and remounted to its intake. The oil pan and cross over tube were impact damage and were replaced with exemplar parts. The exhaust muffler was examined and no internal or external anomalies were detected. A test club propeller was mounted to the engine and the engine was mounted to a test stand. The engine was operational during a test run.

The pilot stated that "I know I can't use [carburetor] heat when climbing." However, the airplane owner's manual, in part, stated:

To operate the engine without a winterization kit in occasional outside

air temperatures from 10 [degrees] to 20 [degrees] F, the following

procedure is recommended:

(1) Use full carburetor heat during engine warm-up and ground check.

(2) Use minimum carburetor heat required for smooth operation in

take-off, climb, and cruise.

(3) Select relatively high manifold pressure and RPM settings for

optimum mixture distribution, and avoid excessive manual leaning in

cruising flight.

(4) Avoid sudden throttle movements during ground and flight operation.

When operating in sub-zero temperatures, avoid using partial

carburetor heat. Partial heat may raise the carburetor air temperature

to the 32 [degree] to 80 [degree] range where icing is critical under certain

atmospheric conditions.

NTSB Probable Cause

A loss of engine power during cruise flight due to carburetor icing and the pilot's failure to apply carburetor heat, which resulted in a forced landing on rough/uneven terrain.