CEN17FA332

The private pilot was flying the airplane at a low altitude when the engine lost total power. The pilot reported that the engine did not sputter, bang, or run roughly before the loss of engine power; however, several witnesses heard the airplane's engine running roughly immediately before the crash. One witness reported that the airplane's engine fluctuated between "sputtering" and "revving" before it lost total power. The airplane collided with trees and terrain during the subsequent forced landing and came to rest inverted. Postaccident examination of the airplane and engine did not reveal any evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Additionally, the airplane had ample fuel available that did not contain any water or debris. The engine also demonstrated the ability to produce rated horsepower during a postaccident operational test run. The carburetor heat control was in the "OFF" position. The weather conditions at the time of the accident were conducive to moderate carburetor icing at cruise power and serious carburetor icing at descent power. The pilot reported that he did not use carburetor heat during the flight because he was operating the engine at a cruise power setting. The airplane flight manual states that carburetor heat should be used upon a loss of engine power or an unexplained decrease of manifold pressure, a roughly running engine, or before the throttle is moved to idle for landing. Additionally, the use of carburetor heat might be required to avoid carburetor ice accumulation during a descent at a reduced engine power setting. According to a Federal Aviation Administration Special Airworthiness Information Bulletin, pilots should use carburetor heat while in weather conditions where carburetor icing is probable. Based on the available information, the total loss of engine power was likely due to carburetor ice accumulation. Additionally, the low altitude at which the loss of engine power occurred precluded the pilot from reestablishing normal engine operation before the airplane descended into trees.

The 1973-model-year airplane, serial number 18052344, was a high-wing monoplane of aluminum semi-monocoque construction. The airplane was powered by a 235-horsepower, 6-cylinder, reciprocating engine. The engine was originally manufactured as a Continental IO-520-D23A, serial number 552352; however, the engine was subsequently converted to an P. Ponk Aviation O-470-50, serial number 2518, after being modified by Supplemental Type Certificate No. SE4988NM. The engine provided thrust through a constant-speed, two-blade, McCauley D2A34C58-NO propeller, serial number 760467. The airplane was equipped with landing floats, wing flaps, and had a maximum gross weight of 3,100 pounds. The FAA issued the airplane a standard airworthiness certificate on May 29, 1973. The airplane's recording tachometer indicated 3,951.42 hours at the accident site. The pilot provided excerpts of the maintenance logbooks, which indicated that the last annual inspection of the airplane was completed on June 30, 2016, at 3,954 total airframe hours. At the last annual inspection, the engine had accumulated 109.44 hours since its most recent overhaul. There were no maintenance entries after the June 2016 annual inspection. The airplane flight manual states that carburetor heat should be used upon a loss of engine power or an unexplained decrease of manifold pressure, a rough running engine, or before the throttle is moved to idle for landing. Additionally, the use of carburetor heat might be required to avoid carburetor ice accumulation during a descent at a reduced engine power setting. The airplane's instrument panel was equipped with a carburetor air temperature gauge that was wired to a thermocouple installed at the carburetor inlet. On August 28, 2017, about 1312 eastern daylight time, a float-equipped Cessna 180J airplane, N180LP, impacted trees and terrain during a forced landing near Gaylord, Michigan. The private pilot and his passenger were seriously injured, and the airplane sustained substantial damage. The airplane was registered to the pilot and was operated under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. Day visual meteorological conditions prevailed for the local flight that departed Otsego Lake, Michigan, about 1250. The pilot reported that after departing Otsego Lake he flew north toward the Gaylord Regional Airport (GLR) to conduct a practice instrument landing system approach to runway 9. After the practice approach, he flew toward his private airstrip located about 5 miles southeast of GLR. He reported that the airplane experienced a total loss of engine power and the propeller stopped rotating as he was conducting a series of turns near his airstrip. The pilot stated that before the loss of engine power the airplane was at least 500 ft above ground level (agl) and the engine was operating at 2,300 rpm and 23 inches of manifold pressure. Additionally, he stated that the engine did not sputter, bang, or runrough before the loss of engine power. The pilot reported that the airplane collided with trees during the forced landing. When asked how much fuel was onboard before the flight, the pilot estimated that the main fuel tanks contained about 45 gallons total, and that both 17-gallon auxiliary fuel tanks were completely full. Additionally, the pilot stated that he does not operate the engine with carburetor heat engaged above 17 inches of manifold pressure. The passenger reported that they circled the pilot's private airstrip a couple of times to view the property. While circling over the airstrip, the pilot and passenger observed and discussed how the fuel gauges fluctuated while the airplane was in a sustained turn with partially full fuel tanks. The passenger reported that the engine quit while the airplane was in a turn, and that the airplane collided with trees as the pilot attempted to land at the airstrip. The passenger stated that the airplane came to rest inverted, and that a first responder assisted him in getting out of the airplane. There were no eyewitness to the accident; however, there were numerous individuals who had heard the airplane's engine running rough immediately before the crash. One witness reported the airplane's engine fluctuated between "sputtering" and "revving" before it lost total power. A postaccident review of available meteorological data established that day visual meteorological conditions prevailed at the accident site. The nearest aviation weather reporting station was located at GLR about 5 miles northwest of the accident site. At 1253, about 19 minutes before the accident, the GLR automated surface observing system reported a variable wind direction at 4 knots, 10 miles surface visibility, a broken ceiling at 1,700 ft agl, an overcast ceiling at 9,000 ft agl, temperature 18°C, dew point 14°C, and an altimeter setting of 30.13 inches of mercury. According to a carburetor icing probability chart contained in FAA Special Airworthiness Information Bulletin CE-09-35, entitled "Carburetor Icing Prevention", the recorded temperature and dew point were in the range of susceptibility for the formation of carburetor icing. The bulletin notes that if ice forms in the carburetor of a constant-speed propeller aircraft, the restriction to the induction airflow will result in a drop of manifold pressure, a reduction in engine horsepower, and often roughness in engine operation. Additionally, according to the bulletin, a pilot should use carburetor heat when operating the engine at low power settings, or while in weather conditions where carburetor icing is probable. According to a carburetor icing-probability chart published by the Australian Transport Safety Bureau, the weather conditions at the time of the accident were conducive to serious icing at descent power and moderate icing at cruise power. According to Federal Aviation Administration (FAA) records, the 77-year-old pilot held a private pilot certificate withratings for airplane single-engine land and sea, airplane multiengine land, instrument airplane, and rotorcraft-helicopter. His last aviation medical examination was on March 10, 2017, when he was issued a third-class medical certificate with no limitations. A pilot logbook was not reviewed during the investigation. The pilot reported that he had accumulated about 5,500 total hours of flight experience, of which 3,000 hours were flown in single-engine land airplanes, 1,000 hours in single-engine seaplanes, 1,000 hours in multi-engine land airplanes, and 500 hours in rotorcraft. The pilot had flown about 1,000 hours in instrument conditions and about 800 hours at night. The pilot reported having flown about 100 hours and 50 hours during the 90 days and 30 days before the accident, respectively. The accident flight was about 22 minutes and was the only flight completed within 24 hours of the accident. The pilot reported that his most recent flight review, as required by Title 14 CFR 61.56, was completed on October 10, 2015. The engine was sent to the manufacturer for an operational test run. The engine was installed in a test cell and outfitted with a test club propeller. The engine started on the first attempt and operated normally at idle without excessive fluctuations in engine rpm. The engine speed was then increased incrementally to full throttle (2,660 rpm and 26.67 inches of manifold pressure) over a period of 25 minutes. After achieving maximum power, the throttle was cycled several times between idle and maximum power in quick succession with no interruption or hesitation in power production. There was no hesitation, stumbling, or interruption in engine operation observed during the test run. The engine demonstrated the ability to produce rated horsepower during the operational test run. An on-scene investigation revealed that the airplane initially collided with a 50 ft tall white pine tree, followed by a 30 ft tall birch tree, and came to rest inverted about 155 ft from the initial tree impact. The wreckage debris path was on a northeast heading. There were at least two branches that exhibited flat cuts and black paint transfer that were consistent with a propeller strike. Flight control cable continuity was confirmed from the cockpit controls to the individual flight control surfaces. The wing flaps were found fully retracted. The engine throttle control was out about 1.5 inches, the propeller control was out about 1/2 inch, and the mixture control was in the full rich position. The carburetor heat control was in the "OFF" position. The water rudders were in the stowed position. With the airplane still inverted, about 3/4 cup of fuel was drained from the supply line between the fuel flow transducer and the carburetor. The recovered fuel was blue in color and free of any contamination. Additionally, the fuel strainer assembly leaked fuel as it was opened. The fuel strainer screen was clear of debris. The inverted carburetor was removedfrom the engine and its accelerator pump discharged fuel when actuated. The carburetor fuel bowl contained several ounces of fuel. No anomalies were observed with the carburetor floats, needle valve, venturi, or inlet fuel screen. When the airplane was recovered to an upright position, fuel was observed to drain from the fractured fuel lines located in the aft door posts. Recovered fuel samples were blue in color and free of any contamination. The fuel selector was found in the "BOTH" position, and a functional test revealed no anomalies. The airplane was equipped with an electronic fuel flow indicator, which displayed 69.2 gallons remaining and that 24.8 gallons had been used since the device was last reset. The electronic fuel flow indicator was configured to use 60 gallons for the combined capacity of the main fuel tanks and 34 gallons for the auxiliary tanks, for a total fuel capacity of 94 gallons. The engine remained partially attached to the firewall by control cables, electrical wires, and oil lines. Mechanical continuity was confirmed from the engine components to their respective cockpit engine controls. Internal engine and valve train continuity was confirmed as the engine crankshaft was rotated. Compression and suction were noted on all cylinders in conjunction with crankshaft rotation. A boroscope inspection did not reveal any anomalies with the cylinders, pistons, valves, or valve seats. The spark plugs were removed and exhibited features consistent with normal engine operation. Both magnetos provided spark on all leads when rotated. There were no obstructions between the air filter housing and the carburetor. The two-blade constant speed propeller remained attached to the crankshaft flange. The propeller exhibited minor burnishing on the cambered-side of both blades. One blade appeared straight. The other propeller blade exhibited a slight twist toward low pitch near the blade tip, and the blade tip was bent slightly forward. The postaccident examination revealed no evidence of a mechanical malfunction or failure that would have precluded normal engine operation.