WPR23LA156

The pilot completed the airplane’s engine run-up and carburetor heat function checks with no anomalies noted. He then taxied to the runway and experienced an extended ground delay with the engine running at idle engine power settings. He did not use carburetor heat during the ground delay or during takeoff. About 1,000 ft above ground level (agl), during the initial climb, the engine lost all power. The pilot initiated a forced landing to a field ahead of the airplane’s position and subsequently struck terrain. Postaccident examination of the engine revealed no evidence of mechanical malfunction or failure that would have precluded normal operation. The weather conditions at the time of the accident were conducive to the formation of serious carburetor icing at glide (idle) engine power settings. It is likely that during the post run-up taxi and ground delay, a period during which the engine would typically be operating at low or idle power settings, carburetor ice formed that resulted in a total loss of engine power during the initial climb.

On April 16, 2023, about 1010 Pacific daylight time, a Piper PA-28-180, N8376W, was substantially damaged when it was involved in an accident near Riverside, California. The pilot and one passenger were not injured. The second passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, after conducting engine run-up and carburetor heat function checks, he switched to the left fuel tank, then taxied for departure. After taxiing to runway 27 at the Riverside Municipal Airport (RAL), Riverside, California, he “had to wait a while” before being issued a takeoff clearance from air traffic control. After takeoff and during the initial climb, about 1,000 ft agl, the engine “sputtered and came back.” The pilot verified that the mixture was full rich, the fuel pump was on, the left fuel tank was selected, and that the magneto switch was on both. Shortly thereafter, the engine sputtered a second time, then lost total power. The pilot initiated a forced landing to a nearby field ahead of the airplane’s position. During the off-airport landing, the airplane struck terrain and came to rest upright about 2 miles west of the departure end of runway 27. Postaccident examination of the engine revealed that when the crankshaft was rotated by hand using the propeller continuity was established throughout the engine and valvetrain. Thumb compression was obtained on all cylinders. An alternate fuel source was plumbed to the right-wing fuel inlet port and the engine was run. The fuel source was removed and reattached to the left-wing fuel inlet port and the engine was run. At 0953, the weather reported at RAL, included a temperature of 16°C and a dewpoint of 9°C. The calculated relative humidity at this temperature and dewpoint is approximately 65%. Review of the icing probability chart contained in Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin CE-09-35 revealed that the weather conditions at the time of the accident were “conducive to serious icing at glide [idle] power.” According to FAA Advisory Circular 20-113, “To prevent accidents due to induction system icing, the pilot should regularly use [carburetor] heat under conditions known to be conducive to atmospheric icing and be alert at all times for indications of icing in the fuel system.” The circular recommended that when operating in conditions where the relative humidity is greater than 50%, “…apply carburetor heat briefly before takeoff, particularly with float type carburetors, to remove any ice which may have been accumulated during taxi and runup.” It also stated, “Remain alert for indications of induction system icing during takeoff and climb-out, especially when the relative humidity is above 50%, or when visible moisture is present in the atmosphere.”