N2728BCessna 182B · 1959

On August 28, 2024, about 1050 Hawaii-Aleutian Standard time (HST), a Cessna 182B airplane, N2728B, sustained substantial damage when it was involved in an accident near Hawi, Hawaii. The pilot sustained minor injury. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 skydiving flight.

The pilot reported that, after dropping skydivers, he began a spiraling descent from 8,500 ft mean sea level (msl) to return to the Upolo Airport (PHUP) in Hawi, Hawaii. The pilot said he reduced the throttle to idle, added 20° of flaps, and after a few seconds, applied full carburetor heat and slowly increased the engine mixture. As the airplane descended to an altitude of about 300 ft agl (Above Ground Level), he confirmed the mixture was full rich, the propeller was full forward, and the carburetor heat was full on. As he increased the throttle, the engine did not respond, he completed steps to troubleshoot the loss of power, however power was not established. The pilot made a forced landing in a field about a mile west of the airport; the airplane encountered uneven terrain and the nose gear collapsed, resulting in substantial damage to the fuselage and engine compartment.

A postaccident examination of the engine and fuel system revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The gascolator contained 100LL aviation fuel and when fuel was sumped from the airplane’s tanks only a trace amount of water was present.

The closest official weather reporting station to the accident location was at Upolu Airport (PHUP), Hawi, Hawaii, located about ¼ mile east of the accident site at an elevation of 107 ft. The airport had a non-official automated weather observing system that did not issue any long-term observations. A weather observation recorded at Kailua/Kona Keahole Airport (PHKO), located about 34 miles south at 1053 HST listed the temperature of 84°F and the dew point of 71°F. The Carburetor Ice Probability Chart in the Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 showed a probability of serious carburetor icing at glide power, with a relative humidity of 81 percent.

The Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C) states in part:

Carburetor ice is most likely to occur when temperatures are below 70 degrees Fahrenheit (°F) or 21 degrees Celsius (°C) and the relative humidity is above 80 percent. Due to the sudden cooling that takes place in the carburetor, icing can occur even in outside air temperatures as high as 100 °F (38 °C) and humidity as low as 50 percent.

Whenever the throttle is closed during flight, the engine cools rapidly and vaporization of the fuel is less complete than if the engine is warm. Also, in this condition, the engine is more susceptible to carburetor icing. If carburetor icing conditions are suspected and closed-throttle operation anticipated, adjust the carburetor heat to the full ON position before closing the throttle and leave it on during the closed-throttle operation. The heat aids in vaporizing the fuel and helps prevent the formation of carburetor ice. Periodically, open the throttle smoothly for a few seconds to keep the engine warm; otherwise, the carburetor heater may not provide enough heat to prevent icing.