CEN23LA264

A partial loss of engine power as a result of carburetor icing that formed while the engine was operating at a low power setting for an extended period before departure.

The pilot stated that after he started the engine, he let it idle about 600 rpm for a “few minutes,” and began to taxi to the runway for departure. He waited for another airplane to perform a back-taxi and depart, then he back-taxied and completed an engine run-up before realizing he left something behind. He then taxied back to the fixed base operator (FBO), collected his items, and again taxied to the runway for departure. He did not complete another engine run-up before takeoff. During the takeoff roll, he noticed the engine rpm increased and did not note any anomalies. During the initial climb, the engine rpm maintained about 2,200 rpm with full throttle set. He stated that he was able to climb about 500 ft above ground level (agl) and attempted a return to the airport. He said that when he was abeam the runway, he thought he was “losing altitude and power,” and made a shallow left turn towards the runway. Unable to maintain altitude during the turn, the pilot landed on a dirt road. During touchdown, the airplane bounced, exited the roadway, impacted a ditch, and slid into a cornfield, which resulted in substantial damage to the fuselage. During a postaccident examination, no preimpact mechanical malfunctions or failures were discovered that would have precluded normal operation. When the temperature and dewpoint at the time of the accident were plotted on a carburetor icing probability chart, it was revealed that the airplane was operating in an environment conducive for serious carburetor icing at a glide power setting. The pilot stated that he checked the carburetor heat before departure. After the carburetor heat check, it is likely that ice began to form in the carburetor’s venturi during the extended ground operation before departure, which, in turn, limited the engine rpm at 2,200.

On June 24, 2023, about 1130 central daylight time, a Beech B19, N9721Q, sustained substantial damage when it was involved in an accident near Scott City, Kansas. The pilot was uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he added 17.16 gallons of fuel which brought the total quantity to about 30 gallons. He then started the engine, let it idle about 600 rpm for a “few minutes,” and began to taxi to runway 35 at Scott City Municipal Airport (TQK). He waited for another airplane to perform a back-taxi and depart, then he back-taxied and completed an engine run-up before realizing he left something behind. He then taxied back to the FBO, collected his items, and taxied back to the runway for departure. The pilot stated that during the takeoff roll, he noticed that the engine rpm increased and did not note any anomalies. During the initial climb, he saw the engine RPM maintained about 2,200 rpm with full throttle. He stated that he was able to climb to about 500 ft agl and attempted a return to the airport. He said that when he was abeam the runway, he thought he was “losing altitude and power,” and made a shallow left turn towards the runway. Unable to maintain altitude during the turn, the pilot attempted a landing on a dirt road. During touchdown, the airplane bounced, exited the roadway, impacted a ditch, and slid into a cornfield, which resulted in substantial damage to the fuselage. A pilot witness reported seeing the accident airplane depart and noted that it did not appear to be climbing well when it started a turn to the northeast. He estimated the airplane was about 50 to 100 ft agl, when he lost sight of it while he was taxing.  After he turned his airplane around, he saw the accident airplane again when it was southwest of the runway. He stated that it appeared to be less than 100 ft agl and about 30° nose down at the time of impact. During a postaccident examination, continuity was established from the engine controls in the cockpit to their respective engine attach points. No preimpact mechanical malfunctions or anomalies were found that would have precluded normal operation. The reported weather conditions about 15 minutes before the accident included a temperature of 82°F and dewpoint of 59°F.  When plotted on a carburetor icing probability chart, the airplane was operating in an environment conducive for serious carburetor icing at a glide power setting. (See Figure 1) Figure 1: Carburetor Icing Probability Chart. Reference: Special Airworthiness Information Bulletin CE-09-35