WPR24LA117

The pilots inability to fully turn off the carburetor heat which resulted in a reduction of engine power and reduced climb performance. Contributing to the accident was the pilots delayed recovery from the simulated emergency landing.

The private pilot applicant and designated pilot examiner (DPE) were conducting a simulated engine failure exercise as part of the flight portion of a private pilot practical test. Once satisfied that the applicant would successfully complete an emergency landing, the DPE announced the end of the exercise and asked the applicant to initiate a go-around. The applicant advanced the throttle to full forward, turned the carburetor heat off, and pitched the airplane for 66 kts. A few seconds later, the applicant informed the DPE that the airplane didn’t seem to be climbing, and the DPE checked the airplane’s climb configuration, confirming full throttle, full rich mixture, carburetor heat cold, and flaps up. Both pilots noted that the tachometer was displaying about 2000 rpm. During the simulated emergency descent and subsequent go-around, the airplane was flying toward rising terrain. The DPE attempted several shallow turns toward lower terrain; however, he could not turn without losing altitude, so did not turn away from the rising terrain. He identified a flat area on top of a ridge and executed an emergency landing on the ridgeline in heavy brush, about one mile from the go around initiation point. Postaccident examination of the wreckage revealed that the carburetor heat control cable was improperly attached to the carburetor heat control arm, which restricted travel of the airbox heat door and the cabin-mounted carburetor heat control knob. The improper attachment restricted the heat door from closing fully in the carburetor heat OFF position but did not restrict the heat door from closing fully in the ON position. The inability to fully close the carburetor heat into the OFF position could have resulted in a reduction in engine power; however, an exact amount of engine rpm reduction could not be determined. Postaccident test run of the engine revealed that it produced full power and showed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The reason for the partial loss of engine power could not be determined. Both pilots reported that they initiated the go-around while about 800 ft above ground level (agl); however, recorded flight data from the airplane’s avionics indicated that the airplane had descended to about 90 ft agl when the go-around was initiated. The airplane then attained an average climb rate of 310 ft per minute between the initiation of the go-around and the accident site. The elevation at the accident site was 381 ft higher than the elevation where the go-around was initiated. While flying into rising terrain, the airplane could have appeared to the pilots that it was not climbing, despite the documented climb rate. However, the partial loss of engine power likely prevented the airplane from outclimbing the rising terrain.

On March 22, 2024, about 1804 Pacific daylight time, a Piper PA-28-140, N1695H, was substantially damaged when it was involved in an accident near Acton, California. The private pilot applicant and designated pilot examiner were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight test. According to statements from the DPE and private pilot applicant, they were conducting the flight portion of a private pilot practical test. The DPE announced a simulated engine failure and reduced the engine power to idle. The private pilot applicant turned on the carburetor heat and performed the simulated emergency procedures for an engine failure. At approximately 800 ft agl the DPE instructed the applicant to go around, ending the simulated emergency. The applicant increased the engine power by advancing the throttle full forward, turning the carburetor heat off, and pitching the airplane for an indicated airspeed of 66 knots. After about 10 seconds, the applicant stated to the DPE that the airplane would not climb. The DPE confirmed that the throttle control was set to full power, mixture control was set to full rich, carburetor heat control was set to off, and that the flaps were up. He noticed that the tachometer indicated about 2000 rpm. The DPE took control of the airplane and attempted to turn away from rising terrain; however, the airplane would not maintain altitude in a turn. The DPE continued straight ahead and determined that the airplane would not outclimb the surrounding terrain, then prepared to make an emergency landing. The DPE initiated a landing along a ridgeline about 1 mile south of the go around initiation point. During the landing, the airplane impacted vegetation and came to rest upright. It sustained substantial damage to both wings, the fuselage, and the stabilator. Postaccident examination of the airframe revealed limited function of the heat door within the airbox. The carburetor heat control arm traveled from stop to stop; however, the heat door only exhibited about half its designed travel. It traveled from the carburetor heat ON position to halfway between carburetor heat OFF and ON. The carburetor heat control cable was looped around the attachment bolt and found to be loose; it was not threaded through the attachment bolt, and no safety wire was observed. The carburetor heat control knob inside the cabin traveled without binding but exhibited limited travel and was found to travel between the “Carburetor Heat OFF” position and about halfway to the “Carburetor Heat ON” position. A postaccident test run of the engine was conducted and revealed that it produced full power and showed no anomalies that would have precluded normal operation. Accident flight data from the airplane’s Garmin G5 was downloaded and indicated that the simulated emergency descent was flown toward agricultural fields, and rising terrain. Recovery from the simulated engine failure began at approximately 90 ft agl, and the airplane achieved an average rate of climb of 310 fpm from the exercise’s go-around point to the accident site. The geographical change in elevation from the go-around point to the accident site was +381 ft and the lateral distance was about one mile. According to maintenance records, the most recent annual inspection was completed on April 14, 2023, and the most recent maintenance logbook entry related to the travel of carburetor heat controls, was March 11, 2024.