ANC24LA049

The pilot and five passengers departed from a remote lake in the float-equipped airplane. The pilot reported that, shortly after takeoff, he felt the manifold pressure decrease, and he advanced the propeller and throttle controls. The engine initially responded with an increase in rpm and manifold pressure but subsequently lost total power. The pilot performed a forced landing into a heavily wooded area, and the airplane sustained substantial damage to the fuselage and wings. A postaccident examination of the engine revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal engine operation. Passengers reported that the pilot made an aggressive steep turn at low altitude with no change in engine noise from takeoff to impact with terrain. Based on available evidence, it is likely that the engine sustained a partial loss of engine power for reasons that could not be determined.

On June 10, 2024, about 1635 Alaska daylight time, a DeHavilland DHC-2 airplane, N4957, was substantially damaged when it was involved in an accident near Port Alsworth, Alaska. The pilot and four passengers were not injured; one passenger was seriously injured. The airplane was operated by Talon Air Service, Inc., as a Title 14 Code of Federal Regulations Part 91 other work use flight. According to the operator, the float-equipped airplane departed with five passengers from Kijik Lake, Alaska, destined for Longmere Lake, near Soldotna, Alaska. The pilot performed an engine run-up, then taxied the airplane to the edge of the lake for takeoff. After takeoff from the lake, the pilot adjusted the manifold pressure, engine rpm, and flaps for climb. About three miles after takeoff, the pilot reported he felt the manifold pressure decrease. He increased the propeller and throttle controls, and the engine initially responded with an increase in rpm and manifold pressure, but subsequently lost total power. The pilot performed a forced landing into a heavily wooded area, resulting in substantial damage to the fuselage and wings. A postaccident engine examination revealed that the engine rotated freely by hand. The spark plugs were undamaged and exhibited normal wear. The cylinder bases and cylinder base nuts were present and did not have any distortion or evidence of damage from over-boosting. Examination of the exhaust and induction systems revealed no anomalies. All engine controls functioned properly and exhibited full travel when manipulated. The main fuel line was disconnected at the engine side of the firewall and fuel flowed from all three tanks. The magnetos were secure on their mounts, and the timing was set at about 24° before top dead center. The oil screen was removed, inspected, and re-installed; no debris was observed, and it was free of any magnetic material. The propellers exhibited tip bending consistent with impact; however, there was no rotational scoring present. No abnormalities were observed with the engine that would have precluded normal operation. Two passengers reported that there was no change in engine noise from takeoff to impact with terrain, with one passenger reporting an increase in engine noise about five seconds before impact. Passengers reported that the pilot made a hard left turn, with one passenger describing it as “the airplane was nearly on its side,” in a “near vertical attitude.” The turn felt like an “extreme maneuver,” with the airplane too low for such a steep turn. They stated there was no warning from the pilot before the impact. The operator reported that the airplane’s gross weight at the time of takeoff was 5,030 lbs, and that its maximum gross weight was 5,370 lbs.