On November 27, 2014, at 1117 Alaska standard time, a Piper PA-18-150 airplane, N9720P, collided with terrain after a total loss of engine power while maneuvering for an off-airport landing near Nikiski, Alaska. The certificated commercial pilot sustained serious injuries and the sole passenger sustained minor injuries. The aircraft was registered to Summit Leasing LLC and operated by Alaska West Air, Inc., under the provisions of 14 Code of Federal Regulations Part 135 as an on-demand commercial air taxi flight. Visual meteorological conditions prevailed for the entire flight, and a company flight plan was filed. The flight originated from Kenai, Alaska approximately 1030.
In a statement provided to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot stated that prior to the accident he flew approximately 20 to 30 minutes surveying the area for possible landing sites. During this time, he applied carburetor heat three or four times to check for carburetor ice. After a landing site had been selected, the pre-landing checklist was completed, and the carburetor heat was placed in the off position. On short final the engine lost all power. The pilot then switched fuel tanks and turned the carburetor heat back on, but the engine would not restart. The airplane subsequently collided with an area of rising terrain just short of the intended landing site, sustaining substantial damage to the fuselage and wings.
On December 1, 2014, the NTSB IIC, along with another NTSB investigator performed a post-accident examination of the airframe and engine. Control cable continuity was established from the cockpit control to the engine for the throttle, mixture, carburetor heat and cabin heat.
On December 11, the NTSB IIC, along with another NTSB investigator, performed a follow-up examination of the engine and fuel system. No anomalies, contamination, or evidence of malfunction was found in any of the engine accessories. The cylinders, pistons, valve train, crankshaft, and other internal components were all without evidence of anomaly or malfunction that would have precluded normal operation.
Both magnetos were removed from the engine and the coupling was rotated. When the coupling was rotated, a blue spark was produced from each terminal, in rotational order.
The closest weather reporting facility was the Kenai Airport, Kenai, about 31 miles southeast of the accident site. At 1053, an aviation routine weather report (METAR) from the Kenai Airport was reporting in part: wind from 010 degrees at 3 knots; sky condition, clear; visibility, 10 statute miles; temperature 10 degrees F; dewpoint 9 degrees F; barometric pressure 30.23 inHG.
According to a carburetor icing probability chart, an airplane operating in the ambient conditions at the accident site could expect light carburetor icing while at cruise of glide power.
Another company pilot who landed at the same location only minutes before the accident aircraft approached, stated that during the descent, his aircraft had accumulated carburetor ice during the approach.
A Lycoming Service Instruction states in part, "if icing conditions are suspected, apply 'Full Heat.' In the case that full power needs to be applied under these conditions, as for an aborted landing, return the carburetor heat to 'Full Cold' after full power application.