NTSB Factual Report

On August 31, 2014, about 1800 Alaska daylight time, a deHavilland DHC-2 "Beaver" airplane, N93E, was substantially damaged during a collision with trees and terrain following a loss of engine power during takeoff from Lake Hood Strip, Anchorage, Alaska. Of the four people on board, one passenger received minor injuries and the private pilot and two additional passengers were not injured. The flight was being operated as a visual flight rules (VFR) personal flight under the provisions of 14 Code of Federal Regulations Part 91 when the accident occurred. Visual meteorological conditions prevailed and no flight plan was filed for the flight destined for a hunting camp approximately 30 miles west of Anchorage.

In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) following the accident, the pilot stated he was making a second trip to camp that day when the engine lost power after takeoff at an altitude of about 100 feet above ground level. He unsuccessfully attempted to restart the engine, and made a forced landing in an area of densely populated spruce trees. During the forced landing the airplane sustained substantial damage to the fuselage, wings, and horizontal stabilizer.

The engine and airframe were examined by the NTSB IIC at the facilities of Alaska Aircraft Sales on September 4. No airframe anomalies were noted that would have precluded normal operation. The engine was examined, and all the internal components were intact and functional. The magnetos, carburetor, and engine driven fuel pump were removed from the engine for further examination.

On December 4 and again on January 14, 2015, the NTSB IIC, along with another NTSB investigator examined the removed engine accessories at the facilities of Alaskan Aircraft Engines. The magnetos and carburetor were tested with no anomalies noted. The engine driven fuel pump was tested on two separate test benches, and run through a variety of RPM/Fuel Flow/Fuel Pressure tests. Fuel flow results from the various tests revealed widely inconsistent flow rates under the same test conditions. A control fuel pump was also tested on the same equipment, with consistent results in fuel flow.

The pump was disassembled and several anomalies were noted. The spline driver oil seal on the spline driver shaft was split, and was protruding through the opening in the spline driver thrust washer. The engine oil seal was not found inside the pump. It is unknown if the engine oil seal was installed, or if the ring itself deteriorated inside the housing. The overall appearance of the seal housing and pump bearings were dirty and numerous pieces of foreign matter were noted within the seal and pump housing.

The fuel pump was installed on the airplane on November 1, 2000, and the engine had accrued about 520 hours of operation since the install.

NTSB Probable Cause

The loss of engine power during takeoff due to a malfunction of the engine-driven fuel pump.