Accident Overview
On December 16, 2015, about 0942 Alaska standard time, a Robinson R44 II helicopter, registration N255VS, sustained substantial damage during a forced landing following a total loss of engine power during takeoff from Valdez Airport, Valdez, Alaska. The commercial pilot and two passengers were not injured. The helicopter was registered to and operated by Vertical Solutions, LLC, under 14 Code of Federal Regulations Part 91 as a power line patrol flight. Visual meteorological conditions prevailed, and an FAA flight plan had been filed. The flight departed Valdez Airport about 0938.
Pilot Account
During an on-scene interview on December 18, 2015, the pilot stated that he had computed weight and balance and performed a preflight inspection before pushing the helicopter out of the hangar. After passengers boarded and the safety briefing was completed, the engine was started and allowed to warm up for about 5 minutes; all ground run-up checks were satisfactory. After liftoff, the pilot hovered about 10 feet above ground level (AGL) before commencing a left turn, accelerating to about 25 knots, and initiating a climb. As the helicopter climbed through about 20 feet AGL, all engine power was lost. The pilot entered an autorotation, but the helicopter landed hard, sustaining substantial damage to the fuselage, skids, and tail boom.
Engine Examination
The helicopter was equipped with a reciprocating Lycoming IO-540-AE1A5 series engine, with an AVStar RSA-10-AD1 fuel injection servo. On December 18, 2015, an engine examination by the NTSB Investigator-in-Charge (IIC) found no anomalies, contamination, or evidence of malfunction in any engine accessories. The fuel injection servo was removed for further examination and testing. Cylinders, pistons, valve train, crankshaft, and other internal components showed no evidence of anomaly or malfunction. Both magnetos produced strong blue spark in rotational order when rotated.
Maintenance History
A review of maintenance records revealed that the fuel injection servo had been repaired on December 9, 2015, by Alaskan Aircraft Engines Inc., Anchorage, Alaska, and reinstalled about 2.1 hours prior to the accident flight.
Fuel Servo Examination
On January 14, 2016, an NTSB investigator and a representative from AVStar Fuel Systems, Inc. examined the fuel servo at AVStar’s facility in Jupiter, Florida. The servo was placed on a test bench; all test points were within serviceable limits per AVStar Service Bulletin AFS-AB12, except the adjusted idle flow with the adjustment wheel centered was 16.4 lb/hr (specified range 14–15 lb/hr), but this was considered a field adjustment. Disassembly revealed a very small amount of white contamination, ranging from small specks to about 0.10 inch, on the fuel diaphragm, fuel area adjacent to the regulator valve seat, mixture control valve, mixture control plate, and the bore of the valve train opening. Additionally, the interior of the mixture control assembly adjacent to the mixture control stem bushing exhibited evidence of lubricant material consistent with DuPont Krytox.
Lubricant Findings
On January 19, 2016, the NTSB IIC, another investigator, and two FAA inspectors visited Alaskan Aircraft Engines Inc. in Anchorage and disassembled a recently overhauled fuel injection servo. The inspection revealed excessive amounts of a white grease-like substance throughout the servo, consistent with the contamination found in the accident helicopter’s servo. A representative from Alaskan Aircraft Engines stated that about six months prior, they had switched assembly lubricants to DuPont Krytox, an approved lubricant, but due to the investigation, realized it was being used in excess and in locations not approved per the maintenance manual. DuPont describes Krytox 240 series greases as white, buttery greases based on perfluoropolyether oils, chemically inert, nonflammable, and safe for oxygen service. A review of the AVStar servo overhaul manual lists four places where Krytox is to be used, with cautions about excess application and removal of excess lubricant.
On January 19, 2016, Alaskan Aircraft Engines issued a Service Advisory stating that beginning in June 2015, they purchased and began using an approved assembly lube not previously used, which was used in excess and in locations not required by the manufacturer’s service manual, potentially causing a fuel distribution problem.
Weather Conditions
The closest weather reporting facility was Valdez Airport. At 0936, an aviation routine weather report indicated wind calm, visibility 10 statute miles, sky condition broken clouds at 7,000 feet and overcast at 8,000 feet, temperature 21°F, dew point 21°F, and altimeter 29.97 inHg.
Related Events
Before this accident investigation was completed, another Robinson R44 II helicopter experienced a similar event involving a fuel injection servo overhauled by the same repair facility, resulting in a total loss of engine power (see NTSB ANC16IA013).