Thursday, December 17, 2015

Robinson R44 Raven II, N255VS, Vertical Solutions LLC: Accident occurred December 16, 2015 at Valdez Pioneer Field Airport (PAVD), Valdez, Valdez-Cordova, Alaska

The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities
Federal Aviation Administration; Anchorage, Alaska 
Vertical Solutions; Valdez, Alaska 
AVStar fuel systems, Inc.; Jupiter, Florida 

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Docket And Docket Items - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Aviation Accident Data Summary - National Transportation Safety Board:  https://app.ntsb.gov/pdf

Vertical Solutions LLC: http://registry.faa.gov/N255VS

NTSB Identification: ANC16LA010
14 CFR Part 91: General Aviation
Accident occurred Wednesday, December 16, 2015 in Valdez, AK
Probable Cause Approval Date: 03/06/2017
Aircraft: ROBINSON HELICOPTER COMPANY R44 II, registration: N255VS
Injuries: 3 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The commercial pilot was departing on a power line patrol flight in the helicopter. After liftoff, the pilot hovered the helicopter about 10 ft 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 ft agl, the engine experienced a total loss of power. The pilot performed an autorotation, but the helicopter landed hard, resulting in substantial damage to the fuselage, skids and tail boom.

Review of the accident helicopter’s maintenance records revealed that the fuel injection servo had been repaired and reinstalled about 2 hours before the accident flight. During postaccident examination of the fuel injection servo assembly, small amounts of a white, greasy substance were discovered in the servo assembly. The greasy substance, later identified as DuPont Krytox, is a lubricant used in small amounts and specific locations, during reassembly after overhaul or maintenance of the fuel injection servo assembly. 

Inspection of a fuel injection servo from a different helicopter that had been overhauled by the same maintenance facility revealed similar contamination. A representative from the maintenance facility stated that about 6 months before the accident, they had begun using Dupont Krytox, an approved lubricant, but did not realize that it was being used in excess and in locations not approved per the maintenance/service manual. 
Due to the improper and excessive use of assembly lubricant and the lack of engine anomalies, it is likely that the lubricant contaminated the fuel injection servo, causing a disruption in fuel flow, which resulted in a total loss of engine power.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The overhaul facility’s improper and excessive use of an approved lubricant during overhaul of the fuel injection servo, which resulted in a disruption of fuel flow and a total loss of engine power. 

On December 16, 2015, about 0942 Alaska standard time, N255VS, a Robinson R44 II helicopter, sustained substantial damage during a forced landing following a total loss of engine power during takeoff from the 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 the provisions of 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.

During an on-scene interview with the National Transportation Safety Board (NTSB) Investigator-in-Charge (IIC) on December 18, 2015 the pilot stated that he had computed the weight and balance, and performed a preflight inspection prior to pushing the helicopter out of the hangar. After the passengers boarded the helicopter, and the passenger safety briefing was completed, the engine was started and allowed to warm up for about 5 minutes, and all ground run-up checks of the engine were satisfactory. He stated that after liftoff he hovered the helicopter 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. He entered an autorotation but the helicopter landed hard, sustaining substantial damage to the fuselage, skids and tail boom.

The helicopter was equipped with a reciprocating Lycoming IO-540-AE1A5 series engine, equipped with a AVStar RSA-10-AD1 fuel injection servo. 

On December 18, 2015, an engine examination was performed by the NTSB IIC. No anomalies, contamination, or evidence of malfunction was found in any of the engine accessories, but the fuel injection servo was removed for further examination and testing. The cylinders, pistons, valve train, crankshaft, and other internal components were all without evidence of anomaly or malfunction. 

Both magnetos were removed from the engine and the coupling was rotated. When the coupling was rotated, strong blue spark was produced from each terminal, in rotational order. 

A review of the helicopter's maintenance records revealed that the fuel injection servo had been repaired on December 9, 2015 by Alaskan Aircraft Engines Inc., Anchorage, Alaska, and had been reinstalled on the helicopter about 2.1 hours prior to the accident flight.

On January 14, an NTSB investigator and a representative from AVStar Fuel Systems, Inc. examined the fuel injection servo at the facilities of AVStar Fuel Systems, Inc. in Jupiter, Florida. The fuel servo was placed on the test bench, and all test points were within serviceable limits using AVStar Service Bulletin AFS-AB12 "Service Limits for AVStar Fuel Servos" with the exception of the adjusted idle flow with adjustment wheel centered. The adjusted idle flow with fuel wheel centered should be between 14 – 15 pounds per hour (lb/hr), and was found to be at 16.4 lb/hr, but this is considered a field adjustment. 

Disassembly inspection revealed a very small amount of white contamination ranging in size from small specs to about 0.10 of an inch. The contamination was present on the fuel diaphragm, the fuel area adjacent to the regulator valve seat, mixture control valve, mixture control plate, and the bore of the valve train opening. In addition, the interior of the mixture control assembly adjacent to the mixture control stem bushing exhibited evidence of lubricant material consistent with DuPont Krytox. 

On January 19, the NTSB IIC along with another NTSB investigator, and two FAA aviation safety inspectors visited the facilities of 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 fuel injection servo, consistent with the white contamination noted in the servo removed from the accident helicopter. A representative from Alaskan Aircraft Engines stated that about 6 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 in part: "As white, buttery greases based on perfluoropolyether (PFPE) oils. These synthetic fluorinated lubricants are used in extreme conditions such as continuous high temperatures up to 300°C (572°F) and higher temperatures for shorter periods, depending on product grade limits. Chemically inert and safe for use around hazardous chemicals, these lubricants are nonflammable and are safe for use in oxygen service."

A review of the AVStar Servo Fuel Injector Overhaul and Repair Manual for the RSA-10-AD1 fuel injection servo assembly lists four places where DuPont Krytox is to be used during assembly states, in part: 

"LAPPING THE VALVE-LOWER IDLE, SHAFT-IDLE VALVE, AND THE PLATE-MIXTURE CONTROL 

Before reassembly with mating parts, very lightly apply DuPont Krytox to one mating surface.

CAUTION! Do not allow any amount of Krytox to enter a hole, a slot or reach any edge of the part to which it has been applied.

Carefully remove any Krytox. 

SERVO ASSEMBLY 

Apply DuPont Krytox to the lever assembly-mixture control. Apply carefully to the space between the lever stop and the packing-preformed. 

NOTE! Remove excess Krytox with P-D-680, Acetone or MEK, as needed. 

Apply DuPont Krutox grease to the idle valve shaft outboard of the packing-preformed. 

NOTE! Remove excess Krytox with P-D-680, Acetone or MEK, as needed. 

Apply a light coat of Krytox on the concave side of seal-servo. Place the seal-servo stem over the bullet with the concave side up. Press seal down on diaphragm stem. Remove all traces of lubricant from the bullet and the stem." 

On January 19, 2016 Alaskan Aircraft Engines issued a Service Advisory that stated, in part: "Beginning in June of 2015 Alaskan Aircraft Engines purchased and began use of an approved assembly lube it had not used previously. This lube was used in excess and in locations not required by the manufacturer's service manual. We believe this has the potential to cause a fuel distribution problem." A complete copy of the Service Advisory is included in the public docket for this accident. 

The closest weather reporting facility is Valdez Airport. At 0936, an aviation routine weather report (METAR) at Valdez, Alaska, reported in part: wind, calm; visibility, 10 statute miles; sky condition, broken clouds 7,000 feet, overcast 8,000 feet; temperature, 21 degrees F; dew point 21 degrees F; altimeter, 29.97 inHG.

Additional Information


Before this accident investigation was completed (and before the results of the component examinations were known) another Robinson R44 II helicopter experienced a similar event involving a fuel injection servo overhauled by the same repair facility that resulted in a total loss of engine power. See NTSB ANC16IA013 for more information about that incident.

NTSB Identification: ANC16LA010 
14 CFR Part 91: General Aviation
Accident occurred Wednesday, December 16, 2015 in Valdez, AK
Aircraft: ROBINSON HELICOPTER COMPANY R44 II, registration: N255VS
Injuries: 3 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On December 16, 2015, about 0942 Alaska standard time, a Robinson R44 II helicopter, N255VS, sustained substantial damage during a forced landing following a total loss of engine power during takeoff from the Valdez Airport, Valdez, Alaska. The commercial pilot and two passengers were not injured. The helicopter was registered to and operated by Vertical Solutions, LLC, of Valdez, under the provisions of 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.

During an on-scene interview with the National Transportation Safety Board (NTSB) Investigator-in-Charge (IIC) on December 18, 2015, the pilot stated that he had computed the weight and balance, and performed a preflight inspection prior to pushing the helicopter out of the hangar. After the passengers boarded the helicopter, and the passenger safety briefing was completed, the engine was started and allowed to warm up for about 5 minutes, and all ground run-up checks of the engine were satisfactory. He stated that after liftoff the helicopter was held in about a 10 foot hover above ground level (agl), before commencing a left turn, accelerating to about 25 knots and initiating a climb. He reported that as the helicopter climbed through about 20 feet agl, all engine power was lost. The pilot entered an emergency autorotation and landed the helicopter on an adjacent taxiway. During touchdown, the helicopter landed hard, sustaining substantial damage to the fuselage, skids, and tail boom.

The helicopter was equipped with a Lycoming IO-540-AE1A5 series engine, a detailed engine examination is pending. 

The closest weather reporting facility is Valdez Airport. At 0936, an aviation routine weather report (METAR) at Valdez, Alaska, reported in part: wind, calm; visibility, 10 statute miles; sky condition, broken clouds 7,000 feet, overcast 8,000 feet; temperature, 21 degrees F; dew point 21 degrees F; altimeter, 29.97 inHG.

FAA Flight Standards District Office: FAA Anchorage FSDO-03

Officials in Valdez say three people on Wednesday survived a hard landing by a helicopter at the city airport.

City public information officer Allie Hendrickson says a bystander witnessed the Vertical Solutions helicopter landing hard at Pioneer Field Airport and called emergency officials.

An announcement by the Copper Valley Electric Association says two association employees had contracted the helicopter to patrol electricity transmission lines from the air and it took off just before 9:30 a.m.

When the helicopter reached 75 feet, it lost power and fell.

CVEA says the tail section separated from the rest of the helicopter.

The association says its two employees were shaken but not injured. They were to be examined by a doctor.

Hendrickson says there was no damage to airport property or other aircraft.

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