N802CE

"***This report was modified on September 9, 2019. Please see the docket for this accident to view the original report.***"

HISTORY OF FLIGHT

On June 6, 2016, about 1530 Alaska daylight time, a tailwheel-equipped Air Tractor AT-802 airplane, N802CE, lost engine power while en route to Fairbanks, Alaska, and collided with large trees and steep, rocky terrain during a forced landing near the Murphy Dome Air Force Station, about 22 miles northwest of Fairbanks. The commercial pilot, the sole occupant, sustained no injury, and the airplane sustained substantial damage. The airplane was registered to, Arctic One, LLC, Fairbanks, and was operated by, Everts Air Fuel, Inc., Fairbanks, as a visual flight rules (VFR) commercial bulk fuel transportation flight under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the time of the accident, and company flight following procedures were in effect. The flight originated from the Rampart Airport (RMP) in Rampart, Alaska, about 1510.

The pilot had two scheduled bulk fuel delivery operations for the day. The bulk fuel is transported in the hopper of the airplane. The first operation consisted of delivery of bulk fuel to Stevens Village Airport (SVS), Stevens Village, Alaska and the second operation consisted of delivery of bulk fuel to RMP. SVS is about 90 miles northwest of Fairbanks International Airport (FAI), Fairbanks. RMP is about 82 miles northwest of FAI. Both Stevens Village and Rampart are remote communities situated next to the Yukon River.

Prior to departing for SVS, the pilot added 90 gallons of fuel to an unknown amount of fuel in the airplane's fuel tanks at FAI. The pilot departed FAI about 1100 and flew to SVS and unloaded the bulk fuel from the hopper without further incident. The pilot departed from SVS about 1210 and landed at FAI. Upon landing at FAI, the Shadin Avionics fuel flow indicator showed 167 gallons of fuel in the airplane's fuel tanks. The pilot added 20 gallons of fuel to the right wing fuel tank prior to departing for RMP, for a total of 187 gallons of fuel in the airplane's fuel tanks, as shown by the Shadin fuel flow indicator. The pilot did not report what the fuel gauges were reading at this time. For the trip to RMP, the pilot reported the travel time was about 25 minutes and the wind condition was "negligible." The pilot landed at RMP and unloaded the bulk fuel from the hopper without further incident. The pilot did not conduct any refueling operations for the airplane at RMP.

The operator reported that on the climb out from Rampart, the low fuel warming (red) light in the cockpit was flickering but went away. About halfway to FAI, the pilot reported the low fuel warning (red) light illuminated. About 20 miles out from FAI, shortly after calling Fairbanks Approach Control, the pilot reported the engine ceased producing power. He noted that the fuel flow indicator showed that he was going to land with 95 gallons remaining in the fuel tanks. The pilot immediately executed the engine out emergency procedures with no success. The pilot lowered the nose and "rocked" the airplane to see if the engine would restart. The engine still did not produce power. The pilot reported the loss of engine power to Fairbanks Approach Control. The pilot proceeded with the engine out checklist, feathered the propeller, shut off the various airframe systems, and prepared for a forced landing.

He attempted to land the airplane at the Murphy Dome Air Force Station, a permanently closed U.S. Air Force (USAF) radar site. The pilot was unable to achieve a forced landing at the Murphy Dome Air Force Station and landed the airplane in a remote area with various large spruce trees and steep, rocky terrain, about 2 miles northwest of the Murphy Dome Air Force Station. The airplane subsequently struck several trees and terrain during the landing and came to rest upright. The airplane sustained substantial damage to the fuselage, both wings, and the empennage. At 1549, the Federal Aviation Administration (FAA) issued an Alert Notice (commonly referred to as an "ALNOT") for the airplane. A USAF HH-60G (Pave Hawk) helicopter with a team of USAF Pararescuemen from Joint Base Elmendorf-Richardson, Alaska, traveled to the accident site and retrieved the pilot.

AIRCRAFT INFORMATION

The Air Tractor AT-802 is a two-seat tandem cockpit, restricted category airplane originally designed for use in aerial application operations. The operator had the airplane modified for the transportation of bulk fuel. The airplane can also be configured and used for other operations such as aerial firefighting and attack/reconnaissance missions for military forces. The airplane was powered by a Pratt & Whitney Canada PT6A-67F turbine engine with a 5-blade Hartzell propeller. For carrying a liquid product such as bulk fuel, the maximum hopper load is 8,800 pounds (800 gallons).

METEOROLOGICAL INFORMATION

FLIGHT RECORDERS

The airplane did not carry, nor was required to carry, a crashworthy flight data recorder.

WRECKAGE AND IMPACT INFORMATION

Airframe and Engine Examination

The wreckage was recovered and transported to a secure facility for future examination of the airframe and engine. During the recovery operation, the operator reported that both fuel tanks remained intact from the accident sequence and no usable fuel was found in either fuel tank. On July 15, 2016, a wreckage examination and layout were done under the direction of the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) at the operator's hangar at FAI. Also present were two air safety investigators from the NTSB, an aviation safety inspector from the FAA Fairbanks Flight Standards District Office (FSDO), an air safety investigator from Air Tractor, two air safety investigators (technical advisors) from Pratt & Whitney Canada, and two representatives from Everts Air Fuel. During the examination, no preimpact mechanical malfunctions or failures with the airframe and engine were noted.

During the examination of the header tank, a total of 3 quarts of fuel was drained from the header tank sump location. The fuel was found to be clear with no significant debris or contamination. It was noted by Air Tractor, that 3 quarts of fuel would bring the fuel level down to the top of the header tank fuel pickup (suction) tube and considering in-flight sloshing, it is likely that the fuel system would have ingested large amounts of air with this fuel level.

Engine Accessories Examination/Testing

The flow divider, fuel pump, and the fuel control unit were removed from the engine and transported to facilities of Pratt & Whitney Canada, located in Quebec, Canada. The three components were examined and tested on September 15, 2016 under the direction of the Accredited Representative of the Transportation Safety Board of Canada, along with a technical advisor from Woodward. During the examination and testing, no preimpact mechanical malfunctions or failures with the three components were noted.

Fuel Sensing Components Examination/Testing

The fuel sensing components of the airplane were transported to the facilities of Air Tractor, located in Olney, Texas. The fuel gauging system, the low fuel warning system, and the fuel flow indicator were examined and tested on October 13, 2016 under the direction of an aviation safety inspector from the FAA Lubbock (Texas) FSDO. During the examination and testing, no preimpact mechanical malfunctions or failures with the fuel sensing components were noted.

Per the Air Tractor AT-802 Airplane Flight Manual (AFM), the low fuel caution light is set to illuminate when the fuel in either wing tank reaches approximately 14 gallons of usable fuel. Assuming equal fuel levels in each wing, this would be approximately 28 gallons of usable fuel remaining in the wing tanks.

When utilizing an average fuel burn of 110 gallons per hour for the Pratt & Whitney Canada PT6A-67F engine, 28 gallons of fuel would provide about 15 minutes of flight time.

During the examination of the fuel flow indicator, which reads in gallons, the indicator was plugged into a bench test harness and power was applied with a benchtop power supply. When power was applied, the indicator ran a self-test and returned the word "- GOOD -" indicating that the self-test was successful. Pushing the "Used/Rem" switch down displayed the value of 96.4, gallons which is the calculated fuel remaining on board. Pushing the "Used/Rem" switch upward displayed the value of 77.4 gallons, which is the measured fuel used since the last input/reset of the indicator. It was noted that the indicator was marked on the outside and in the programming with a K-factor of 23.1 (K-factor is the number of pulses expected for every one volumetric unit of fluid passing through a given flow meter). It did not appear that the indicator had been tampered with or reprogrammed since the accident occurred.

The fuel flow indicator has no fuel level sensing capabilities. The fuel remaining calculation relies solely on the pilot's input of fuel added. The indicator then subtracts the gallons used (using the fuel flow transducer) as the flight proceeds and fuel is used. Adding the values of 96.4 and 77.4 together indicates that the fuel flow indicator was programmed with 173.8 gallons of fuel onboard at the last fueling or instrument reset.

Per the Shadin Avionics Microflo-L Digital Fuel Management System Operating Manual, a visual inspection and positive determination of the usable fuel in the fuel tanks is a necessity. The manual further states that it is imperative that the determined available usable fuel be manually entered into the system.

SURVIVAL FACTORS

Emergency Locator Transmitter

The airplane was equipped with an Artex ME-406 emergency locator transmitter (ELT), a C126 (406 MHz) series. The ELT, which remained mounted to the airframe and connected to the antenna a...