CEN13FA075

The improper maintenance of the helicopter fuel system that resulted in erroneous fuel gauge indications and the pilot’s inadequate fuel management, both of which resulted in fuel exhaustion during a long-line hover. Also causal was the lack of company procedures to ensure adequate maintenance and fuel planning.

The helicopter was in a hover about 120-150 feet above the ground while a utility worker performing a long-line operation worked on a transmission tower. After the loss of power, the helicopter spun and descended during which the worker was pulled off the tower by the attached long line. The pilot performed an autorotation that resulted in a hard landing. The pilot sustained serious injuries and the worker sustained fatal injuries. Postaccident examination of the helicopter revealed no usable fuel on board, and fuel quantities between the fuel tank and engine were consistent with fuel exhaustion. The examination revealed that the electrical wire to the start pump was not secured, which allowed for the possibility of it interfering with the fuel quantity transmitter float mechanism, thus providing erroneous cockpit fuel quantity indications to the pilot. The examination also revealed that the low fuel quantity annunciator was inoperative due to separation of the fuel quantity transmitter's low-level fuel whisker. Recent maintenance of the helicopter's fuel system by the operator's maintenance personnel included the replacement of the start pump and testing of the low-level fuel light by electrically grounding the top of the fuel quantity transmitter using safety wire. A vacuum check of the fuel system was not performed after the fuel system had been opened. The method for testing the low-level fuel light and the lack of a vacuum check were not in accordance with the maintenance manual and the helicopter manufacturer's service bulletin relating to the start pump installation. Postaccident examination of the helicopter also revealed a nonstandard installation of an engine mounted fuel filter petcock drain valve. No written company procedures and/or fueling records were available that required pilots to track fuel loading and time-based fuel consumption in order to determine time remaining for flights and their termination. The pilot stated that he would have the helicopter refueled when the fuel gauge indicated about 100 lbs. However, had the operator and/or pilot calculated the flight time remaining based on known fuel quantities that were independent of fuel gauge indications, then any fuel gauge inaccuracies would be have become apparent.

The start pump wire was placed in various positions over the fuel quantity float/transmitter float in which the wire was resting on the wire and in position that entangled the wire with the float and the corresponding cockpit fuel gauge indication was recorded. With the float resting on the wire, the gauge indication was about 125 lbs. With the wire on a notch that was on the left side of the float, the gauge indication was about 90-100 lbs. With the wire entangled and to the left, the gauge indication was about 140 lbs. With the wire on the upper (outboard) side of the float are near its pivot, the gauge indication was about 100 lbs. A metallurgical examination of fuel low level spring wire's mating surface was performed by the National Transportation Safety Board's Materials Laboratory. A report of the examination stated that the based on the flat fracture appearance, the presence of ratchet marks, and crack arrest features, a fatigue crack initiated in the whisker. Due to the stepped structure associated with the fracture surface and oxidation on the surface, a demarcation for the fatigue terminus could not be reliably established. However, the presence of microvoid coalescence fracture features in the approximate center of the whisker indicate that final fracture of the whisker was due to overstress. The fuel truck from which the helicopter was last refueled from had been moved from the accident site to outside a residence in Childress, Texas, by the time investigators arrived on-scene. Investigators examined the truck at that residence the day after the accident. The truck was labeled Brim Aviation truck number 66 and was equipped with a tank labeled Jet A. The truck odometer was 93,275 miles. There were two bottles of 5-Hour Energy in a black colored metal wire-mesh basket located on the floor in the front seat area of the truck. The tank on the truck had a meter that indicated a total of 49,498.9 gallons and about 375.07 gallons of fuel pumped. A filter housing, installed between the fuel tank pump output and fueling hose, did not have a filter change date and did not have identifying information on the external housing. The housing was not removed to examine the presence of a filter element nor the condition of the filter element. A binder aboard the truck had paperwork that stated that the fuel filter was changed "DEC 2010", and the last date that the fuel nozzle, tank, and filter were checked for contaminants and water was October 4, 2012. The following page in the binder had a blank entry next to the truck number and the page had its last entry dated "11/30". The "From ODO Reading" on the page was "63770" and the "To ODO Reading" was blank. Three entries for "11/30" stated: Meter Start - 19415; Meter Stop - 19544; Total - 530; Jet A Loaded - Full Meter Start - 19726; Meter Stop - 19822; Total - 600; Jet A Loaded – blank with "-96" next to the column Meter Start - 19822; Meter Stop - 20103; Total - 500; Jet A Loaded – 220 with "-281" next to the column The FAA allowed the carriage of persons under Part 133.35 when the human external-load is "necessary to accomplish the work activity directly associated with the external-load operation." Part 1 defined four distinct rotorcraft-load combinations (RLC). Class B RLC was defined as one in which "the external load is jettisonable and is lifted free of land or water during the rotorcraft operation." Part 133.1(d) stated that persons "other than a crewmember or a person who is essential and directly connected with the external-load operation may only be carried in approved Class D RLC." Brim Aviation provided rotorcraft external-load services for Great Southwest, carrying Great Southwest utility workers via long-line under the provisions of Part 133 Class B external-load operations. According to the company Operations Specifications, Brim Aviation's principal base of operations was located at Ashland, Oregon, and no other bases were listed. The Lubbock FSDO did not know Brim Aviation was operating within their geographic service, which included Childress, Texas, and were not required to be notified by the operator or by the Portland FSDO of these operations. The Portland FSDO had oversight responsibility of Brim Aviation and did not know of Brim Aviation's operations in the Childress and Wellington, Texas areas. The long-line worker, who was on the ground and witness to the accident, was requested during his interview by the National Transportation Safety Board Investigator-In-Charge (IIC) to provide the training materials he received during his training at ARS. These materials were not received by the IIC. FAA Aviation Safety Program publication, FAA-P-8740-03, Time In Your Tanks, states in part: "…the amount of useable fuel in your aircraft equates directly to how long your aircraft will fly. The longer you can fly, the more choices you have for ensuring a safe flight, consequently you can say flight time equates directly flight safety. …" The aircraft was a MD Helicopters, Inc. MD 500D (Hughes 369D), serial number 970191D, helicopter certified under Civil Air Regulations (CAR) Part 6. The helicopter was purchased by and registered to Brim Equipment Leasing Inc. in 2005 and was used in long-line and law enforcement operations. The helicopter was powered by a Rolls Royce, 250-C20B, serial number CAE-836143, engine. The helicopter was equipped with an ARS-Air Rescue Systems (ARS) belly band, part number: "ARS-3RR 10a", date of manufacture: "22389-312A-10 of 10", date-in-service: "6-3-12". The last maintenance inspection on the helicopter was a 100-hour inspection dated November 17, 2012, at an aircraft total time of 15,301.6 hours and a Hobbs time of 5,901.4 hours. The helicopter flew about 4 or 5 times since that inspection, which was performed in a hangar at Brim Aviation's Wellington, Texas, facility. According to the MD 500D Rotorcraft Flight Manual, section 2-11, Fuel System Limitations, Table 2-1, lists the usable fuel for standard non self-sealing fuel tanks as 1.9 gallons. Section 3-13, Fuel System Malfunctions, states that "FUEL LEVEL LOW" indicator would be "ON" when approximately 35 lbs of fuel (22.5 lbs usable) remain in the fuel tank. Investigators examined the helicopter for the presence of a maintenance discrepancy log. The only log found aboard the helicopter that contained a section for discrepancies, titled "PILOTS REMARKS OR DISCREPENCIES," was contained in a "Brim Aviation Engineering Log Book Report." The Brim Aviation Engineering Log Book Report began with its first entry on page 2401, dated November 11, 2011, and ended with its last entry on page 2446, which was not dated. Page 2445 was dated November 16, 2012. Only two pages within The Brim Aviation Engineering Log Book Report contained airworthiness entries within the discrepancies section, which were on pages 2409, undated, and 2410, dated February 18, 2012. The discrepancy entry on page 2409 was: "Throttle friction sticky" and "Pilot's door exterior handle non operational." The discrepancy entry on page 2410 was: "Pilot's exterior door handle – inop," "Gov. control linkage – Bolt spins – Retighten & Re cotter," "Reinstall Skid Mirror," Reinstall Steps." There were no entries within the "POWER CHECKS" section for any of the pages from 2401 to 2445. The pilot stated that engine trend monitoring was not performed. The PILOTS REMARKS OR DISCREPENCIES sections of the remaining pages within this log contained flight/customer information. According to page 2440 of the log, an entry dated October 17, 2012, at a Hobbs time of 5,817.3 hours, and aircraft total time of 15,217.5 hours, within the "MECHANICS: CORRECTIVE ACTION & LIST ALL MAINTENANCE PERFORMED," states in part: "Replaced airframe anti ice filer with new part." "Drained and wiped clean fuel cell bladders, removed, cleaned, and reinstalled fuel boost pump." "All work done IAW csp-hmi-2 and Rol