History of Flight
On March 8, 2019, at 0705 Pacific daylight time, a Richards Heavylift Helo Inc (Bell) UH-1B helicopter, N64RA, was substantially damaged during an accident near Forks, Washington. The pilot was fatally injured. The helicopter was operating under Title 14 Code of Federal Regulations Part 133 as an external load operation, conducting heli-logging using a hydraulic grapple attached to a 180-foot cargo line secured to the helicopter’s cargo hook.
The pilot would typically depart the staging area, fly to the logging site, hover out of ground effect, grapple a log, and return to release the log. A part-time pilot with the company stated that standing trees were about 40 to 50 feet below the helicopter during grappling.
On the accident day, a helicopter mechanic at the staging area assisted with the preflight inspection, observing a normal start, run-up, and takeoff. While walking to the maintenance support trailer, the mechanic heard three distress calls from the pilot over the company radio. Several coworkers also heard the calls and began searching emergency landing areas near the staging area. After finding them empty, one employee hiked to the logging site and discovered the wreckage.
Figure 1 shows the helicopter at the accident site, with a blue cargo line and two black hydraulic hoses running uphill to the grapple hook. The mechanic confirmed the helicopter was fueled with 1,000 pounds of Jet A that morning. He stated he did not check the cargo hook release that morning but had done so the previous day.
Aircraft Information
The helicopter was manufactured in 1965 as a UH-1B, later demilitarized and sold to a private company. In 1997, a Lycoming T53-L13B engine was installed under supplemental type certificate (STC) #SR00073DE. The pilot purchased the helicopter on October 5, 2018.
The mechanic stated it was the pilot’s responsibility to record engine cycles. Maintenance records showed the engine was overhauled on August 1, 2017, with 4,572.3 hours since new, and installed on the accident helicopter on July 2, 2018, at 5,845.0 hours Hobbs time and airframe time of 14,859.5 hours. The engine accumulated 1,068.1 flight hours, 30,509 turns, 294 engine starts, and 934 takeoffs since installation.
Maintenance logs revealed the first stage sealing disk, part number 1-100-135-03, serial number 3694, was installed during overhaul. It had a historical time of 1,067.3 hours and 2,134.6 cycles. Engine cycle documentation was irregular from July 2 to September 17, 2018, after which no documentation occurred. At last documentation, the gas generator cumulative cycles, including the sealing disk, was 9,023.13 cycles.
The helicopter had an AKV N1/N2 cycle counter, examined at AKV Inc, which operated normally and contained correct software. The counter recorded 12,023.19 N1 cycles. The operator could manually add historical values, but there was no documentation of adding the sealing disk’s historical cycles.
Honeywell Aerospace Service Bulletin T53-L-13B-0020 stated the hour/cycle life limit of the first stage sealing disk was 25,000 hours or 6,900 cycles. The bulletin warned that rotating life components must have both hours and cycles tracked to avoid failure.
Wreckage and Impact Information
The helicopter came to rest on steep, mountainous terrain about 1/4 mile from the staging area, surrounded by felled and standing trees. All major structural components were within a small debris field. There was no post-crash fire. The cargo line remained attached to the cargo hook and extended 180 feet uphill to a hydraulic grapple hook. Two hydraulic hoses from the belly followed the cargo line to the grapple, which was resting against a standing tree and holding a log in its jaws (Figure 2). The grappled log rested perpendicular to the cargo line, and part of the grapple had caught the standing tree, consistent with an anchor point.
Examination of the airframe and cargo hook at the site and later at a secure facility revealed no preaccident mechanical malfunctions or anomalies that would have precluded normal operation. The pilot’s cargo hook release button functioned normally.
The engine was examined at Honeywell Aerospace on April 24, 2019. The first stage sealing disk had fragmented into three pieces and separated. Cracks were observed at all six cooling holes. Damage was found on four turbine wheels and other downstream components. Magnified examination of fracture surfaces revealed multiple arc-shaped “beach mark” striations, indicating low-cycle fatigue. Microscopic examination showed both major and minor cycles on the fracture surface.
Additional Information
The US Army technical manual (55-1520-210-10) states the emergency procedure for an engine malfunction in hover is “autorotate” and advises transmitting a “May Day” call if time permits, setting transponder to emergency, jettisoning external stores, and locking shoulder harness.
A part-time pilot disclosed in emails (April 30, 2019 to March 9, 2020) that the accident pilot could lift 29 logs per hour and that he did not track cycles in previous jobs, nor did the accident operator.
Medical and Pathological Information
The FAA Forensic Sciences Laboratory performed toxicology testing on the pilot’s tissue samples. Identified substances included famotidine, naproxen, triamterene, and pseudoephedrine in blood (cavity) and urine. Doxylamine was detected in urine but inconclusive in blood. Norpseudoephedrine (pseudoephedrine metabolite) was detected in urine only. Famotidine (Pepsid), naproxen (Aleve/Naprosyn), pseudoephedrine (Sudafed) are over-the-counter medications not generally considered impairing. Triamterene is a prescription drug for high blood pressure, not generally impairing. Doxylamine is a sedating antihistamine considered by the FAA as a “do not fly” medication.