History of Flight
On May 28, 2014, at 1433 Alaska daylight time, a Robinson R44 Raven II helicopter, registration N392GP, collided with the ground and caught fire while maneuvering for landing during an external-load flight at Birchwood Airport (BCV), Chugiak, Alaska. The commercial pilot was fatally injured, and the helicopter was destroyed by ground impact and postimpact fire. Operated by Global Positioning Services, Inc., under 14 CFR Part 133 with no flight plan filed, the flight departed BCV about 1315 in visual meteorological conditions.
According to the operator's representative, the pilot had been conducting practice flights with a 150-foot long-line attached to a fluid-filled, 55-gallon barrel in preparation for an upcoming project. Satellite flight-following data showed the flight remained within 5 nautical miles of the airport, maneuvering near the airport and northeast along the coast of Knik Arm.
Several witnesses saw the helicopter with the barrel suspended beneath it. A witness flying his airplane near the airport heard the accident pilot provide position reports over the CTAF about every half mile, beginning from about 5 miles out as the helicopter approached from the north. At the airport, the helicopter hovered over the approach end of runway 20R. The witness heard the accident pilot repeatedly ask a departing airplane, "Did you hear me?" with no response. Both the witness and another on the ground said the departing airplane appeared to pass close to the hovering helicopter.
The witness in the airplane intended to land on runway 20R, so he maneuvered to wait for the helicopter to clear. As the helicopter transitioned east toward the ramp, he asked the helicopter pilot his intentions. The pilot responded "landing," then a "click" was heard, and the helicopter suddenly pitched nose-up, rolled over to the left, descended, and crashed. The passenger in the witness airplane described the pitch as "way nose up," followed by a left roll and near-vertical descent.
Multiple ground witnesses reported hearing "pop" or "bang" noises. One witness in a hangar adjacent to the accident site reported a high-pitch engine sound followed by two loud "bang" noises seconds apart. When he looked, he saw the helicopter on the ground in flames.
Personnel Information
The pilot held a commercial pilot certificate with a rotorcraft helicopter rating and a second-class FAA medical certificate issued April 1, 2014, with the limitation "must wear corrective lenses." His most recent flight review was completed in the Robinson R-44 on July 1, 2013. As of May 23, 2014, he had accumulated 2,174 hours total flight time, including 2,061.3 hours pilot-in-command, all in helicopters. All flight time recorded in his logbook (beginning April 30, 2010, with 656.5 total hours) was in Robinson R-44 helicopters, primarily the accident helicopter. He completed a Robinson Helicopter Company pilot safety course and R-44 flight training in November 2008.
In the 90 days before the accident, the pilot accumulated 59.5 hours, with most flights involving proficiency practice such as autorotations, hover maneuvers, and flights with a 50-, 100-, or 150-foot long-line. He had conducted seven flights (including the accident flight) with a 150-foot long-line in the accident helicopter in the 2 weeks before the accident.
According to his spouse, the day of the accident was normal. She reported he typically slept about 8 hours per night, went to bed before 2300, and awoke about 0630. She recalled nothing abnormal about his schedule or sleep. He was interested in being proficient with the long-line for an upcoming project involving lowering an all-terrain-vehicle (ATV). She said he researched how the barrel swings, studying how a weighted string reacts to motion, describing his interest as excitement, not concern.
She described the pilot as dedicated to fitness and healthy, with no recent health concerns other than mild cold- or pollen-related symptoms that had cleared. She stated he did not have a cardiologist, only a primary care physician. She recalled a heart-related "scare" 3 or 4 years prior, with testing that may have been misread and required follow-up, but could not recall specifics. He had regular follow-up screenings from his primary physician.
Aircraft Information
The helicopter was equipped with a Lycoming IO-540-AE1A5 engine. The most recent engine log entry, March 14, 2014, documented a 50-hour inspection, oil and filter change, oil screen check, and Hobbs meter replacement; engine time since overhaul was 120.2 hours. The most recent airframe log entry, May 12, 2014, documented installation of new position lights and adjustment of left helipod brackets; airframe total time was 2,339.4 hours.
The engine was overhauled to factory new limits on April 26, 2013, at 2,200 hours. A maintenance record dated June 18, 2013, recorded installation of the overhauled engine at airframe total time 2,166.8 hours; other maintenance included overhaul of the Onboard Systems International cargo hook, model 528-023-01.
Meteorological Information
The closest official weather observation station at BCV reported at 1416: wind from 300° at 3 knots, visibility 10 miles, sky clear, temperature 57°F, dew point 43°F. FAA weather camera images for BCV from about 7 minutes before to 1 minute after the accident showed clouds present with no visibility restrictions below them. Rising terrain and a 4,400-ft peak southeast were identifiable. None of the cameras captured the accident helicopter.
Airport Information
Birchwood Airport (BCV) has two parallel runways. The helicopter was equipped with a Lycoming IO-540-AE1A5 engine (duplicate text in source; omitted).
Wreckage and Impact Information
The fuselage came to rest on its left side on a gravel area south of the paved ramp, with most of the cockpit and cabin consumed by fire. The engine and skids were on the ground near the fuselage with thermal damage. The tailcone and tail rotor were primarily intact aft of the burned fuselage, which faced northwest. A linear scar adjacent to the fuselage was consistent with a main rotor blade length. The main rotor gearbox and mast assembly with hub was found separated about 100 ft north of the fuselage and engine, at the edge of the paved ramp adjacent to a separated taxiway light. One main rotor blade was separated outboard of the hub near the root; the other was attached and damaged. All separated blade pieces were at the site.
The practice barrel was found on its side in the grass adjacent to the ramp. It was about three-quarters filled with water. The long-line was attached to the barrel; the other end was not attached to the helicopter's cargo hook. The line extended from the barrel southwest toward the main wreckage and looped on the ground about 20 ft southwest of the wreckage. Visual examination revealed no scrape, drag, or contact marks uniquely associated with the accident.
The long-line consisted of three 50-foot sections of 3/8-inch braided nylon rope with rope thimbles spliced at each end, connected by aluminum carabiners with locking gates. The barrel end attached to a hook via two carabiners and a swivel adapter; the hook was attached to a barrel harness. The helicopter end terminated at a thimble with no ring or other rigging.
Postaccident examination revealed extensive impact damage to the upper and left airframe. The main rotor drive shaft was crushed and bent about 15° at the teeter stop. Three D212-1 hydraulic servos were removed for further examination.
One main rotor blade was attached to the root and fractured in two places, with segments attached by trailing edge doublers. The separated surfaces were angular and jagged. The blade was bowed upward about 6 ft outboard of the hub, and the outboard 6 ft were bent forward in the direction of rotation. The leading edge had many small dents with coarse chordwise scuff marks. There was a large puncture in the blade afterbody. The other main rotor blade separated near the root, with angular and jagged separations. Both sides of the disconnect had corresponding coarse chordwise scuff marks on the upper skin. This blade was bent forward at mid-span, and the afterbody was fractured from the trailing edge toward the spar. The surfaces were angular and jagged. The leading edge at the tip had coarse chordwise scuff marks; the trailing edge was deformed.
The tailcone sustained thermal damage at the forward end and separated from the upper frame. The intermediate flex coupling was mostly consumed by fire along with the forward tail rotor driveshaft. The tail rotor driveshaft was bowed slightly. The tail rotor driveshaft damper bearing rotated smoothly; the hanger bracket functioned freely. The aft flex coupling was undamaged. The tail rotor gearbox input gear and cartridge separated from the housing and remained attached to the bulkhead; the surface was angular and jagged. The input gear rotated smoothly with no tooth damage; output gear undamaged. Output shaft bent. Blue oil was present around the gearbox. The tail rotor hub and both blades had coarse scuff marks on their outboard surfaces. One blade was slightly deformed along the trailing edge; the other had a dent in the leading edge.
Landing gear sustained only thermal damage. The rear cross tube, rear elbows, and most of the forward cross tube were consumed by fire. The bottom surface of the tail skid had a fresh scrape mark.
The clutch strut was found attached at one end and retained for examination.
Engine examination revealed extensive thermal damage. All accessories were partially or fully consumed by fire; both oil coolers and the oil sump were consumed. The crankshaft could be rotated; valve continuity was established. Compression was observed on cylinders 1, 2, 4, 5, and 6. During the check, debris blew out the intake for cylinder 3, and the No. 3 intake tube was displaced. The oil pump turned freely. Spark plugs showed normal wear. Oil filter and strainer showed no metallic debris.
The operating components of the cargo hook were found separated, some fragmented and encased in molten metal, precluding functional testing. The pilot's cyclic grip with the cargo hook release button mount was thermally damaged.
Medical and Pathological Information
The State of Alaska Medical Examiner's Office performed an autopsy, listing the cause of death as "multiple blunt force injuries" and noting thermal injuries were postmortem. The report also noted focal areas of greater than 75% atherosclerotic stenosis in the mid left anterior descending coronary artery and distal right coronary artery; other coronary arteries showed scattered calcific atherosclerosis without significant stenosis. Focal white scarring in the posterior left ventricle was consistent with a remote myocardial infarct. Microscopic evaluation identified "confluent fibrosis consistent with remote infarct."
Forensic toxicology by the FAA Bioaeronautical Sciences Research Laboratory detected no carbon monoxide in blood, no ethanol in vitreous, and 33.4 ug/ml salicylate (a metabolite of aspirin) in urine.
Medical history from the pilot's primary care physician: In March 2011, a coronary calcium score test showed a total score of 919 (right coronary 361, left anterior descending 335). A total score over 400 indicates very high likelihood of significant atherosclerosis in at least one main coronary artery. A stress test on March 25, 2011, exercised to 14.9 metabolic equivalents without symptoms; the ECG showed non-diagnostic ST segment depression inferiorly at peak heart rate and during recovery. A note suggested a thallium stress test, but no radiology report was in the record.
On March 6, 2012, blood pressure was 142/80. On April 30, 2013, physical examination was unremarkable. A letter from the physician described an elevated glucose level, but no laboratory results specifying the level were in the record.
A 2012 research study found that sensitivity for stress testing for significant stenosis is 77%, even with maximal exertion and nuclear imaging.
Tests and Research
Hydraulic Servos: Visual examination of the three D212-1 hydraulic servos at the Robinson Helicopter factory revealed nominal impact-related damage. Fluid inlet screens were clear; hardware torque stripes unbroken. Functional testing on a factory hydraulic test bench showed all three servos functioned within limits with no anomalies.
Clutch Strut: Examination under magnification at the NTSB Materials Laboratory showed linear scrape damage across one side of the strut fittings at one end.