Accident Overview
On the day of the occurrence, a Robinson R22 Beta helicopter, registration C-FVBG, serial number 2534, departed from Manning, Alberta, for a round robin flight to document instrument readings at local natural gas well sites. At approximately 1525 mountain daylight time, the Rescue Coordination Centre in Trenton, Ontario, received an emergency locator transmitter signal from 20 nautical miles west of Manning. The aircraft was located 90 minutes later, having struck the ground on the perimeter of well site 11-6. The pilot sustained fatal injuries, and the helicopter was substantially damaged.
Aircraft and Pilot Information
The helicopter, manufactured in 1994 and imported into Canada in 2000, had accumulated approximately 1318 hours time in service. It was equipped for visual flight rules operations and used primarily to access natural gas field well sites. Records indicated the helicopter was certified, equipped, and maintained in accordance with existing regulations, with no known deficiencies before the first flight. The pilot, a part owner of the company, had approximately 1625 hours of helicopter experience, mostly in R22 and R44 models. On the accident day, he had flown about 2 hours, with 4 hours in the previous 7 days and 7 hours in the preceding 30- and 90-day periods.
Flight Sequence
The pilot set out at 1000 MDT to obtain readings from nine well sites and one gas plant. He contacted company dispatch at 1130 and again at 1440, the latter call indicating that well site 11-6 and the “Buick” gas compression plant remained. He mentioned wind gusts that afternoon but did not specify his location or order of visits. Paperwork from the wreckage confirmed all sites were attended.
Weather Conditions
The closest weather reporting facility was Peace River, Alberta, 40 nautical miles southeast. At 1500, winds were 220°T at 9 knots, visibility 15 statute miles, few clouds at 3500 feet above ground level, temperature minus 4°C, dew point minus 15°C. At 1600, conditions were similar, with temperature minus 3°C and dew point minus 14°C. The graphic area forecast showed no significant weather, though Peace River Airport experienced reduced visibility of 2 statute miles in light snow showers and an overcast ceiling at 2000 feet. Satellite imagery at 1634 showed cloud cover near the accident location. Local pilots described mid- to high-level clouds, no significant winds, and temperatures near freezing. No snow or rain was observed on the wreckage or ground.
Wreckage Examination
The helicopter crashed in the northwest corner of well site 11-6. Several tree tops were struck and broken. A tree approximately 60 feet tall and 35 feet behind the wreckage held a nearly intact tail rotor and tail cone section about 2 feet long. The remainder of the hull was forward, upright, with the engine section deeper in the ground. The bottom of the tail rotor warning stinger was found 40 feet forward and to the right of the main wreckage. The forward portion of the tail boom had two main rotor strike indications, and each main rotor blade had a bent leading edge and paint residue from the tail boom. Most of the windscreen was shattered and spread forward. A tail boom section with the rotating beacon was struck by a main rotor blade and located 50 feet in front of the cabin. The tail rotor drive shaft was 150 feet to the right.
Component Examination
A comprehensive examination at the accident site and later facilities found no mechanical defects that contributed directly to the accident. The alternator, an Electrosystems model ALY-842OLS, had 1318.6 hours in service. It showed no structural damage, but brushes were worn well beyond service limits, with one brush slipped out, resulting in no power output at the time of the accident. The alternator warning light would have illuminated. The pilot's operating handbook required the pilot to turn off non-essential electrical equipment, reset the alternator, and land as soon as practical. The ALT switch, strobe lights, radio/navigation, and cabin heat blower switches were found in the ON position, but their pre-crash positions could not be determined. The alternator was operated on an “on condition” basis with no mandatory inspection interval; it could not be determined when it failed.
Electrical System Analysis
The aircraft electrical system operated at 12 volts. Testing of the tachometer indicator, engine governor, and battery relay showed that with a constant 104% input signal, the tachometer maintained accurate reading down to about 8 volts, then indicated lower as voltage dropped. The engine governor, designed to maintain RPM between 97% and 104%, would command engine speed increase as voltage neared 8 volts. The battery relay could maintain voltage to buses until 1.8 volts. Approximately 48 hours after the crash, battery no-load voltage was 2.5 volts; battery charge state before the accident could not be determined.
Rotor System and Accident Sequence
The R22 has a low-inertia rotor system, which can lose energy quickly when collective is raised and power required exceeds power available, leading to aerodynamic stall and loss of lift if corrective action is not taken. The rotor head incorporates teeter and coning hinges. Examination showed upward bending of one main rotor blade, indicating low rotor speed later in the crash sequence. Damage to trees suggested little rotor rotation prior to ground contact, likely caused by two tail boom strikes. The initiating event could not be determined, but it is most likely the pilot lost control while departing the site; damage patterns are consistent with low rotor speed and erratic blade movement causing main rotor strikes on the tail boom.
Additional Findings
No mechanical malfunction was found that may have initiated or contributed to the accident. Weather was not considered a factor. The alternator failure may have distracted the pilot from a low-rotor-speed situation, but this could not be determined. The pilot was not wearing the available lap-belt/shoulder harness at the time; proper use would have likely lessened his injuries. Postmortem examination and toxicology screening found no indication of incapacitation or physiological factors. The pilot sustained significant injuries to the left side of his torso; the female portion of the seat belt latch was found impacted through a sheet metal panel with a clean entrance hole, indicating the male portion was not attached at impact.
Probable Cause (as stated in the report)
Low rotor speed and an erratic blade movement resulted in two blade strikes on the tail boom and the break up of the helicopter. The reason for the low rotor speed could not be determined.