Accident Overview
On a flight from a logging camp at Kumealon Inlet to Prince Rupert and return, a Robinson R22 helicopter (registration C-FILW, serial number 1457M) failed to arrive at the logging camp. A search located the wreckage in the forest near the intended destination one day later. The helicopter had suffered an in-flight breakup, with one main-rotor blade missing. The pilot was fatally injured during the breakup and found 15 metres from the main wreckage. No fire occurred. The accident happened at approximately 1240 Pacific standard time.
Environmental Conditions
The weather reported at Prince Rupert was suitable for visual flight, with winds at 10 to 18 knots. However, a Boeing 107 helicopter crew reported moderate to severe turbulence with winds of 30 to 40 knots in the area at the time of the accident. They described an unusually sharp turbulence that lifted the entire contents of a coffee cup, noting that such turbulence was uncommon even for a heavy, forgiving helicopter.
Helicopter and Pilot Information
The helicopter was owned and operated by Bear Creek Contracting Ltd., used by the logging manager (the pilot) for local transportation. It was registered for private use. The pilot had approximately 1200 flight hours on Robinson R22 helicopters, had completed required awareness training, and was familiar with the local area. The flight manual restricts operation in surface winds exceeding 25 knots, gust spreads over 15 knots, or moderate-to-extreme turbulence for pilots with less than 200 helicopter hours, less than 50 hours on type, or lacking specific training—conditions that did not apply to this pilot.
Accident Sequence and Wreckage Examination
A pre-flight inspection was conducted before the first leg; the flight to Prince Rupert was normal. Shortly before the estimated accident time, the helicopter was seen flying toward the logging camp. The wreckage debris trail, tree damage, pilot's body location, and helicopter damage indicated an in-flight breakup. No evidence of main-rotor blade strikes on trees was found, but branches above the impact area showed damage inconsistent with rotor blade contact.
Investigators determined that severe turbulence, specifically a down draught, unloaded the rotor system. Damage to droop stops and teeter bumpers from both blades indicated unloading occurred before blade separation. The down draught allowed main-rotor blades to flap and teeter sufficiently to shear droop stops and damage aluminium brackets. Elastomeric bumpers fell out, enabling excessive teetering that overloaded the pitch change rod of the separated blade. The rod broke, causing loss of rotor control. The blade likely pitched down, bending under aerodynamic forces. Uncontrolled blade motion overloaded the rotor system beyond design strength, breaking one coning hinge bolt. The opposing blade's bolt showed impending failure but did not break. The blade with the broken bolt separated.
Imbalance from losing one of two main-rotor blades caused violent shaking. The main-rotor transmission tilted forward, port, aft, and starboard as the mast top was pulled off-centre. The tube-frame structure deformed and broke; the aft cabin fire wall deformed forward, loosening the pilot restraint system. The pilot's body was ejected through the windshield into the path of the remaining blade. The MR CHIP detector caution light likely illuminated due to the breakup.
Findings
Causes and Contributing Factors
The helicopter encountered turbulent air that unloaded the main-rotor system, resulting in damage leading to loss of control. Subsequent forces overloaded and broke one main-rotor blade attachment bolt, causing blade separation. Gross imbalance deformed the main-rotor transmission attachment area, and the helicopter broke up in flight.
Risk Factors
The freewheel unit sprag clutch showed extensive wear and tear, likely because it operated more than 700 hours beyond its time limit. The operator continued operating the helicopter after some component life limits were exceeded. The operator did not incorporate Service Bulletin 78 (nor was required to), which posed a risk of teeter stop failure in severe turbulence.
Subsequent Actions
On 11 March 2004, the Transportation Safety Board of Canada issued an Occurrence Bulletin. On 27 May 2004, Robinson Helicopter Company updated Service Bulletin SB-78A, requesting owners to determine compliance with enhanced teeter stop brackets. The U.S. Federal Aviation Administration planned to issue a Notice of Proposed Rulemaking Airworthiness Directive to mandate the higher-strength brackets.
The Transportation Safety Board released this report on 19 October 2004.