Firefighting Bucket Snags Trees During Autorotation

Posted by on Mar 6, 2025 in Accidents & Incidents, Helicopters, Human Factors / Performance, Safety Management, Special Mission Aircraft | 0 comments

Firefighting Bucket Snags Trees During Autorotation (Valhalla Helicopters Bell 205 C-GRUV)

On 19 July 2023, Valhalla Helicopters Bell 205A-1 C-GRUV crashed while conducting firefighting in northern Alberta.  The pilot died of his injuries.

Wreckage of Valhalla Helicopters B205 C-GRUV (Credit: RCMP)

The Transportation Safety Board of Canada (TSB) published their safety investigation report on 27 February 2025.

The Accident Flight

At 1803 Local Time, 9 minutes after being tasked, the helicopter departed Haig Lake firebase, Alberta, on a VFR flight to a forest fire located approximately 15 NM northeast of Peace River Aerodrome Alberta.  The helicopter had an empty firefighting bucket, a1230 l SEI Industries Bambi Bucket BB2732, on a 150-foot longline.

The pilot had 8711 flying hours total time, 3286 on type and a further 2048 on the B212.

The helicopter was powered by an Ozark Aeroworks (formerly Honeywell) T5317B.

Very shortly after departure, after reaching 1400 ft AGL, the helicopter experienced an engine failure.

The helicopter began a 180° turn to the right, to a heading of approximately 025° magnetic, during which it continued to lose altitude. The helicopter then experienced a complete loss of engine power and the pilot began to autorotate into a section of muskeg to the west of his current location.

Flight Path of Valhalla Helicopters B205 C-GRUV (Credit: via TSB)

During the subsequent autorotation the water bucket became entangled in trees.

Accident Site of Valhalla Helicopters B205 C-GRUV (Credit: RCMP/TSB)

The helicopter consequently impacted the ground in a nose-down, left-banked attitude.  The main rotor struck the tail boom.  The damage indicated low rotor rpm at the time of impact.  There was no post-impact fire. The pilot survived the initial impact and was able to egress from the helicopter but later died of his injuries.

The Safety Investigation

The helicopter was not equipped with a flight data recorder or a cockpit voice recorder.  Neither were required by regulation.  The helicopter’s Garmin GPSMAP 496 provided the investigation with information about its flight path.

T53 Engine (Credit: Honeywell)

A teardown of the T53 engine determined that a failure of the engine air diffuser’s No. 2 bearing support cone brazing resulted in the compressor rotor making contact with the power shaft, resulting in a high level of damage and vibration. 

The failure of the brazing was due to an undetermined manufacturing defect that created a localized stress concentration that, over time, resulted in the progressive failure of the braze bond.

The helicopter was equipped with an Onboard Systems keeperless cargo hook kit rated for loads up to 5000 lbs.  Investigators found the longline wrapped around treetops in the vicinity of the impact site.

The snagged water bucket resulted in forward momentum being translated to a circular acceleration vector toward the ground, increasing the helicopter’s rate of descent.

To counteract this, the pilot likely pulled aft on the cyclic and increased the collective to arrest the descent. With the engine no longer producing power, these actions would have led to a decay in main rotor rpm in the final moments of flight.

The main rotor blades slowed to the point that the main rotor rpm would not have been recoverable. As the main rotor slowed, the retreating blade (left side) would have stalled, causing a roll to the left and a pitch forward in the final seconds before impact.

For unknown reasons, the pilot did not jettison the external load using either the electrical or the manual release methods at the beginning of the autorotation.

The pilot could have initiated a load release by either pressing for 2-3 seconds the electric cargo release push button on the cyclic or by using the manual release pedal.

The manual release pedal is located on the floor between the anti-torque pedals.

B205 Manual Cargo Release Pedal (Credit: TSB)

According to the rotorcraft flight manual supplement, in an emergency, such as a snagged load or engine failure, the manual release system should be the first option used to release the external load, as this system provides greater load release authority in overload conditions. If the manual release option fails, the electric release should be tried next.

However, in an emergency, using the manual release requires the helicopter pilot to momentarily remove a foot from a primary flight control. This may be difficult to accomplish successfully during manoeuvres that require constant input from the pilot, such as an autorotation.

The electrical release (below) is armed by a 2-way locking CARGO REL (cargo release) switch on the overhead panel.  Arming is indicated by the RELEASE ARMED annunciator on the instrument panel.  Investigators found the CARGO REL switch was off. 

Electric cargo release push button on the cyclic from B205 C-GRUV (Credit: TSB)

Notably: 

TSB discussions with other helicopter operators indicate that it appears to be an industry norm to not place the CARGO REL switch in the ARM position in order to prevent an accidental electric release. This is likely because there is a perception that sufficient time would be available to either arm and then press the electric switch or activate the manual release, if required.

The pilot was rated for both the B205 and the B212.

TSB note that the procedures differed between B205 and B212. For the B205, the CARGO REL switch is to be set to ARM for electrical release, with no further guidance given.  In the B212 RFM Supplement, the CARGO REL switch is set to the ARM position for takeoff and landing and set to the OFF position for in-flight operations.

TSB do not elaborate further but note that:

To re-arm the electric release, the pilot would have had to either remove his right hand from the cyclic or his left hand from the collective and reach up above his body to the overhead panel to move the CARGO REL switch. These options would have been very difficult during the high workload and given the precision required for a successful autorotation.

The investigators note that the Canadian Aviation Regulations (CARs) require both emergency training and external load training…

….however they do not specifically stipulate a requirement for conducting training of emergencies unrelated to external load equipment while conducting Class B and C external load training.

Contact with two other air operators with similar fleets revealed that…

…neither had conducted standard emergency procedures training while conducting external load operations. Moreover, almost none of their pilots had ever attempted to activate the manual cargo release in flight, let alone during an autorotation.

TSB note that:

Without practising an emergency procedure, such as an external load release, in a controlled environment, it is not realistic to expect a pilot to effectively perform it during an actual emergency. The development of motor skills during training involves progressing from understanding basic components to refining and eventually automating the skill. This process highlights the importance of initial and recurrent training to maintain proficiency and ensure that critical skills remain second nature, particularly for tasks that are infrequently performed but are crucial for safety during an emergency.

Valhalla’s website states that:

In 2006, Valhalla Helicopters developed a comprehensive and customized Safety Management System, encompassing all aspects of health, safety and environment exceeding the requirements of Transport Canada and meeting or exceeding the requirements of the oil & gas industry.

No mention of their SMS is made by TSB, including any risk assessments on firefighting operations.  

Safety Action

After the occurrence, Valhalla Helicopters issued a company memo reminding flight crews that the electric cargo hook be armed for any external load operations and that both the manual and electric releases be checked before the 1st flight of the day.

No safety recommendations were made by TSB.

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.  You may also find these Aerossurance articles of interest:

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