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Safety News Canada · InteractiveTSB file A25Q0153
The roll they couldn't rule out
A Robinson R44 fell into the woods near Saint-Séverin, Que., leaving investigators almost nothing to read. The TSB can't say why it went down. It does name two hazards any aviation safety program should already be managing.
1Seven minutes out
A whistle nobody could explain
On Sept. 21, 2025, the pilot dropped off his passenger at a private property in Sainte-Marie, Que., and lifted off alone, bound for Magog/Lessard Heliport. The weather was good for visual flight, with no particular turbulence.
About six minutes later, the R44 passed over someone who knew the helicopter. They noticed an unusual high-pitched whistling. Moments after that, a second witness also reported an odd noise.
Then the flight path changed. The helicopter climbed, turned hard right, rotated and dropped into a very steep dive. It struck the treetops and hit the ground. The pilot was killed, and a post-impact fire destroyed the aircraft.
2The flight path
A 295-degree turn, then the trees
Ground-based ADS-B surveillance caught most of the flight. Combined with witness accounts, it shows a helicopter heading southwest that swung right almost all the way around before hitting the trees.
The R44 turned right through 295 degrees before impact
Schematic of the occurrence flight. Numbered points match the list.
- 1Heading for Magog. Track about 230° magnetic after takeoff from Sainte-Marie.
- 2First witness, about 6 minutes in. At about 2,100 feet above sea level (1,000 feet above ground), an unusual high-pitched whistle.
- 3Second witness. Another report of an unusual noise from the helicopter.
- 4Climb and sharp right turn. Peak of 2,475 feet at about 80 knots; witnesses saw the main rotor bank to roughly 90° from the horizon.
- 5Treetops. Steep nose-down, track about 165° magnetic, descending at 30° to the ground.
From about 2,100 feet, it climbed to 2,475 before the dive
Altitude above sea level at the two points the TSB reported. Vertical scale is true; horizontal is not.
3The case file
Investigators were left with more questions than answers
There was no flight recorder. The fire took the cabin, instruments and control connections. The GPS wouldn't power on, and its memory cards gave up no position data. What investigators could confirm mostly ruled things out.
Five open questions still sit in the file
Confirmed
6
- Engine was producing power at impact
- Both rotors were being driven
- Weather not a factor; no turbulence
- Weight and centre of gravity within limits
- Annual inspections done per regulations
- Seized swashplate and mast bearings were in good condition before impact
Lost
4
- Journey log destroyed
- No position data recovered from the GPS
- Cabin, instruments and control connections burned
- All but two cyclic and collective control rods melted
Can't be determined
5
- Source of the whistling noise
- Whether a flight control failed
- Whether a mechanical failure caused the loss of control
- Whether mast bumping occurred in flight
- What role alcohol played in the pilot's performance
4The known hazard
A roll that outruns instinct
Helicopters with a two-bladed, teetering main rotor that turns counterclockwise, as on the Robinson, can snap into a rapid right roll when the rotor is unloaded in low-g flight. On Robinsons with an asymmetrical horizontal stabilizer, that roll comes faster. The TSB says it could explain what witnesses saw.
0
seconds to a 90-degree bank
That's how long it took an R66 to roll onto its side in a 2023 Australian accident, captured in a video released by the Australian Transport Safety Bureau.
40°
bank at 40° per second
55°
bank at 55° per second
Illustration only, not a reconstruction of this flight. Uses the 40 to 55 degrees per second the TSB cites for Robinsons with an asymmetrical stabilizer at higher airspeeds; the indicator shows the faster rate. Real rolls aren't perfectly constant.
The cure runs against instinct. Robinson's Safety Notice SN-11 says the rotor must be reloaded before the cyclic can control the roll. Yank the cyclic left first and the rotor can strike the mast, which is what broke up the Australian R66. Hold off, and the helicopter may still fall several hundred feet before it levels out.
Two Robinsons, same violent right turn, different endings
| R66, Australia, 2023 | R44, Quebec, 2025 | |
|---|---|---|
| Air | Turbulence | No weather conducive to turbulence |
| Speed | 110 to 120 knots indicated | About 80 knots at peak altitude |
| Roll | To 90° in 2 seconds | Rotor banked about 90°, per witnesses |
| Mast | Broke up in flight | Didn't break up; bumping undetermined |
Turbulence isn't required. The TSB notes a strong forward push on the cyclic can produce the same low-g roll in smooth air, and a tight descending right turn fits the start of a spiral dive.
5The paper trail
Three decades of warnings, and a fix still rolling out
The low-g right roll is among the best-documented hazards in light helicopters. A design change aimed at it reached the R44 only in 2024, and older aircraft need a retrofit.
- 1996
A series of 34 R22 and R44 accidents leads the U.S. NTSB to publish a special investigation report.
- 2010
A TSB report documents low-g concerns, Robinson's limitations and the special FAA training rules for R22 and R44 pilots.
- 2023
The FAA approves Robinson's symmetrical horizontal stabilizer for the R66. It reduces the tendency to roll right in low-g.
- 2024
Approval extends to the R44 and R22. New production gets the stabilizer; Robinson offers a retrofit kit.
- June 2025
The ATSB releases its R66 report and video, plus a safety advisory notice on the asymmetrical stabilizer.
- July 2025
Robinson revises SN-11: low-g is extremely dangerous and pilots must never fly a manoeuvre that could cause it.
- Sept. 21, 2025
C-GMSL, put into service in January 2020, crashes near Saint-Séverin, Que.
- May 2026
Robinson service bulletin warns that not following maintenance procedures on the hydraulic servo-to-swashplate connections can lead to serious injuries and deaths.
- Oct. 28, 2026
The TSB releases its report.
Source: TSB report A25Q0153 and the documents it cites. The report doesn't say whether C-GMSL had the newer stabilizer.
6The finding about the pilot
The pilot was under the influence of alcohol
The coroner's report, based on toxicology, found the pilot was under the influence of alcohol. He held a private helicopter licence issued in 2005 and a valid medical certificate.
The TSB notes that alcohol hits problem solving and the processing of new information hardest, so performance suffers most when something unexpected happens. A sudden roll is exactly that. Without flight data or cabin video, though, investigators couldn't tie his blood alcohol level to what happened in the cockpit.
The law sets two tests, and the clock is only one of them
Canadian Aviation Regulations, s. 602.03: no crew member within 12 hours of a drink, or while under the influence. Try a schedule.
Twelve-hour rule check
Clearing 12 hours doesn't clear the second test. Anyone still under the influence can't fly, whatever the clock says.
7What this means for you
An unsolved crash still carries clear lessons
The TSB closed the file without a cause. For anyone running or relying on helicopter operations, the report still points to work that can be done now.
- Test fitness for duty both ways.Policies and pre-flight checks should cover the 12-hour rule and impairment as separate questions, not one.
- Know what's on your tail.If you own, operate or charter R22, R44 or R66 helicopters, find out whether they carry the symmetrical horizontal stabilizer or the retrofit kit.
- Train the counterintuitive move.Make SN-11 part of recurrent training: avoid low-g manoeuvres, and reload the rotor before using cyclic to stop a right roll.
- Audit the control connections.Confirm maintenance providers have acted on Robinson's May 2026 service bulletin on hydraulic servo-to-swashplate connections.
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Register nowSources and methodology
All figures come from the Transportation Safety Board of Canada's air transportation safety investigation report A25Q0153, released Oct. 28, 2026, and the documents it cites, including Australian Transport Safety Bureau report AO-2023-051, Robinson Helicopter Company Safety Notice SN-11 and Robinson service bulletins SB-119A/SB-45A. The TSB does not assign fault or determine liability.
The flight-path and altitude graphics are schematics drawn from the TSB's description of ADS-B data and witness accounts; they are not to scale and don't show exact positions. The roll illustration multiplies the reaction time you choose by the 40 to 55 degrees per second cited in the report. The 12-hour check applies only the time rule in s. 602.03(a). The pilot's reported total flight hours were left out because the TSB could not confirm them.
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