What happened
On the morning of the accident, a Cirrus SR20, registration C-GYPJ, departed from Toronto Buttonville Municipal Airport for a flight to Burlington Airpark, Ontario. The flight followed maintenance work performed on the aircraft earlier that day. Shortly after taking off from Runway 15, the pilot reported an issue and attempted a left turn to return to the airport.
During this maneuver, the aircraft's bank angle increased significantly, causing the nose to drop and the plane to enter a spin. The aircraft, which was estimated to be below 500 feet above ground level, struck the rooftop of a nearby building. A fire broke out following the impact, consuming much of the wreckage. The two fatalities involved were the pilot and the passenger. Approximately 15 minutes after the crash, the rocket from the Cirsson Airframe Parachute System (CAPS) ignited due to the heat of the fire, ricocheting across the roof before landing in a nearby street.
The investigation
Investigators examined the wreckage and the engine, finding that the number 3 cylinder head had separated from the barrel. The failure was attributed to a fatigue crack that developed at the notch created by the steel threads of the barrel. This type of crack is difficult to detect using standard non-destructive testing methods.
Analysis of the flight path suggested that the pilot's attempt to turn back to the airport at a low altitude increased the stall speed, leading to the loss of control. The investigation also noted that the aircraft was not certified for spin recovery. Regarding the aircraft's safety systems, there was no evidence that the pilot attempted to deploy the CAPS, and the low altitude likely would have prevented full deployment regardless.
Findings
- The number 3 cylinder head failed due to fatigue, which caused a reduction in engine power during takeoff.
- The aircraft stalled and entered a spin at an altitude that left no possibility for recovery.
- There is currently no practical, non-destructive method available to test cylinder head threads for the presence of cracks.
- The post-impact fire caused the accidental ignition of the CAPS rocket, presenting a potential risk to first responders.