What happened
During a visual flight rules flight from Calgary International Airport to Villeneuve Airport, the pilot of a Cessna 177RG experienced a sudden drop in engine RPM while climbing through 5,000 feet. Despite attempts to restore power using engine and fuel controls, the engine failed to respond, prompting the pilot to declare an emergency.
While attempting to reach Airdrie, the pilot selected a secondary east-west road for an emergency landing. During the maneuver to align with the road, the pilot encountered power lines and began navigating around them. During this process, the aircraft's stall horn activated, and the plane drifted south of the intended path. The left wing dropped, and the flight controls became unresponsive before the aircraft entered a steep descent. The aircraft struck the ground in a nose-low attitude, causing the nose gear to collapse and the right main wheel to break off. The pilot sustained serious injuries, including crushed vertebrae.
The investigation
Investigators examined the Textron Lycing IO-360A1B6D engine and found that the impulse spring in the magneto had broken. This failure caused the spark timing to retard, leading to a significant loss of power. The TSB Engineering Branch determined the fracture was an environmentally assisted failure.
Further investigation into maintenance records revealed that Airworthiness Directive 78-09-07 R3, which requires periodic inspections of the impulse coupling, had not been complied with. The aircraft's maintenance was being performed by a freelance engineer who had relied on an American publication that omitted this specific AD from its listing.
Additionally, the investigation noted that the pilot did not follow the manufacturer's recommended emergency procedures. Specifically, the pilot did not extend the flaps to lower the stall speed, did not establish the recommended glide speed, and failed to secure the fuel and electrical systems, which created a high risk of fire. The pilot was also not wearing the aircraft's shoulder harness at the time of impact.