What aircraft was involved and where did it happen?

The accident on 1999-04-23 involved a Lac-à-la-Tortue, Quebec, operated by Cessna 172 C-FKHS, at CA.

What was the probable cause of the accident?

The primary cause of the accident was the structural failure of the right stationary panel brace, which jammed the elevator control in a rearward position, preventing the pilot from maintaining control during the go-around maneuver.

Control column jam leads to Cessna 172 crash in Quebec

A flight training exercise ended in a tree impact after a mechanical failure caused the elevator control to jam in the rearward position.

What happened

During a visual flight rules training flight at the Lac-à-la-Tortue airport in Quebec, a Cessna 172, registration C-FKHS, experienced a sudden flight control malfunction. The flight involved a student pilot and an instructor performing a landing exercise on soft ground. As the aircraft approached the runway at low speed with full flaps, the instructor instructed the student to execute a go-around.

Upon applying full throttle and attempting to push the control column forward to gain airspeed, the student found the controls were stuck. Both the student and the instructor were unable to move the column forward. The aircraft subsequently banked to the left and came to rest in a group of trees. There were no injuries to the two occupants, who were able to evacuate the aircraft safely.

The investigation

Investigators examined the cabin of the aircraft and identified a broken right stationary panel brace (part number 0513035-1). This specific component is responsible for providing a rigid attachment for the stationary panel that secures the socket control tube, which facilitates elevator movement. The investigation established that the failure of this brace allowed the stationary panel to move, which obstructed the free movement of the flight controls, particularly when the column was pulled fully to the rear.

Laboratory analysis of the broken brace by the TSB Engineering Branch revealed that the part had suffered a progressive fatigue failure. The fracture surface showed evidence of cracks that developed under reverse bending loads, eventually weakening the part until it separated due to overload. The investigation also noted that the left stationary panel brace had undergone a previous repair in a similar location. Additionally, the investigation found that while the annual inspection had been certified by an aircraft maintenance engineer, the individual items on the inspection form had not been initialed.

Findings

The failure of the right stationary panel brace jammed the elevator control in the full rearward position, causing the aircraft to crash.
Laboratory analysis confirmed the brace failed due to progressive fatigue failure caused by reverse bending loads.
The defect on the stationary panel was visible from the instructor's seat in the cockpit.
The annual inspection records showed that the maintenance engineer had signed the final page of the inspection form, but had not initialed individual line items.