What happened
During a routine circuit training session at Lanseria Aerodrome, a Samba XL aircraft, registration ZU-OHS, experienced a sudden loss of control during an attempted landing. The flight, involving a student pilot and a commercial instructor, was on its third circuit of the morning when the aircraft approached runway 24L. The aircraft was slightly high on its approach with flaps set to the second notch.
As the aircraft drifted toward the left side of the runway, the instructor directed the student to execute a go-around by applying full power. However, as the throttle was advanced, the left wing suddenly dropped and made contact with the runway surface. The instructor attempted to intervene with full right aileron, but the roll could not be arrested. The aircraft subsequently pitched nose-down, veered sharply left, and struck the ground in a shallow trench adjacent to the runway, skidding approximately 25 meters on its fuselage.
The investigation
SACAA AIID investigators examined the aircraft's weight, environmental conditions, and flight dynamics. The investigation established that the aircraft was operating in a non-type certified category. While the wind was within the aircraft's demonstrated crosswind limits, the presence of gusts up to 18 knots likely impacted controllability.
Analysis of the weight and balance revealed that the aircraft was exceeding its maximum takeoff weight at the start of the flight. The combined weight of the instructor and student, including fuel, was calculated at 566.4 kg, surpassing the permitted 540 kg limit. Even after accounting for fuel burned during the flight, the aircraft remained above its maximum allowable weight.
Findings
- The primary cause of the accident was a sudden left roll during the application of full power for a go-around, which led to the left wing striking the runway.
- A significant contributing factor was the wind conditions, specifically gusts from the right that likely aggravated the roll.
- The aircraft was operating in an overweight condition, exceeding its maximum takeoff weight by over 24 kg.
- The weight distribution was affected by the student pilot occupying the left seat.
Safety action
- The investigation noted a recommendation for the SACAA to reconsider the use of Non-Type Certified Aircraft (NTCA) for flight training, citing that the flight envelopes of these aircraft have not been tested to the same standard as Type Certified Aircraft.