What happened
On 12 September 2002, a BEECH 76, registration ZS-KHG, was conducting a twin-engine conversion training flight near Pretoria. The flight involved a student pilot and an instructor traveling from FAWB to the Pretoria General Flying Training Area No. 2. Before departure, the crew had addressed a starting issue with the left-hand engine involving a magneto inspection, which had been resolved.
While cruising at 8,000 feet, the instructor initiated a single-engine performance demonstration by cutting the fuel mixture to the left-hand engine. Following the student's successful execution of engine-securing procedures, the crew attempted to restart the engine approximately two minutes later. Despite multiple attempts by both the student and the instructor, the left-hand engine failed to restart. As the aircraft lost altitude while flying over the Roodeplaat dam area, the instructor declared an emergency and prepared for a forced landing.
The aircraft descended toward a dirt road in the Kameeldrift area, roughly 7 nm northeast of Wonderboom. Upon touchdown, the aircraft struck a fence and light vegetation, causing it to veer rightward. The momentum carried the aircraft into a sand embankment, where the nose gear detached, causing the aircraft to overturn and come to rest upside down. There were no injuries to the two occupants.
The investigation
SACAA AIID investigators examined the sequence of events leading to the engine failure and the subsequent landing. The investigation focused on the engine's inability to restart following the intentional shutdown for training purposes. The inquiry also reviewed the mechanical history of the left-hand engine, noting the prior maintenance performed on the magneto earlier that day.
Findings
- The primary cause of the emergency was the failure of the left-hand engine to restart following a simulated engine failure intended to demonstrate asymmetric flight and minimum controllable airspeed (VMCA).
- The aircraft was unable to maintain sufficient altitude on the remaining right-hand engine alone.
- The aircraft's excursion from the dirt road was caused by the impact with a fence and bushes during the landing phase.
- The structural damage and inversion of the aircraft were the result of the collision with a sand embankment and the subsequent separation of the nose gear.