What happened
On 01 February 2008, a student pilot was conducting training exercises at Wonderboom Aerodrome in a Lazar Helicycle helicopter, registration ZU-EEA. The flight was intended for circuit practice and practicing auto-rotational landings. After completing several successful circuits, the pilot attempted a steep approach from 500 feet above ground level. During this maneuver, the aircraft began experiencing intense vibrations.
In an attempt to stabilize the aircraft, the pilot increased the collective, but the vibration persisted, making instrument readings difficult to read. As the pilot attempted an emergency landing, the engine began to lose power at approximately 100 feet above ground level. During the landing sequence, the pilot flared the aircraft too high, leading to a hard impact. The left-hand skid collapsed upon contact with the grass, causing the main rotor blades to strike the tail boom and sever the tail rotor assembly. The pilot sustained no injuries.
The investigation
SACAA AIID examined the wreckage and the mechanical state of the aircraft. The investigation established that the severe vibrations led to the fracture of two P-clamps that secured the battery box to the airframe. This mechanical failure caused the master key, which was attached to the frame, to be distorted and forced into the "off" position, resulting in the engine stopping.
Investigators also reviewed the aircraft's maintenance and weight records. The Lazar Helicycle was an Experimental Amateur-Built single-seater. While the aircraft was well within its maximum certified mass, investigators noted that there was no recent record of a center of gravity (CG) hang test being performed with the pilot onboard following the change in ownership.
Findings
- The primary cause of the accident was the pilot losing control of the Lazar Helicycle due to severe vibrations during a steep approach and an excessive flare during landing.
- The engine failure was triggered by the fracture of battery box clamps due to intense vibration, which subsequently moved the master switch to the off position.
- A contributing factor was the lack of a verified center of gravity check via a hang test with the pilot onboard, which may have impacted the aircraft's controllability.
- The aircraft sustained extensive damage to the fuselage, undercarriage, main rotor, and tail assembly.