History of Flight
The pilot, accompanied by a passenger, was conducting a commercial cargo flight from a gold mine near Welkom to Rand Refinery Heliport in Germiston. Arriving at the heliport, the pilot found helipads P1 and P3 occupied by two other helicopters—a Bell 412 on P1 and another Eurocopter AS 350-B3 on P3. To avoid downwash from the larger Bell 412, the pilot elected to land on helipad P4, which was reportedly seldom used.
While on final approach to P4 at approximately 15 feet above ground level (AGL), a nylon-type industrial bag was blown up by the helicopter's main rotor downwash. The bag collided with the main rotor blades at the 4-5 o'clock position (viewed from above). The pilot did not see the bag before impact.
Damage to Aircraft
The bag strike caused the failure of one of the star-flex beams (red beam) in the main rotor head, resulting in excessive vibration and a control difficulty. A 'CHIP' warning light illuminated on the cockpit annunciator panel, indicating its origin from the main transmission assembly. The pilot executed a forced landing onto helipad P4. The aircraft sustained substantial damage.
Injuries and Other Damage
Neither the pilot nor the passenger sustained injuries. No other damage occurred.
Probable Cause
During final approach for landing at the Rand Refinery helipad, an industrial bag was blown up by the rotor downwash from the helicopter, out of sight of the pilot. The bag struck the main rotor blades, which caused one of the star-flex beams in the main rotor head to fail. This resulted in an excessive vibration accompanied by control difficulty, which necessitated an immediate forced landing.