The pilot and the helicopter were involved in a training exercise for trainee fireman. The task was to teach safety around helicopters, especially relating to fire fighting activities. The State Fire Commission provided new sling equipment, purchased from a ship chandler. Experienced fire fighting personnel had prepared several sling loads in advance for the pilot. The strop chosen to lift the 500kg water bladder was 20 metres long. The purpose of the long strop was to enable the helicopter to lower the water bladder to firemen working in low scrub. The strop had been assembled by passing each end of the rope around a metal eyelet and whipping it because the polyester rope was not suitable for splicing. Visually the whipped ends looked satisfactory.
The helicopter lifted the load to about 150 feet above the ground and was accelerating through about 20 knots when the pilot heard a loud bang, felt a vibration through the airframe and realised that the load had detached from the helicopter. He made a precautionary landing nearby. The rope of the strop had slipped through the whipped section at the eyelet where it attached to the water bladder with a shackle. The rope had recoiled, damaged one of the three main rotor blades, ripped the right hand horizontal stabilizer and wrapped around the tail boom.
The known safe working load limits for the individual items comprising the strop were more than adequate for the intended sling loads. The new strop had never been proof tested; nor was there any indication that the helicopter company or the Fire Commission had instructed the manufacturer to proof test the strops.