What happened
On the morning of 18 January 2026, the pilot of a RotorWay Exec 90 amateur-built light helicopter was conducting a local flight from a private property near Tamborine, Queensland, with one passenger on board. The pilot reported that during the hover, in preparation for landing, they experienced a sudden loss of tail rotor authority, followed by the onset of uncontrolled yaw[1] and rotation. To counter, the pilot lowered the collective[2] and set the helicopter down, however the helicopter’s rotation as it contacted the ground caused it to roll over and sustain substantial damage. Neither the pilot nor passenger were injured.
Figure 1: Damaged helicopter after recovery
Source: Operator supplied
Engineering information
The RotorWay Exec 90 is a kit-produced light utility helicopter manufactured by the RotorWay Helicopter Manufacturing Company (formerly RotorWay International) and intended for amateur construction. As-designed, the helicopter has a maximum take-off weight (MTOW) of 680 kg (1,500 lb) and is powered by a horizontally opposed 4-cylinder piston engine delivering 112 kW (150 hp).
The Exec 90 powertrain employed a v-belt system that transferred drive to the tail rotor through a series of 3 belts and 2 idlers, extending from the secondary drive unit adjacent to the engine, through the tail boom, to the tail rotor pulley (Figure 2).
Figure 2: Typical drive system – RotorWay Exec helicopters (Exec 162F shown)
Source: UK Air Accidents Investigation Branch report AAIB-27186 (AAIB Bulletin 8/2022)
At the time of the accident, the helicopter had accumulated 64 hours total time in service. Upon inspection after the accident, evidence of the failure of the centre tail rotor belt was found within the tail boom structure – consistent with the loss of tail rotor effectiveness experienced by the pilot prior to the ground contact. The pilot reported that the tail rotor belt had operated for approximately 30–40 hours since new.
Figure 3: Remnants of a loose / fractured tail rotor drive belt found within the tail boom
Source: Operator supplied, annotated by ATSB
Inspections and service bulletins
The pilot reported that tail rotor belt tension had been checked with the manufacturer’s recommended tool before the flight, and noted that there were no indications of imminent belt failure leading up to the loss of tail rotor drive.
Section 3 (D) of the RotorWay Exec 90 flight manual requires a pre-flight inspection of the tail rotor drive components, including the condition and tension of the drive belts, and includes the caution:
IMPORTANT: New belts will tend to stretch and become loose. Belt tension must be monitored and adjusted frequently until stretching has stopped.
Further, the helicopter kit manufacturer has published several mandatory and advisory service bulletins applicable to the Exec 90 helicopter tail rotor drive system.
| Bulletin number | Publication date | Subject |
| M-07 (mandatory) | 8 September 1992 | Prohibition of certain tail rotor belt makes |
| M-20 (mandatory) | 4 April 2002 | Inspection for proper tail rotor belt routing |
| A-20 (advisory) | 28 November 1994 | Inspection and importance of tail rotor belt tension |
| A-21 (advisory) | 12 May 1995 | Tail rotor belt inspection, tensioning, and temperature monitoring |
| A-25 (advisory) | 21 December 1995 | Cold weather inspection of tail rotor belt tension |
| A-36 (advisory) | 4 April 2002 | Inspection for proper tail rotor belt routing |
Most of these bulletins centred on the importance of regular inspection and checking of tail rotor belt tension, and bulletin A-21 further noted:
Advisory Bulletin A-20 (dated November 28, 1994) stressed the importance of checking the condition and tension of the belts before every flight. Although this may be time consuming, these pre-flight checks are essential to the continued safe operation of your helicopter.
Safety message
RotorWay Exec 90 helicopters (and related types with belt-driven tail rotor systems) have an established sensitivity to tail rotor belt tension, with an operational history of failures associated with improperly tensioned belts.
Pilots, owners and operators of these helicopters are reminded to ensure that all applicable checks, inspections and maintenance activities are carried out on the tail rotor drive system, with particular attention to the tension, condition and service life of the belts.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.