AW139 Tail Rotor Duplex Bearing Failure at Norwich Prompts AAIB Safety Recommendations
Impact Assessment Rationale
The incident directly affects the AW139 fleet globally, particularly offshore oil rig operations where tail rotor control loss in hover is high risk; while no hull loss occurred, the safety recommendations and regulatory dispute could drive significant airworthiness compliance costs and affect insurability of the broader fleet.
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Summary
A collapsed tail rotor duplex bearing was discovered during post-flight maintenance on a Bristow Helicopters AW139 (G-CIMU) at Norwich Airport on 13 June 2022. The AAIB determined that a loss of tail rotor control would likely have occurred had the helicopter continued operating, drawing parallels to the fatal 2018 Leicester City AW169 crash. The investigation revealed the bearing had been improperly refitted contrary to maintenance manual instructions. The AAIB has issued safety recommendations to Leonardo Helicopters for enhanced inspection regimes and HUMS upgrades, facing opposition from Italy's ANSV regulator.
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Structured Intelligence
known
- Collapsed tail rotor duplex bearing discovered on Bristow Helicopters AW139 (G-CIMU) during post-flight maintenance at Norwich Airport on 13 June 2022
- AAIB confirmed loss of tail rotor control would likely have occurred had the aircraft continued operating
- Bearing had been improperly refitted contrary to approved maintenance manual instructions, accumulating 1,007h before refitting and a further 1,743h before failure was identified
- HUMS failed to flag real-time warning signs, though retrospective analysis showed a changing relationship between airspeed and pedal position from approximately 7 June 2022
- AAIB has issued recommendations to Leonardo Helicopters for comprehensive inspection programme and HUMS enhancements
- The AW139 fleet did not receive safety measures introduced for AW169 and AW189 following the 2018 Leicester City crash
reported
- Pilots noted foot pedals 'felt a bit strange' on preceding flights but did not consider it a serious concern
- Italy's ANSV civil aviation regulator disputes both the safety recommendations and the classification of the event as a 'serious incident'
uncertain
- Whether the failure mechanism on the AW139 is the same as that which caused the AW169 Leicester City crash has not been proven
- Whether existing mitigation actions for the AW139 fleet are adequate to address the airworthiness risk remains disputed between AAIB, Leonardo, and EASA/ANSV
Affected Countries
Key Entities
Sources
Trade Media
- FlightGlobal22 May 2026, 14:24
Timeline
Status changed to monitoring
Auto-transitioned: no updates for 6 hours
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active → monitoring
Status changed to active
remediation: existing authoritative signal
Lifecycle changed
signal → active
Initial Detection
A collapsed tail rotor duplex bearing was discovered during post-flight maintenance on a Bristow Helicopters AW139 (G-CIMU) at Norwich Airport on 13 June 2022. The AAIB determined that a loss of tail rotor control would likely have occurred had the helicopter continued operating, drawing parallels to the fatal 2018 Leicester City AW169 crash. The investigation revealed the bearing had been improperly refitted contrary to maintenance manual instructions. The AAIB has issued safety recommendations to Leonardo Helicopters for enhanced inspection regimes and HUMS upgrades, facing opposition from Italy's ANSV regulator.
The extent of the damage to the bearing confirmed that a loss of tail rotor control event would likely have occurred had the helicopter continued to operate with the bearing fitted.
Source: FlightGlobal (Trade Media) · View source