Regulations & Safety
AAIB Report Details Leonardo AW139 Tail Rotor Bearing Near-Miss
The AAIB report reveals a severe tail rotor duplex bearing failure on a Leonardo AW139 in 2022, prompting safety recommendations for offshore helicopter operations.
On May 21, 2026, the UK’s Air Accidents Investigation Branch (AAIB) published its final report detailing a severe near-miss incident involving a Leonardo AW139 Helicopters. The aircraft, registered as G-CIMU and operated by CHC Helicopter, suffered a near-catastrophic failure of its tail rotor duplex bearing during offshore passenger flights on June 13, 2022.
According to the official AAIB report, the critical defect was only discovered during a routine post-flight MRO check at Norwich Airport. The helicopter had spent the day transporting passengers to North Sea oil rigs. The findings highlight a severe safety issue, as investigators noted that continued operation would likely have resulted in a complete loss of tail rotor control.
This incident has raised fresh concerns within the aviation industry, drawing stark parallels to the fatal 2018 Leicester City helicopter crash, which involved a similar Leonardo rotorcraft and a comparable bearing failure. In response to the findings, the AAIB has issued three new safety recommendations.
The Incident and Investigation Findings
Routine Inspection Averts Disaster
The incident on June 13, 2022, involved a Leonardo AW139 flying offshore routes from Norwich Airport. Upon returning to base, maintenance engineers conducting a standard post-flight inspection noticed a glaring anomaly: a hole had worn completely through the protective bearing and actuator cover over the tail rotor duplex bearing assembly.
When personnel removed the cover, they discovered extensive internal damage. The AAIB report details that the assembly contained exposed ball bearings, heavy wear, and significant accumulations of carbon dust. The degradation was so severe that the bearing completely disintegrated when engineers attempted to remove it from the aircraft.
AAIB Conclusions and Safety Recommendations
Despite a comprehensive forensic assessment by investigators, the exact root cause of the initial failure remains inconclusive because the bearing was too badly damaged and degraded. However, the AAIB was unequivocal about the potential consequences of the mechanical fault.
“A loss of tail rotor control event would likely have occurred had the helicopter continued to operate with the bearing fitted,” the AAIB stated in its official report.
In response to these alarming findings, the AAIB has issued three specific Safety Recommendations. According to the agency, these measures are aimed at addressing ongoing Safety concerns related to the failure of tail rotor duplex bearings across the AW139 fleet.
Historical Context and Industry Impact
Echoes of the 2018 Leicester City Tragedy
The failure mechanism identified in the G-CIMU incident closely mirrors one of the most high-profile helicopter accidents in recent UK history. On October 27, 2018, a Leonardo AW169 helicopter crashed outside the King Power Stadium, resulting in the deaths of all five people on board, including Leicester City Football Club owner Vichai Srivaddhanaprabha.
The AAIB’s Investigation into the 2018 fatal crash concluded that the root cause was the failure of the tail rotor control system, specifically the tail rotor duplex bearing. According to the latest AAIB report, the bearing on the AW139 is defined as a “critical part” and shares a similar design with the component that failed on the AW169.
AirPro News analysis
At AirPro News, we observe that the recurrence of a tail rotor duplex bearing failure, four years after the Leicester City tragedy, highlights a persistent engineering vulnerability within this family of Leonardo rotorcraft. The fact that this 2022 incident occurred on a passenger-carrying offshore flight underscores the critical reliance on rigorous maintenance protocols.
The offshore helicopter industry operates in notoriously harsh environments over the North Sea, where component stress is high. This near-miss scenario demonstrates that while engineering flaws may still exist, strict adherence to post-flight inspections serves as a vital, life-saving safety net. Industry reporting, including recent coverage by aviation journalist Joanna Bailey, indicates that these findings will likely prompt operators to scrutinize tail rotor assemblies even more closely to prevent future catastrophic failures.
Frequently Asked Questions (FAQ)
What caused the Leonardo AW139 tail rotor bearing failure?
According to the AAIB, the exact root cause of the initial failure is inconclusive because the bearing was too severely damaged and degraded by the time it was inspected. However, investigators found exposed ball bearings, heavy wear, and large accumulations of carbon dust.
Was anyone injured in the June 2022 incident?
No. The helicopter safely completed its passenger flights to North Sea oil rigs and returned to Norwich Airport. The severe damage was discovered during a routine post-flight maintenance check, preventing a potential in-flight disaster.
How does this relate to the 2018 Leicester City helicopter crash?
The 2018 crash of a Leonardo AW169 was caused by the failure of its tail rotor duplex bearing. The AAIB notes that the bearing on the AW139 is a “critical part” of a similar design, highlighting a recurring engineering concern across these aircraft models.
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Photo Credit: AAIB