AAIB investigation to Agusta AW139, G-MCSD
Tail rotor blade fairing and bonding strip detached during flight, offshore from Aberdeen, 6 May 2018.
Summary:
As the helicopter climbed after departure, the crew noticed an unusual vibration. They returned to Aberdeen and it was found that a cable fairing and lightning protection bonding strip was missing from one of the tail rotor blades.
Investigation by the helicopter manufacturer established that the bonding strip had failed due to fatigue and loss of the fairing was a secondary effect .
The manufacturer concluded that the occurrence was not safety related and EASA classified the event as ‘Not-Unsafe’. The requirement for a Detailed Visual Inspection of the bonding strip will be added to extant maintenance tasks and the manufacturer is reviewing the manufacturing process.
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