The EU Aviation Safety Agency (EASA) has published an Emergency Airworthiness Directive (AD) regarding AW139 helicopters.
An occurrence was reported involving a protruding handle rod pushbutton on the left-hand (LH) cockpit door internal handle, which resulted in an interference with the collective stick travel. Subsequent investigation determined that vibration and/or incorrect torquing may have contributed to the loosening of the pushbutton holding screw of the cockpit door handle, with consequent excitement of the pushbutton from its seat.
This condition, if not detected and corrected, could lead to reduced collective stick authority, possibly resulting in reduced control of the helicopter.
To address this potential unsafe condition, Leonardo S.p.A. issued the ASB (Alert Service Bulletin) to provide inspection and corrective action instructions. For the reasons described above, this AD requires a one-time inspection of each affected part and, depending on findings, corrective actions and reporting.
This AD is considered to be an interim action and further AD action may follow.
Source: EASA via CAA.