The EU Aviation Safety Agency (EASA) has published an Emergency Airworthiness Directive (AD) regarding AB139 and AW139 helicopters.
An occurrence was reported of smoke and fire ignition in the cockpit of an AW139 helicopter, leading to reduced control. The initial investigation evidence revealed signs of short circuit inside the forward cabin roof ceiling panel, due to chafing of an electrical cable against the rivets of the upper torque tube. It was determined that the chafed electrical cable was not routed in accordance with the applicable production drawings. Investigation is still ongoing to determine the root cause of the event.
This condition, if not detected and corrected, could lead to damage of electrical wiring, possibly resulting in a fire in the forward cabin roof ceiling and consequent loss of control of the helicopter.
To address this potential unsafe condition, Leonardo issued the ASB, to provide inspection instructions.
For the reasons described above, this AD requires a one-time visual inspection of the condition and routing of the electrical cables, the torque tube and the diode, all located inside the forward roof cabin ceiling, and, depending on findings, accomplishment of applicable corrective action(s).
This AD is considered to be an interim action and further AD action may follow.
Source: CAA.