Summary
We propose to adopt a new airworthiness directive (AD) for Airbus Helicopters Model AS355NP helicopters with certain fire extinguishing systems. This proposed AD would require removing and installing the fire extinguishing system so that each squib on the engine compartment fire extinguisher is controlled by a matching control button. This proposed AD is prompted by the discovery that the left-hand discharge system of the fire extinguishing system was incorrectly connected to the right-hand engine compartment and the right-hand discharge system was incorrectly connected to the left-hand engine compartment. The proposed actions would correct the connections and would prevent the fire extinguishing system discharging to the wrong engine compartment, failure of the fire extinguishing system to control a fire, and subsequent loss of control of the helicopter.