Operators of a number of Airbus Helicopters Super Puma variants fitted with certain tail rotor de-icing systems have been advised to check the condition of the equipment following an incident where blades were left damaged following overheating of the unit.
EASA says that in certain conditions, the de-icing system on AS332 helicopters – the C, C1, L and L1 models – can inadvertently be turned on while the aircraft is on the ground without the rotors turning.
In such situations, says EASA in an emergency airworthiness directive, the crew may be unable to detect “fumes or smells” coming from the tail rotor “and… possible damage [to] a tail rotor blade”.
This in turn could “lead to structural damage of tail rotor blades resulting in significant vibrations and reduced control of the helicopter”.
EASA says the overheating incident that triggered its warning took place following operation of the de-icing system in flight and subsequent use of a ground power unit (GPU) with the helicopter.
Analysis suggests a failure of a power supply box led to the inadvertent activation of the system while on the ground.
It advises that inspections of the rotor blades take place whenever the de-icing system has been activated – whether in flight or as a ground test – and a 115V/400Hz GPU applied.