Guidance around preparing a helicopter for flight in winter conditions
A helicopter should not take off with the airframe contaminated by ice or snow that could be ingested into the engine intake, block other intakes or cause damage to the rotor and drive system. Similarly rotor blades should not be contaminated in any way that could affect their performance. If a helicopter is to be parked in the open in cold weather and is likely to be exposed to snow or rain, the following should be fitted:
Instructions for such cold weather procedures should be found in the helicopter’s Flight and Maintenance Manuals.
Whereas for aeroplane operations use of de-icing or anti-icing fluids is a common practice, this is not the case with helicopters. Use of such fluids may only take place in accordance with the helicopter manufacturer’s specific instructions. Alternative methods such as hangaring the helicopter until the snow and ice have cleared are more common practices.
The helicopter’s Flight Manual will specify in the Limitations Section those fuels which are to be permitted. It will also specify under which conditions the fuel should contain an anti-icing additive. These conditions will either be an Outside Air Temperature (OAT) limit or a combination of airframe configuration and an OAT limit, e.g. installation of a fuel filter or ice trap in the fuel supply line can allow exposure to lower temperatures without additives.
When a fuel additive is specified (and it may be at a temperature routinely encountered in flight), it is the operator’s responsibility to ensure it is included. If it is not included in the fuel at delivery, a means to add it should be available. Simply adding neat additives such as FSII to the tank is not acceptable and may lead to damage to tank seals and coating (FSII is an efficient paint stripper). Manufacturers’ guidance as to the method of the addition of anti-icing additives to fuel should be followed closely.
If snow and ice is lying on the ground, there may be a risk of the helicopter yawing on rotor start or stop due to torque reaction. Consideration should be given to moving the helicopter to an uncontaminated area. On take-off, the crew should be aware of the possibility of one skid being stuck to the ground resulting in a dynamic rollover.