The following are the potential hazards near a helicopter:
- Can be nearly invisible – contact whilst they are turning can cause serious injury and death.
- Blowing debris causing pain, discomfort or injury
- Can cause damage to the aircraft, other aircraft or property nearby or, worse still, injury to someone.
- If not carried correctly can hit the turning blades, and could damage the aircraft, damage the item, and even damage someone nearby.
Beware the Blades
A helicopter has two sets of rotor blades:
- The main rotor, the large one on top; and
- The tail rotor, or the smaller one at the rear of the tail.
The greatest threat when operating around a helicopter is the turning rotor blade.
When the blades are turning, the high speed tail rotor is virtually invisible!
Physical contact with either of the blades when they are turning could result in serious or fatal injury
The biggest danger around helicopters are turning blades.
- Be constantly aware
- Do not get complacent
- Do not underestimate the danger
Some helicopters can have a tilt to the rotors when turning.
This means that the rotor blades are at their lowest point right at the front of the helicopter.
Two biggest danger zones:
- At the front of the helicopter
- At the back of the helicopter
- Main Rotor (disc)
- Tail Rotor
Blade sailing can occur when the RPM is low such as when the rotor is starting up or slowing down in strong wind conditions or if the disc experiences a brief gust. With little rotor RPM the centrifugal force is less. If a gust strikes the disc, flap back will occur. The advancing blade will flap up and the retreating blade down. There is now an extreme danger of the blade striking the tail cone. At such low rotor RPM, cyclic inputs are not sufficient to maintain a level disk attitude.
All helicopters are susceptible to blade sailing but two bladed and fully articulated rotor heads will experience it more because of the freedom of movement designed into the rotor head.
Reducing the effects of blade sailing
It may help to have the helicopter parked so that the wind strikes the helicopter 90° from the right. This will mean that as the blade passes over the tail it is climbing and is less likely to strike the tail cone.
Another method of reducing the effects of blade sailing is the use of droop stops.
It is also important to remember that the blades will sail away from a gust of wind as the advancing blade climbs and the retreating blade descends. This means the blades may sail in any direction. So if a pilot is departing the helicopter to the front while the blades are still turning and the blades sail due to a gust of wind from behind there is the real possibility of the pilot being struck by the main rotor.
This is most common when working around other helicopters. One helicopter may be parked and winding down while another is coming into land. The downwash from the arriving helicopter or even the prop-wash from a taxiing aeroplane may cause a gust that produces a blade sail.