Frequestly Asked Questions

What Makes Helicopters Fly?
Are Helicopters Safe?
Some Helicopters Look So Fragile!
Are Helicopters Expensive?
What Kinds of Fuel do Helicopters Use?
Are Engines Reliable?
What Happens if the Engine Fails?
What are the Effects of Altitude and Temperature?
What are Weight and Balance Limitations?
What Other Limitations Does the Helicopter Have?
What is the Responsibility and Authority of the Pilot?
What Safety Responsibilities Do I Have as a User or Passenger?
Can Helicopters Fly in Bad Weather?
Do Helicopters Need A Lot of Maintenance?
How Affordable are Helicopters?
What about Helicopter Noise?
Summary

What Makes Helicopters Fly?

A helicopter is lifted into the air by the same principle through which an airplane takes off from the ground: the movement of an airfoil through air. The wing of an airplane is an airfoil, which is moved through the air with the forward movement of the entire aircraft. The rotor blades of a helicopter are also airfoils, which are moved through the air in a circular motion without requiring any movement of the helicopter itself. As air flows over an airfoil, a pressure differential is created. The pressure on the top surface of the airfoil is less than the pressure exerted on the bottom, due to higher speed of the airflow over the top. This results in a lifting force.
When the lift created exceeds the weight of the aircraft, flight is achieved. The main rotor of a helicopter is controlled by the "cyclic," a control held in the pilot's right hand. Using the cyclic, the pilot is able to tilt the main rotor in any direction he or she wants the helicopter to fly. Tilting the main rotor converts part of the main rotor disc's lift into lateral thrust, allowing the helicopter to move in the desired direction. As the rotor disc is tilted more and power is added, thrust increases, and the helicopter moves faster in that direction. By gently pulling back on the cyclic, speed decreases, and by centering the cyclic to compensate for any wind, the pilot is able to hover over a point. By pulling further back on the cyclic, the helicopter will fly backward. Helicopter movements involve other controls as well. The "collective" control, held in the pilot's left hand, increases or decreases the pitch (angle) of the main rotor blades uniformly. The upward or downward collective movement also increases or decreases engine power and thrust to the rotor system. A throttle may be placed overhead or on the collective to set or control engine R.P.M. In most small helicopters, a manual throttle is placed on the collective and continuously controlled by the pilot.
The tail rotor is used to counteract the force (torque) required to turn the main rotor and to keep the helicopter from spinning in the opposite direction. To do this, the pilot applies right/left pedal pressure as power is increased or decreased. This causes the tail rotor to produce more or less thrust as needed for directional control. The tail rotor also allows the pilot to turn the helicopter while hovering and provides some of the directional control during forward flight.
Some manufacturers put two main rotors on the helicopter in either a tandem or coaxial configuration. Two main rotors on a helicopter turn in opposite directions, each counteracting the force (torque) required to turn the other. This eliminates the need for a tail rotor. Movement of the aircraft is achieved by coordinated movements of the two rotor systems through mechanical or hydraulic linkages activated by control movements very similar to those described above.
Another method of "tail rotor-less" directional control is achieved by what is called the coanda effect. A fan in the rear of the helicopter forces air through the tail section and out though slots or louvers on one side of the tail. This produces higher speed airflow on one side of the tail than on the other. The force generating lift or thrust is similar to the airfoil discussed earlier. This method gives excellent directional control with no moving parts on the exterior of the helicopter.

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Are Helicopters Safe?

Helicopters have evolved rapidly since the first controllable US. Helicopter was designed and flown by Igor Sikorsky in 1939. Since then, reliability and performance capabilities have increased dramatically. Helicopters have been adapted to perform a myriad of difficult tasks that may have surpassed the dreams of the visionaries, Igor Sikorsky and Lawrence Bell, the designer of the first Bell helicopters, and others who have designed the helicopters of today, from the simplest to the most advanced aircraft.
Even though helicopters are used to perform numerous, unique, and often difficult missions, helicopters have achieved levels of safety many thought impossible twenty years ago. According to National Transportation Safety Board and Federal Aviation Administration statistical data, helicopters now appear to be one of the safest forms of light aircraft. The number of accidents dropped from 30 per 100,000 flight hours in 1970 to slightly over 9 in 2002.
Helicopters have the ability to land safely in very small areas, even in an emergency such as an engine failure. The ability to "autorotate" (land without engine power,), combined with regular emergency training for pilots and improved crashworthiness, account for the helicopters remarkable safety record.

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Some Helicopters Look So Fragile!

To keep the helicopter light and achieve the maximum useful load, components are made as light as possible while maintaining structural integrity. Doors and windows, for example, are built of light material and should be treated gently. On the other hand, rotor blades, transmissions and other components whose functions are essential to safe flight are designed to be stronger than necessary by a wide margin.

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Are Helicopters Expensive?

The small piston engine helicopters used commercially sell for slightly over €180,000, or about 30% - 50% more than the cost of a similar size airplane. Turbine powered helicopters range from about €1,000,000 for a four-passenger model to several million dollars for the medium twin-engine helicopters. Any new aircraft, including helicopters, have extensive engineering, development and Aviation Administration certification costs, which must be absorbed through the sales price of the relatively small number of helicopters sold. The complexity and the need for exceptional reliability make helicopters more expensive than airplanes of equal size. In recent years, new technology has greatly simplified helicopter design, adding to its reliability.

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What Kinds of Fuel do Helicopters Use?

Many modem helicopters are turbine powered. All turbine helicopters burn a kerosene-type aviation fuel such as Jet-A. Many old, as well as some new helicopters are powered by reciprocating (piston) engines and use a grade of aviation gasoline (Avgas) refined especially for aircraft engines.

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Are Engines Reliable?

Turbine engines generally require less frequent maintenance then piston engines and they have the advantage of developing much more horsepower per pound of engine weight. Turbine engines have made the modern, high performance helicopter possible. Both turbine and reciprocating engines are achieving new levels of reliability and durability.

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What Happens if the Engine Fails?

A single engine helicopter must land if the engine fails, but it is capable of descending safely in a condition of flight known as "autorotation". Helicopter rotor systems are designed so that normal rotor RPM is maintained during a power-off descent. The flow of air upward through the rotor system sustains RPM, allowing the pilot to maintain full control of the helicopter.
Although the ratio of horizontal distance traversed versus loss of altitude is less than that of an airplane, both the helicopter's forward speed and vertical descent rate can be reduced to near zero at touchdown. This ability to literally land on a cent enables the helicopter to gain a major safety advantage over airplanes, which must touch down at relatively higher forward speeds. All pilots must be fully qualified to accomplish safe autorotations as part of their training prior to certification. They also practice either "full touchdown" or "power recovery" autorotations during periodic training sessions, which are mandatory for operators carrying passengers for hire.
A twin-engine helicopter can normally continue to fly to a safe landing area by relying on its second engine. However, the remaining engine might not develop enough power to hover a heavily loaded helicopter. In such cases, a low-speed run-on landing, rather than a vertical touchdown, would usually be made. Twin-engine helicopters can also accomplish full-stop autorotations, if necessary.

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What are the Effects of Altitude and Temperature?

The performance of a helicopter is affected by air density, which is a factor of temperature, altitude, and humidity. This is called "density altitude". Best lift is achieved in dense air, which occurs at sea level with cool temperature and low humidity. As altitude, temperature, or humidity increase, the air gets thinner, and engine limitations are more quickly reached. Airfoils produce less lift in the thinner air, thus reducing efficiency. "Density altitude" is a value calculated by the pilot to indicate the performance he or she can expect from the aircraft and engine, based on the temperature and the actual altitude. Density altitude could be much higher than the actual altitude. For example, a helicopter operated at 7,000 feet above sea level on an unusually hot, humid day may perform as though it were at 10,000 feet above sea level. Higher elevations and/or density altitude may greatly affect lifting/hovering ability, and will limit engine power and top speed of most helicopters.

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What are Weight and Balance Limitations?

Before a new aircraft design is placed into production and made available to the public, certain limits regarding the loading of passengers and cargo are established by the manufacturer and the JAA. These limits determine the maximum gross weight of the aircraft and requirements for passenger and cargo distribution. Some definitions, which may help you understand the terms relating to those limits are as follows:
Empty Weight - The weight of the aircraft with no usable fuel, cargo or passengers on board.
Gross Weight - The actual weight of the aircraft as it is loaded at any given time.
Maximum Allowable Gross Weight- This is the maximum weight at which the aircraft can be flown, as determined by the manufacturer and the JAA. This weight may have been established for structural, aerodynamic or control reasons, but in any case, it is the heaviest weight at which the pilot is allowed to fly the aircraft.
Payload - The actual combined weight of passengers and cargo that can be carried on the aircraft. The weight of the fuel, crew, and any on-board equipment must be subtracted from the useful load to determine available payload.
Center of Gravity (CG) - The manufacturer and the JAA have determined the allowable limits for the CG, which is critical to the safety of every aircraft. The pilot must determine proper loading; weight of passengers and cargo must be known. Improper loading can cause loss of control or less than optimal maneuverability of the aircraft.

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What Other Limitations Does the Helicopter Have?

In addition to airframe limitations affecting the way a helicopter can be loaded, engine manufacturers have established limits on engine performance to guard against premature failure.
Torque - This is the measure of the power developed by the engine that is required to turn the rotors. A limit has been placed on the maximum amount of torque that can be used, so as not to exceed the design limits of the various parts of the engine and the rotors. Depending on the manufacturer, torque gauges may indicate pounds per square inch (PSI) or percent. Some helicopters use a gauge that shows angle of pitch in the main rotor blades, calibrated in degrees or percent, as an indicator of power demand on the engine. In piston engine helicopters, manifold pressure and engine RPM are usually used to indicate the power developed by the engine. In any case, exceeding the limit increases wear and may decrease the life of various components
Engine Temperature - Some of the ways in which engine temperature is indicated are TOT (Turbine Outlet Temperature), EGT (Exhaust Gas Temperature), ITT (Internal Turbine Temperature) or T4. Piston engine helicopters display CHT (Cylinder Head Temperature), and some helicopters ma include engine and transmission oil temperature gauges. Damage done by exceeding temperature limitations does always show up immediately. It can show up many hours later, a factor which makes especially important that any inadvertent overtemp be reported by the pilot to maintenance so that required inspections can be made to check for damage before a failure occurs.
Note: Engine/Rotor Systems Cycles – Engine, transmission, and rotor systems experience increased internal stress with repeated starts and stops. Reliability may be greatly enhanced for turbine engines in remote or on emergency operations by keeping, engine running during loading/unloading with rotors turning. It is important that established procedures be followed and assistance provided to passengers where possible. Aircraft should never be left unattended during these operations.

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What is the Responsibility and Authority of the Pilot?

It is important to understand the extent that the pilot is legally responsible for safety. He/she is a licensed professional as such is given COMMAND of the aircraft. The Joint Aviation Authority makes this clear in the following ways:
"The pilot in command of an aircraft is directly responsible for, and is the final authority as to the operation of that aircraft"
"No person may assault, threaten, intimidate, or interfere with a crewmember in the performance of the crewmember's duties aboard an aircraft being operated"
"Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner or physical indications that the individual is under the influence of drugs (except a medical patient under proper care) to be carried in that aircraft"
Since the pilot is charged with the safety of his passengers and crew, it is important that he/she be given full attention during briefings and be notified of any special requests or conditions.

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What Safety Responsibilities Do I Have as a User or Passenger?

Do not hesitate to ask questions! Careful pre- flight planning with the operator and pilot are essential to a safe flight. If you have special requests, be sure the pilot knows, so that proper fuel can be added or removed. Insist on thorough passenger briefings.
BE ALERT! Do not approach the helicopter until instructed, and then only from the front or side and in view of the pilot. Never drive a vehicle under the rotor blades - they are closer to the ground than you might think. Use extreme caution and lower your head when walking under the main rotors.
Never lift your arms or carry long objects that might be hit by rotor blades. Approach from the downhill side - never uphill because rotors may be only a few feet above the surface, and they may flex downward, especially during shut down. Stay away from tail rotors and never approach the rear of the helicopter unassisted. Tail rotors are dangerous and difficult to see.
Never touch the controls of the helicopter or hurriedly get into the helicopter - especially the front seats. Minor control movements could be disastrous. Use entry steps with caution to avoid slipping or wait for assistance. Never insist that the pilot hover "out of ground effect" (OGE). When the helicopter is flying between 50 feet and 300 feet above the ground, forward airspeed above 20 knots provides the pilot an adequate engine power reserve and also enhances the pilot's ability to complete a safe autorotation in an emergency.
Whenever there is any doubt about the lifting capability of the helicopter, users should off-load passengers or cargo at the direction of the pilot. An extra trip is less costly than an incident.
Passengers should move cautiously, be alert and above all Never Pressure the pilot "to go" when he says it should be a "No-Go" decision. Winds, weather, and hazardous operating conditions or locations must be respected, as should the pilot's judgement.

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Can Helicopters Fly in Bad Weather?

Pilots of helicopters flown under VFR (Visual Flight Rules) are required to maintain sufficient visual references to control the helicopter. Helicopters operated under IFR (Instrument Flight Rules) are properly equipped and certificated to be operated by an instrument-rated pilot without visual references. Helicopters operated under IFR may fly into clouds or other conditions where visual contact with the surface is not maintained. The minimum weather conditions for take off and landing of IFR flight will vary with the location, equipment, and facilities available. Also, high winds, gusty winds, or turbulence may limit helicopter operations.
Minimum cloud height (ceiling) and visibility requirements are established by JAA Regulations. In addition, the helicopter operator may have more conservative rules with which the pilot must comply. Such rules provide safety for the passengers and crew.
Safe operators maintain high standards. Managers or passengers should never pressure the pilot to attempt flight in marginal weather conditions, nor is it wise to "shop" for a pilot who accepts unnecessary risks.

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Do Helicopters Need A Lot of Maintenance?

Although a few parts of the helicopter may be approved to be used until worn to acceptable limits ("on-condition"), the majority must be changed when a time or cycle limit is reached. For example, a part may require inspection each 300 flight hours, overhaul at 2,400 hours and retirement at 4,800 hours. A part that has reached the mandatory retirement time or number of cycles must be destroyed even though it may appear to be in good condition. As in all aircraft, the pilot is required to do a "pre- flight" inspection to insure that the helicopter is ready for flight. A "daily" inspection, usually conducted by an JAA certificated mechanic, may also be required. In addition, the JAA may require additional inspections, such as an annual inspection, a 100-hour inspection, or "continuing" (periodic) inspections according to an approved JAA program.

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How Affordable are Helicopters?

In many instances, helicopters can provide the most cost-effective - and viable ­solution to transportation problems. When speed over short to moderate distances is a priority, or transportation requirements cannot allow for wasted time in highway gridlocks, the helicopter becomes invaluable. Many operations, such as the transport of passengers and cargo over water or into areas not accessible to conventional transportation, cannot be performed as effectively by any other means. In some situations, e.g., transporting critically ill patients, searching for missing persons in rough terrain, or rescuing accident victims from remote areas, the helicopter is not only an affordable solution - it's the only solution.

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What about Helicopter Noise?

Exterior noise, which affects communities, is a continuing concern. The noise from motorcycles, trucks, buses, trash pick-ups, hair dryers, and lawn mowers sometimes exceed the sound levels of modem civil helicopters. People quickly perceive the presence of a helicopter's distinctive sound and relate it to airport jet noise, even though the noise footprints of jet aircraft cover many miles, rather than the hundreds of feet or fractions of a mile covered by helicopters.
Modem civil helicopters are much quieter than the military helicopters that were designed in the 1950s and 1960s. For example, hush kits and other noise reduction techniques are included in modem executive helicopters, which also reduce interior noise to a level approaching that of many automobiles.

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Summary

Helicopters are safe and reliable. The JAA has established stringent maintenance requirements and conducts regular surveillance of all commercial and general aviation operations. As a manager, passenger, or the user of helicopter services, you have many options from which to choose to serve your needs. There are many ways to evaluate the safety of a helicopter operator or pilot. Reputable operators welcome an opportunity to show you their facilities, and they will gladly respond to your questions and concerns. You must clearly explain your transportation needs and ask for their suggestions on how to accomplish each flight safely. Civil helicopter operators and their pilots will always display professional attitudes. They will insist on flying their helicopters safely and neighborly at all times, with your help.

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