Aerodynamics, Assembly & Rigging

Forces Dyne

The study of objects in motion through the air and the _______ that motion come from the Greek combination of "aero" and _________

inches of mercury barometer

Atmospheric pressure is measured in ________ with a _______

Drops Decreases Drops

As an aircraft descends atmospheric pressure _________ the amount of oxygen in the air ________ and temperature _________

Inversely Direct Proportion

Density varies ___________ with temperature and ________ with pressure.

Motion Inertia

A body at rest does not move unless a force is applied to it is Newton's _______ law and is known as the law of _______

Increase

According to Bernoulli's principle, fluid flowing through a constriction experiences an ________ in speed

Upper surface

Velocity increases and pressure decreases on the _________ of the wing.

Angle of Attack

A pilot can increase the lift of an aircraft by in creasing the ________

Longitudinal

The acute angle the wing chord makes with the __________ axis is called the angle of incidence.

Fluid Pressure

The boundary layer is the layer of ________ closest to the surface and its behavior is controlled in order to minimize ______________ drag and skin friction drag

High Low Outward from fuselage A vortex

Fluids always move from ________ to ________ pressure. This principle explains the span wise movement of air flow from the bottom of the wing ____________ and upward around the wing creating over the wingtip called ___________

Static

An object that tends to return to equilibrium is said to have positive _______ stability

Ailerons Elevator Rudder

__________ control the lateral movements of the aircraft, the ________ controls the longitudinal movements, and the ___________ controls the directional movements.

Free-Spinning Upward

An autogyro is an aircraft with a horizontal rotor that is ________ and turns due to the passage of air _________ through the rotor.

Down

The blade with the decreased angle of attack tends to flap ________

Left Pitch Angle

The collective pitch control is operated with the _______ hand and is used to make changes to _________ the main rotor blades.

Dissymmetry

There is a _______ of lift between the advancing and retreating blade.

Clutch

Autorotation is possible through a freewheeling unit, a special _________ mechanism, which automatically disengages the engine in the event of its failure.

Right Left

Helicopters with tandem rotors use the pedals to tilt the main rotors. When the _______ pedal is pushed forward the aft rotor moves to the ________

"Go" "No-Go"

Swaging tools generally have a _____________ dimensions in an attempt to avoid defective or inferior swages.

Fairlead 3-degrees

Cables that travel completely through bulkheads require the use of a ____________ and should not be deflected more than _______ from a straight line

Turnbuckle Left Hand

A groove or knurl around the end of the barrel of a _________ can be used to identify the _______ threads

Position/angle Wingtips

Structural alignment id the __________ of the main structural component related to the longitudinal datum line parallel to the aircraft centerline and the lateral datum line parallel to the line joining the _______

Dihedral Incidence

Hard landings and abnormal flight experiences prompt a check of the wing _______ and angle of ________

Double-Twist Single Wire

The most common method of safety wiring is the ________ however, a ________ method can be used for smaller screws.

True

Air is considered a fluid

True

Atmospheric pressure changes with altitude

False

Aircraft can fly faster at lower altitudes because there is more pulling force from the engine cutting through the air.

TRUE

Air is considered a fluid.

TRUE

Atmospheric pressure changes with altitude.

FALSE

Aircraft can fly faster at lower altitudes because there is more pulling force from the engine cutting through the air

FALSE

Density varies directly with humidity.

TRUE

Airflow over an airfoil can be explained using Bernoulli's principle and this pressure differential is called lift.

TRUE

One wing can have numerous airfoil sections each with unique properties.

False

The efficiency of a wing is measured in terms of wing camber and AOA.

True

An aircraft has four forces acting upon it at all times: gravity, lift, thrust and weight

True

Induced drag increases as AOA increase.

False

Center of pressure has the greatest affect on the stability of an aircraft

False

The vertical stabilizer is the primary surface that controls adirectional stability on the horizonal axis.

True

Trim tabs enable the pilot to correct any unbalanced condition that may exist during flight without touching the flight controls.

False

Canards are often used in swept wing aircraft to prevent spanwise air movements at high angles of attack

True

Stick shakers were installed in hydromechanical flight control systems which provide an artificial stall warning.

False

Stick shakers were installed in hydromechanical flight control systems which provide an artificial stall warning.

False

At high forward speed a situation called retreating blade stall can occur because of the high AOA and slow relative wind speed.

True

Control surfaces must be rebalanced whenever there is weight added to a control surface.

False

The balance beam rebalancing method requires a specialized manufacturer made tool.

True

Lead and steel are the most common materials used to balance control surfaces

True

The Type certification Data Sheet is issued by the manufacturer and includes information such as airspeed limitations, weight limits, and fuel type.

True

A 7x19 cable is very rigid and used for engine controls and trim tab controls.

False

Soldering cable ends is a common technique used to prevent fraying.

True

Cables are checked for corrosion by bending them.

True

A double-wrap safety wire method is preferred when securing a turnbuckle.

True

Rudder align ment is done by removing the controls surface from its hinges and passing a plumb bob though the hinge attachment holes.

False

Cotter pins, unlike safety wire, can be re-used.

Why is air considered a fluid?

It fits the definition of a substance thet has the ability to Flow or assume th shape of the container which it is enclosed.

What is the atmospheric pressure and how is it measured?

Atmospheric pressure is defines as the force exerted again the earth's surface by weight of the air above that surface. Atmosphere pressure is measured with an instrument called a barometer, composed of mecury in a tube that records atmospheric pressure in inches of mercury.

What is the relationship between density, pressure, and temperature?

-Density varies in direct proportion with the pressure

-Density varies inversely with the temperature

What is the difference between absolute humidity and relative humidity?

-Absolute humidity is the weight of water vapor in a unit volume of air

-Relative humidity is the ratio in percent of the moisture actually in the air to the moisture it would hold if it were saturated at the same temperature and pressure.

What is Newton's third law and what does it state?

Law of action and reaction. This law states that for every action (force) there is an equal and opposite reaction (force).

Describe how bernoulli's principle related to a wing.

Bernoulli's principle relates to a wing by describing the difference in airflow between the air flowing over the top fo the wing and the air flowing beneath the wing which causes lift.

Describe what happens to the resultant force as the AOA increases.

The resultant force moves the same as the center of pressure. When AOA increases, the CP moves forward which means the resultant force moves forward as well.

What does control and controllability mean for a pilot and the aircraft?

For a pilot Control and Controllability means being able to use controls such as ailerons, rudders, vertical stabilizer etc..... to help control and manuever during flight.

Explain the aerodynamic effect that occurs at and above the speed of sound.

Near and beyond the speed of sound typically around 760 mph sharp disturbances generate a shockwave that affects both the lift and drag of an aircraft and flow conditions downstream of the shockwave, The shockwave forms a cone of pressurized air molecules which move outward and rearward in all directions and extend to the ground.

Explain what fully articulated means in relation to a helicopter rotor system.

Fully articulated rotor blade systems provide hinges that allow the rotors to move fore and aft as well as up and down.

How does Newton's third law relate to helicopters?

As the engine turns the main rotor system in a counterclockwise direction, the helicopter fuselage tends to turn clockwise.

Explain what a correlator is and what it does.

A correlator is a mechanical connection between the collective lever and the engine throttle. When the collective lever is raised, power is automatically increased and when lowered power is decreased.

What are the most common causes of high frequency vibrations?

When tail rotor gears, tail drive shaft, tail rotor engines, fan or shaft assembly vibrates or rotates at an equal or greater speed then the tail rotor.

Why is no clutch necessary on a helicopter engine with a free turbine?

Due to the gas producer turbine being essentially disconnected from eh power turbine.

Describe the use of pulled and pulley guards

A pulley is used to guide a cable and also the change the direction of cable movement. Fully guards are close firing to prevent jamming or to prevent the cables from slipping off when they slacken due to temporary vibrations.

Control cable rigging generally consists of what three steps?

1. Positioning the flight control system in neutral and tempering locking it there with rig pins or blocks.

2. Adjusting system cable tension and maintaining rudder, elevator and ailerons in the neutral position.

3. Adjusting the controls stops to the aircraft manufacturer's specifications.

What is the purpose of a turnbuckle?

To make minor adjustments in cable length and for adjusting cable tension.

Where are the cable drums typically found and what do they do?

Found in trim tab systems. As the trim tab control wheel is moved clockwise or counter clockwise, the cable drum winds or unwinds to actuate the trim table cables.

What are the types of inspection programs helicopter operates used in accordance with 14 CFR part 91?

1. Annual Inspection

2. 100-Hour inspection, when being used for compensation or hire

3. A progressive inspection, when authorized by the FAA.

4. An inspection program listed under 14 CFR part 91 section 91.409(f), when selected by the owner/operator and the selection is recorded in the aircraft maintenance record 14 CFR part 91, section 91.409 (e)

What happens to the pressure of a fluid in a container when it is heated?

Pressure Increases

At sea level, what is the average atmospheric pressure in psi, Hg, and millibars respectively?

14.7 psi, 29.2 "Hg, 1013.25mb

A wing with a high fineness ratio has which of the following characteristics?

Thin wing, large amount of skin friction.

When the AOA increases to maximum lift, what has been reached?

Critical Angle and Burble Point

Force acts in what direction, in relation to the relative wind?

Perpendicular

Exposed aircraft components create resist known as

Parasite drag

____________ is quality of the response of an aircraft to the pilot's commands during maneuvers.

Controllability

Which axis extends from nose to tail?

Longitudinal axis

What type of stability can be artificially increased with a yaw damper?

Directional

Which of the following type of aircraft structures reduce fuel consumption and increases range?

Winglets

Compressible aerodynamics deals with speeds at

Mach 1 and above

Supersonic flight refers to flight between

Mach 1 and Mach 3

What type of rotor is found on aircraft with dual rotor blades?

Semi rigid

Drift in the direction of the tail rotor during hover is called

Translational tendancy

Effective translational lift if experienced at what air speed?

Between 16-24 knots

A helicopter with counterclockwise rotating main rotor would experience which of the following conditions if dissymmetry of lift were allowed to exist with no corrective action?

Roll to the left

How does a pilot compensate for blowback?

Move the cyclic forward

What component transmits the control inputs from the collective and cyclic to the main rotor blades?

Swash Plate

Where is the throttle control located in a helicopter?

On the collective

What is the primary purpose of the helicopter main rotor transmission?

Decrease engine output RPM to optimum rotor RPM

During static balancing, an upward movement of the trailing edge of a control surface on a balance stand indicates:

An overbalance designated with a (+) sign

Which rebalancing method can be performed without removing the control surface from the aircraft?

Calculation method.

Where should rigging and alignment checks be performed?

In an enclosed hangar

________ may be used to force the primary nut thread against the bolt or screw thread.

Pal nut

ELT tests should be conducted

During the first 5 minutes of any hour

High Speed Aerodynamics

Often called compressible dynamics, is a study of aeronautics

True

Better flight operations are gained by nose-heavy static overbalance