12.76.2. Explain the common methods of the mechanical operation of the:

Primary Flight Controls:
Elevator- operated from the cockpit with fore and aft movements of the control wheel or forwards and backwards if using a stick
Ailerons – operated by rotation of the control wheel or sideways if using a stick
Rudder – operatef by pressing the rudder pedals

Trim Tab – operated by using a trim wheel or handle in the cockpit
Flap Systems – operated by a manual lever or an electrical switch

12.72. Propellers

12.72.16. Describe the function and operation of a typical reduction gearbox.

Reduction Gearing
– for most aeroplanes propeller rpm must be limited to about 2,700 rpm because of the speed of sound issue
A reduction gearbox allows a step down to adjust the propeller rpm for the engine rpm

12.72.14. State the principal advantage of a constant-speed versus a fixed-pitch propeller.

Fixed pitch propeller – there is only airspeed at which the propeller will operate at its most efficient angle of attack

Variable speed propeller – the pilot is able to govern the pitch of the propeller blades through a constant speed unit

12.72.12. Explain the basic principle of operation for a constant-speed propeller, and thenormal procedure for changing power settings with the manifold pressure and pitch controls. 

Normally operated on the ground with the pitch control in the FULL FINE position
To increase power
– increase rpm with the pitch control
– then increase MAP (manifold pressure) to desired value with the throttle
–
To decrease power
– First reduce MAP with the throttle
– then reduce rpm with the pitch control

12.72.10. Briefly explain the factors which affect the ability of a fixed-pitch propeller toconvert engine power into useful thrust. 

Air density
– as altitude is gained the amount of thrust produced at any given rpm and airspeed must decline

Propeller tip speed
– when rotational and forward velocity factors are added the tips of the propeller blade can approach the speed of sound. When this occurs compressibility effects on the outer ends of the blades result in a decrease in the thrust produced ; a significant increase in propeller torque creates the npossibility of a noise nuisance

12.72.8. For a fixed-pitch propeller at a constant throttle setting, explain the relationshipbetween airspeed, angle of attack and rpm. 

As airspeed increases the angle of attack of fixed pitch propeller blade at constant RPM will decrease
If the angle of attack is reduced, propeller torque is reduced and engine RPM will increase
With a fixed pitch propeller the angle of attack varies with forward velocity, and with RPM

12.72.6(d) . thrust and propeller torque. 

12.72.6(c) . total reaction, with its components; 

Total reaction force is

Components
– Thrust – component perpendicular to the plane of rotation
– Propeller Torque – the component in the plane of rotation

12.72.6(b) . relative airflow;