AIRCRAFT PROPELLER (MIDTERM) 2

Question 1

Fixed-Pitch Propellers
Ground Adjustable Propellers
Variable Pitch Propellers
● Controllable Pitch Propellers
● Constant Speed Propellers

Question 2

is an engine rpm sensing device with
a high pressure oil pump.

Answer 2

Propeller Governor

Question 3

In a constant-speed propeller
system, the governor responds to a change in engine rpm
by directing oil under pressure to the propeller hydraulic
cylinder or by releasing oil from the hydraulic cylinder,
depending on system design.

Answer 3

Propeller Governor

Question 4

The change in oil volume in
the hydraulic cylinder changes the blade angle and
maintains the engine rpm

Answer 4

Propeller Governor

Question 5

FACTORS USED TO CHANGE ANGLE IN A
CONSTANT SPEED PROPELLER

Answer 5

• Centrifugal Twisting Moment
• Propeller Governor Oil
• Propeller Blade Counterweight
• Pneumatic pressure against the propeller
  piston
• Springs
• Aerodynamic twisting moment

Question 6

a component of the
centrifugal force acting on a rotating blade that tends at all times to
move the blade into low pitch

Answer 6

Centrifugal twisting moment

Question 7

on the propeller piston side of the
governor moves the blades to low pitch. This balances against the
propeller blade counterweights. The latter moves the blades
toward high pitch.

Answer 7

Propeller Governor Oil

Question 8

always move the blades
toward high pitch

Answer 8

Propeller blade counterweights

Question 9

pushes toward high pitch.

Answer 9

Pneumatic pressure against the propeller
piston

Question 10

push in the direction of high pitch and
feather.

Answer 10

Springs

Question 11

moves
the blades toward high pitch.

Answer 11

Aerodynamic twisting moment

Question 12

The most powerful force is the _______ acting on the propeller
piston.

Answer 12

governor
oil Pressure

Question 13

The engine driven single
acting propeller governor
(constant-speed control)
receives oil from the
engine’s lubrication system
and boosts that pressure to
that required to operate the
pitch changing mechanism

Answer 13

Governor mechanism

Question 14

Key components

Answer 14

• Flyweights
• Speeder spring
• Pilot valve
• Governor Pump

Question 15

These sense changes in engine speed.

Answer 15

Flyweights

Question 16

Sets the desired RPM by balancing the
flyweight force.

Answer 16

Speeder spring

Question 17

Controls the flow of oil to and from the propeller
hub.

Answer 17

Pilot valve

Question 18

Increases oil pressure for blade pitch changes

Answer 18

Governor Pump

Question 19

When the engine is
operating at the rpm set
by the pilot using the
cockpit control, the
governor is operating

Answer 19

On speed

Question 20

When the engine is
operating above the rpm
set by the pilot using the
cockpit control or the
redline adjustment of the
governor, the governor is
operating in an over
speed condition

Answer 20

Overspeed

Question 21

When the engine is
operating below the rpm set
by the pilot using the cockpit
control, the governor is
operating in an under speed
condition

Answer 21

Underspeed

Question 22

Hartzell propellers can be classified by aluminum
hub (compact) and steel hub. Hartzell compact
aluminum propellers represent new concepts in
basic design. They combine low weight and
simplicity in design and rugged construction.

Question 23

In order to control the pitch of the blades, a hydraulic piston cylinder
element is mounted on the front of the hub spider.
The piston is attached to the blade clamps by means of a sliding rod
and fork system for non-feathering models and a link system for the
feathering models.
The piston is actuated in the forward direction by means of oil
pressure supplied by a governor, which overcomes the opposing force
created by the blade counterweights

Question 24

Feathering occurs because the summation
of internal propeller forces causes the oil to
drain out of the propeller until the feather
stop position is reached

Question 25

● Feathering is accomplished by releasing the governor oil pressure
from the piston assembly, allowing the counterweights and
feathering spring to feather the blades.
● This is done by pulling the condition lever (pitch control) back to
the limit of its travel, which opens up a port in the governor
allowing the oil from the propeller dome to drain back into the
engine.
● As the oil drains from the piston assembly, the actions of the blade
counterweights and feathering spring work to increase propeller
pitch.