Prop System Flashcards
RPM (in flight) is controlled by the
Blade angle?
Fuel topping governor
28 degree switch
Pitch lock reset
32 degree switch
Oil cooler inducer
Prop flight idle stop
Prop sync
36 degree switch
Low rpm interlock
48 degree switch
Landing gear warning system
60 degree switch
Autofeather system
Landing gear warning system
Takeoff position degree?
90 degrees
34 to 90 degrees
Flight range
Power lever position Ground start
What is the coordinator position and blade angle?
15 degrees
0 degrees
Power lever position Ground Idle
What is the coordinator position and blade angle?
9 degrees
-6 degrees
Power lever position Max Reverse
What is the coordinator position and blade angle?
0 degrees
-13 degrees
Beta range blade angle controlled by…
RPM controlled by…
Blade angle range in beta?
Power lever position
Fuel controlled unit
-13 to 11 degrees
When does electronic governing work?
- SYNC SERVO switches to NORMAL with a master prop selected
- Power levers above 32 degrees coordinator
Autofeather actuation
- electrically armed
- power lever above 60 degrees coordinator
- prop producing less than 500 lbs thrust
- no other feather button in feather position
Autofeather priority
4,1,3,2
NTS lever position for actuation
Greater than 24 degrees
Engine safety coupling range
-500 to -1700SHP
Beta follow up minimum blade angle range
11 degrees to 68 degrees coord then to 22.5 to 88.
Takeoff: 22.5 to 90
Low pitch stop
Mechanicle limits blade angle to 13 degrees min.
Pitchlock over speed limit
Blade angle range
103.5 percent
17 and 57 degrees blade angle
Speed biased motor
2.5% sensed
Plus 6 minus 4% rpm
What blade angle does the backup valve close
Less than 24 degrees
Low pitch stops coordinator position
Below 28 degrees
E handle functions
- S: Shuts off fuel at fuel control unit (E and M)
- A: Actuates feather system (E)
- M: Moves propeller feather valve to feather position (M)
- C: Closest fuel tank emergency shut off valve (M)
- C: Close is bleed air shut off valve (E)
- C: Close his generator cooling air shut off valve (M)
- D: Dumps engine driven compressor two and three only and closes firewall shut off valve (E)
- C: Closes oil tank shut off valve (E)
Prop Malfunction definition
Prop pump light
Visible Fluid leak
Offspeed condition (audible)
Prop off speed condition characterized by
Indicated rpm is greater than 1 percent above or below the mechanical / electrical governing rpm or any sustained rpm occscilstion occurs (detected audibly)
Two ways automatic pitch lock engagement can occur
1: Loss of control oil pressure
2: Rpm exceeds approximately 103.5%
Feather button
In: (2 things)
Out: (2 things)
In: Activates the feather valve solenoid and pump energized
Out: Aux pump runs
Arms the 45 degree air start protections circuitry
Pilot valve senses under speed and ports fluid to decreased side and turning on fuel and ignition switches initiates start sequence and NTS likits negajtve torque by controlling BA until Normal RPM
Sync box importance
You can’t reinforce pitch lock without the sync box, even if sync inop
Four safety features to drive the blade to high angle / low pitch (feather)
NTS
Feather signal for 45degree airstart protection
Feather signal from fx button
Feather signal from e handle
(All require hyds)
Four safety features for undersidred extreme reduction in blade angle
Pitch lock
Pitchlock reset
Beta follow up
Mechanical low pitch stop
What does the feather button do in the armed position?
Electrically energized fx valve solenoid
Electrically energized the AUX pump
Electrically shuts off fuel at the fuel control
What does the PCO button do?
Denergizes the feather cut out relay causing
- Energizes the AUX PAump
- Energizes and verifies ops of the fx valve solenoid
- pressurizes the increased pitch side of the control piston to replenish any voids or air pockets
(Releasing PCO terminates AUX pump operation and Denergize is the fx valve solenoid resulting in feather valve returning to the neutral position)
Indications of a pitch locked prop
RPM extremely sensative to changes in TAS
Increase in RGB oil px if rpm above 100%
SHP indicates 0 or wandering
FF is 600lbs/hr
Indications of a coupled prop with no NTS action (the bad)
Decreased RPM
Power section oil px normal
SHP steady in negative range and responsive to changes in TAS
Indications of a prop decoupled with no NTS (the ugly)
RPM extremely sensative to changes in TAS
SHP near 0 or wandering not responsive to changes in TAS
power section oil px decreasing to 0 (May stabilize above 0 depending on windmilling energy)
Indications of pitchlock without over speed
Regarding power lever produces a decrease in RPM but moving it forward only goes to 100% rpm
If decouple is due to fuel cutoff engine indications
SHP indicates near 0 and wander RPM will initially surge but stabilize at 100% TIT decrease toward ambient FF 0 Power section oil px at or near 0
If decouple is due to decoupler failure engine indications
SHP indicates near 0 and wander
RPM will stabilize at 100%
TIT 550
FF 600lbs/hr
Betta follow up blade angle
Mechanical low pitch stop?
Minimum of 22.5 degrees blade angle at 90 degrees coordinator
13 degrees blade angle
What is in the barrel?
The dome?
Control assembly
Pump Housing
Valve Housing
Pitch lock regulator and fluid
Pitch control piston and cam and gear train (converts push pull to rotary motion)
Pump housing and valve housing
Hydraulics & sumps
Prop governor, pitot valve, speeder spring, flyweight, servo spool (to direct prop fluid to and from dome), main, stby & back up regulator valves, alpha & beta shafts
Blade angle range
-13 (full reverse) to 86 degrees (full feather
Two types of sumps
Atmospheric
- main pump: driven by prop
- aux: driven by electrical feather motor
(To maintain prop fluid and px in the atmospheric sump) regulated through a sump relief valve mounted on both pumps
Pressurized:
- main: driven by prop (prop pump 1)
- standby: (prop pump 2)
- aux pump: used for feather, unfeather and static ground ops
Prop pump 1 output in quarts per minute
Prop pump 2?
20 quarts
40 quarts (stays in standby status though)
Main and stby regulator valves keep what PSI in the system?
Back up valve purpose?
150 PSI
Prevents retraction of low pitch stops in flight and proves prop fluid to break the feather latches when unfeathering (closes when power levers greater than 28 degrees coordinator and below 24 degrees BA (low power low speed))
Where does the alpha shaft recieve input from?
Beta shaft?
The coordinator and E handle
The number one blade of the prop
What does the speed set cam do?
Sets 100% rpm in the flight range by compressing the speeder spring below flight idle
What does the Beta set Cam do?
Sets blade angle in the beta range and provides for beta follow up in flight range with beta follow up set cam
What does the feather and disarm cam do?
Positions feather valve to feather when E handle is pulled. Repositions NTS linkage to prevent feather valve actuation below 24 degrees coordinator
What does the Alpha back up cam do?
Opens the backup valve below 28 degrees coordinator to provide decrease pitch px to retract low pitch stops
What does the Alpha pitch lock reset cam do?
Energizes the pitch lock reset solenoid below 28 degrees coordinator (if BA is below 10 degrees)
What is the Solenoid operated flight idle stop?
Blocks power levers from going over the ramp in flight (especially if linkage were to be disconnected ) Removed when scissor switch senses weight on wheels and power lever below 32 degrees.
Can be overcome by 12 lbs of force if it fails to retract
What does the Beta back up valve cam do?
Opens backup valve above 24 degrees BA and closes below 24 degrees to prevent retracting low pitch stops
What does the Beta air start can do?
Energizes the feather valve solenoid at 45 degrees BA when fx button held out
What does the feather cutout switch cam do?
The reset cam?
Prevents pressure surges from terminating feather circuit until 71-76 BA
D’energia ed pitch lock reset solenoid when below 10 degrees BA
Speed bias servos range
96-106%
