5 DHC-6 Propellers
Home > Preview
The flashcards below were created by user
on FreezingBlue Flashcards.
Manufacturers name and prop Diameter
8 ft 6 inches
Degrees of pitch?
Full Course & Full Fine?
When does Beta warning and backup come in?
+870 Full Course
+17o Full Fine
Beta Backup at 9o
Degrees of Pitch
Zero Thrust & Max Reverse
At what point in reverse does Ng increase?
Zero thrust 00
Max Reverse -15o
Ng increases at -20
What pressure is engine oil boosted to by the gear pump at the base of the prop governor?
How does prop feather?
When rotating but counterweights at the blade roots and centrifugal force.
When stationary by large spring pressure on the propellor dome
For a fixed power setting and given RPM , describe the relationship between blade angle and RPM
RPM is a function of blade angle, and blade angle is a function of true airspeed.
Describe Beta Range
Prop is in beta range whenever the prop RPM is less than selected with prop lever.
What controls the blade angle in beta range?
Blade angle controlled by the Beta Valve
which is in turn controlled by the power lever
- If the CSU cannot achieve the speed selected, the Beta Reverse Valve (BRV) will prevent the blade angle from decreasing below 11o min for all ops in forward power range.
What blade angles do the BRV functions come in?
BRV begins to restrict oil supply as blade angle decreases below +21o
Limits blade angle to +17 in flight and +11 at idle
Describe the function of the Beta backup valve
Prevents the prop from going below +9o when the prop levers are forward of idle.
Cycles between 9 and 11 degrees and activates only in abnormal circumstances and malfunctions.
Deactivated by microswitch in power lever quadrant for reverse ops
What indicates that the Beta Backup has malfunctioned and activated above +9o?
Steady blue Beta light
Differences between BRV and Beta Backup?
BRV Mechanically operated - Beta Backup Electrical
BRV modulating valve with infinite range of positions - Beta backup solenoid, fully open or closed
BRV operates every taxi, approach, landing - Backup only during abnormalities
What indicates the BRV has malfunctioned?
Cycling Beta light
Slight Yaw as the prop hunts between 9 and 11 degrees (Beta backup valve is working properly!) -Steady light land ASAP-Flashing light saves lives
How many governors protect prop overspeed?
- Primary governor (Np)
- Overspeed governor
- Gas Gen governor (Ng)
- Fuel Topping governor (NF)
What will the overspeed governor limit the RPM to?
What will it govern to during a test?
101.5% Np during a failure
70% Np during a test
What is the Ng governor?
Integral part of FCU, it's sole function is to provide gas gen speed scheduling.
It does not control the propellor
What is the NF Governor.
Protects against turbine overspeed by limiting fuel flow
At what percentage discrepancy between RPM and lever position will the NF governor it begin to operate.
Will cause FCU to limit fuel if prop RPM gets 6% higher than what is selected.
With props full forward, when will the NF Governor begin to govern?
When power levers are moved into reverse it resets to 5% below the 96% set by the props at MAX
Auto feather requires how many seconds of torque loss before initiating auto-feather.
Under what conditions will auto-feather be ARMED?
It is turned on
Both power levers are above 86-88% Ng
Both engines are developing more than 20-25psi
Amber ARMED light will come on
Auto Feather will only feather under what conditions?
It is turned on
Both power levers are below 86-88%
Torque decreases to below 11psi on one engine for more than 2 secs
What compensations must be made when not using autofeather
add 4kts to Vr and V1 & V2
Power/ Prop settings for
Take-off 50/45psi - Max RPM (96%)
Climb 45psi 85% RPM to 5,000ft
Cruise 40psi 75% RPM
Home > Flashcards > Print Preview