SWA B737 - Hydraulics Flashcards
(Hydraulics) How many independent Hydraulic Systems are there?
- Hydraulic System A
- Hydraulic System B
- Standby Hydraulic System
(Hydraulics) How many Hydraulic Pumps do Hydraulic System A and Hydraulic System B have?
- Engine Driven Pump (EDP)
* Electric Motor Driven Pump (EMDP)
(Hydraulics) What is Normal and Max Operating Pressure of the Hydraulic Pumps?
- Normal (3000 PSI)
- Maximum (3500 PSI)
- Minimum During Preflight (2800 PSI)
(Hydraulics) How can the Standby Hydraulic Pump be activated?
- Automatically or
* Manually
(Hydraulics) How do you manually activate the Standby Hydraulic Pump?
By selecting either FLT CONTROL (Guarded) Switch on the Flight Control Panel to STBY RUD
(Hydraulics) When will the Standby Hydraulic Pump automatically turn on?
When all of the following conditions exist:
• Loss of System A or B
• Flaps Extended
• In Flight or Wheel Speed > 60 knots
• FLT CONTROL (Guarded) Switch A or B ON (Standby Pump will also activate if the PCU Force Fight Monitor (FFM) trips)
(Hydraulics) How many Hydraulic Pumps does the Standby Hydraulic System have?
• Electric Pump
(Hydraulics) What does an illuminated LOW QUANTITY light under STANDBY HYD on the Flight Control Panel indicate?
Standby Hydraulic Reservoir Level has dropped below 50% (This light is always armed)
(Hydraulics) How do you know if Hydraulic System A or B need servicing?
An RF (or Refill) will be displayed next to the Hydraulic Quantity (The RF indication is only valid on the Ground with both Engines shut down or after Landing with the Flaps retracted)
(Hydraulics) in Hydraulic System A, where is the Standpipe Protection?
In the Engine Driven Pump (would leave approximately 20% fluid in System A, however if a leak occurs in System A Electric Pump there is no Standpipe Protection and the Hydraulic Fluid Quantity would steadily decrease to Zero and all System Pressure would be lost)
(Hydraulics) In System B, where is the Standpipe Protection?
Both the Engine Driven and Electric Pump (If a leak develops in any component of System B the Quantity would indicate Zero and System B Pressure would be lost, however there would still be fluid in the reservoir - this is to provide sufficient hydraulic fluid for Power Transfer Unit (PTU) operation)
(Hydraulics) How is the Standby Hydraulic Reservoir Pressurized?
It is not directly pressurized, however since Hydraulic System B is pressurized, this exerts power on the Standby Hydraulic Fluid
(Hydraulics) Do the System A and B Engine Driven Pump switches turn the Hydraulic Pumps ON and OFF?
No - when the Engines are running the Engine Driven Pumps are also ON. The switch operates a Blocking Valve which will block the fluid if the switch is in the OFF position.
(Hydraulics) What does an illuminated LOW PRESSURE over the Hydraulic Pump Switches on the Hydraulic Panel indicate?
The Associated Output Pressure is Low (When the associated Engine Fire Warning Switch is pulled, the Hydraulic SOV will close, however you won’t get those lights because the LOW PRESSURE lights are deactivated)
(Hydraulics) How is the Engine Driven Pump cooled and lubricated?
By fluid flowing through the pump (even with the Blocking Valve Energized, since it is downstream of the Pump it is still cooled and lubricated by moving Hydraulic Fluid through the Pump then back to the Reservoir)
(Hydraulics) Why is the Hydraulic System A Electric Pump labeled ELEC 2 and the System B Electric Pump labeled ELEC 1?
To indicate their Power Source
• System A ELEC 2 means it is powered by AC Transfer Bus 2
• System B ELEC 1 means it is powered by AC Transfer Bus 1
(Hydraulics) Where is the Heat Exchanger to cool down the Hydraulic Fluid located?
- Heat Exchanger for Hydraulic System A is in Main Fuel Tank 1
- Heat Exchanger for Hydraulic System B is in Main Fuel Tank 2 (a minimum of 1675 lbs of fuel in each Main Fuel Tank is required to provide proper cooling)
(Hydraulics) What does an illuminated OVERHEAT light over the ELEC 1/2 switch on the Hydraulic Panel indicate?
That the Hydraulic Fluid OR the Electric Motor Pump has Overheated
(Hydraulics) What does an illuminated LOW PRESSURE light under STANDBY HYD on the Flight Control Panel indicate?
The Output Pressure if the Standby Hydraulic Pump is Low (this light is only armed whenever the Standby System is activated)
(Hydraulics) On the Flight Control Panel with the FLT CONTROL (Guarded) Switches A ON and B ON what does this do?
Allows Hydraulic System A and B to power the Primary Flight Controls
(Hydraulics) What does an illuminated LOW PRESSURE light under the FLT CONTROL A and B (Guarded) Switch on the Flight Control Panel indicate?
Low Pressure in the associated Hydraulic System to the Ailerons, Elevator, and Rudder
(Hydraulics) What does moving the FLT CONTROL A or B (Guarded) Switch to OFF do?
Closes the Flight Control SOV - isolating the Ailerons, Elevators, and Rudder from the associated Hydraulic System
(Hydraulics) What does moving the FLT CONTROL A or B (Guarded) Switch to STBY RUD do?
Activates the Standby Hydraulic System Pump and opens the Standby Rudder SOV to pressurize the Standby Rudder Control Unit
(Hydraulics) When will Hydraulic System B Engine Driven Pump supply the Hydraulic Fluid to the Landing Gear Transfer Unit (LGTU) to raise the Landing Gear?
All of the following conditions have to be met: • Aircraft in Flight • Number One Engine Fails • Landing Gear Lever is UP • Either Main Gear is NOT Up and Locked
(Hydraulics) What does the Power Transfer Unit (PTU) operate?
- Leading Edge Flaps
- Slats
- Auto Slats
(Hydraulics) How does the Power Transfer Unit (PTU) work?
Uses Fluid Pressure from System A to drive a pump which in turn pressurizes System B when it’s Engine Driven Pump is lost
(Hydraulics) What conditions must exist for the Power Transfer Unit (PTU) to automatically operate?
All of the following conditions must be met:
• System B Engine Driven Pump Fails
• Aircraft in Flight
• Flaps are less than 15, but not Up
