Hydraulics Flashcards
When will the demand pumps operate if the hydraulic demand pump selector is in the AUTO position?
- Demand pumps operate when related engine pump output pressure is low, or when respective fuel control switch is in CUTOFF
- Demand pumps 1 & 4 also operate when flaps are in transit on ground , or flaps extended past 1 in flight
What does the hydraulic system (SYS FAULT) fault light indicate?
- Low hydraulic system pressure
- Low hydraulic reservoir quantity
- Excessive hydraulic fluid temperature
What does a hydraulic demand pump low PRESS light indicate?
- Demand pump selector positioned to OFF or AUX
* Demand pump commanded to operate and output pressure is low
What does a hydraulic reservoir quantity indication of .80 mean, as displayed on the Secondary EICAS display?
• 80% of normal service level
What does a magenta “RF” displayed next to a hydraulic quantity indicator on the Secondary EICAS mean?
• The reservoir requires refill
When is the engine driven hydraulic pump pressurized?
- The engine is running
* The engine pump switch is ON
Which demand pumps are air driven, and which ones are electric motor driven?
No wing fence.
- Systems 1 and 4 are air driven pumps, through the bleed air manifold.
- Systems 2 and 3 are electric driven pumps.
What is the purpose of the auxiliary pump?
• Used for ground handling operations
Why are the hydraulic reservoirs pressurized by the bleed air system?
- To prevent pump cavitation
* To ensure positive flow during high demand conditions
How does pulling a fire switch affect the hydraulic system?
- Respective hydraulic fluid shutoff valve closes.
- The EDP depressurizes.
- The respective demand pump operates.
What will cause a Hydraulic System Fault to illuminate? (Two lows and a high)
Low hydraulic system pressure
Low hydraulic reservoir quantity
Excessive hydraulic fluid temperature
What will cause the #1 and #4 demand pumps to operate when in. the Auto position?
Engine Demand Pump output low or Fuel Control switch placed to CUTOFF.
Also Trailing Edge Flaps in transit past 1 on the ground, or Trailing Edge Flaps extended past 1 inflight.
What demand pumps are electric, and which are pneumatic?
no wing fence
Pumps #1 and #4 are pneumatic and #2 and #3 are electric.
What do I monitor when placing the #4 demand pump selector to AUX?
Verify SYS FAULT light extinguished
PRESS light remains illuminated
BRAKE SOURCE LIGHT extinguished
BRAKE ACCUMULATOR PRESSURE indicator in the
GREEN band.
With the loss of hydraulic system 4 how do I lower the landing gear and flaps?
The Landing gear will have to be lowered using the Alternate Gear Extension switch.
The flaps will revert to Secondary mode and extend more slowly.