DB's SY 737 Hydraulics Flashcards
Hydraulic Pump LOW PRESSURE lights - Illuminated (Amber)
Output pressure is low
Note: when an engine fire handle is pulled, the low pressure light is deactivated.
Electric Hydraulic Pump OVERHEAT lights - Illuminated
Hydraulic fluid used to cool and lubricate the corresponding electric motor driven pump has overheated or the pump itself has failed.
ELECTRIC HYDRAULIC PUMPS Switches
- ON
- OFF
- Provides power to associated electric motor-driven pump
2. Electric power removed from pump
ENGINE HYDRAULIC PUMPS Switches
- ON
- OFF
- De-energized blocking valve in pump to allow pump pressure to enter the system (normally remains ON to prolong solenoid life)
- Energizes blocking valve to block pump output.
- At what hydraulic quantity will the RF light illuminate?
2. When is the RF light valid?
- Hydraulic quantity below 76%
2. Valid only when airplane is on the ground with both engines shutdown or after landing with flaps up during taxi in.
What pressurizes the system A and B reservoirs?
Bleed air
What pressurizes the standby hydraulic system reservoir?
The system B reservoir
What components are powered by SYS A?
Airlerons Rudder Elevator and elevator feel Autopilot A Landing gear Ground spoilers flight spoilers (2) Alternate brakes Nose wheel steering Thrust reverser #1 PTU
What components are powered by SYS B?
Ailerons Rudder Elevator and elevator feel Autopilot B Leading edge flaps and slats TE flaps flight spoilers (2) Yaw damper Brakes Alternate NWS Autoslats Thrust reverser #2 LGTU
What components are powered by the Standby Hydraulic system?
Thrust reverser
Rudder (STBY)
LE Flaps/Slats
Yaw damper (STBY)
What is the purpose of the LGTU?
Supply the volume of hydraulic fluid needed to raise the landing gear at the normal rate when the system A engine-driven pump is lost.
When will the SYS B engine-driven pump supply the needed hydraulic to operate the LGTU?
When all of the following conditions exist:
- In flight
- No. 1 engine RPM drops below a limit value
- LANDING GEAR lever is UP
- Either main gear is not up and locked
What is the purpose of the PTU?
To supply the additional volume of hydraulic fluid needed to operate the autoslats and leading edge flaps and slats at the normal rate when SYS B engine-driven hydraulic pump is lost.
When will the PTU use SYS A pressure to power a hydraulic motor-driven pump, which pressurizes SYS B fluid?
When all of the following conditions exist:
- SYS B engine-driven pump pressure drops below limits
- In flight
- Flaps are less than 15 but not UP (only not UP for 820SY/821SY)
What powers
- SYS A engine-driven pump
- SYS B engine-driven pump
- Either electric hydraulic pump
- No. 1 engine
- No. 2 engine
- The opposite side AC transfer bus
How are the hydraulic fluid for SYS A and B cooled?
A heat exchanger located in the respective main fuel tanks
Note: Min fuel quantity is 1675 per tank
What fluid quantity would be shown a leak develops in
- SYS A engine-driven pump or related lines
- SYS B engine-driven pump or related lines
- Either electric pumps or related lines
- 20% (due to standpipe in SYS A reservoir)
- 0% (However there is a standpipe in B reservoir that retains enough fluid to power the PTU)
- 0%
What fluid quantity would be shown if SYS B leak develops in
- SYS B engine-driven pump
- Either electric pumps or related lines
- 0%
- 0%
(However there is a standpipe in B reservoir that retains enough fluid to power the PTU.
If SYS B hydraulic fluid drops to 0%, can the PTU still operate and why?
Yes, SYS B reservoir has one standpipe which supplies fluid to engine and electric pumps. With fluid level at the top of the standpipe, fluid remaining in SYS B reservoir is sufficient for PTU operation.
How can we manually operate the STBY hydraulic pump?
- Either FLT CONTROL switch to STBY RUD
2. ALTERNATE FLAPS master switch to ARM
When does the STBY hydraulic pump automatically operate?
- Loss of SYS A or B
- Flaps extended
- In flight, or wheel speed greater than 60kts
- FLT CONTROL switch A or B hydraulic SYS ON
- The main PCU Force Fight Monitor trips
What chain of events happen when the STBY hydraulic system operates automatically?
- STBY elec pump is activated
- STBY RUD SOV opens
- Allows the STBY SYS to power the rudder and thrust reversers
- Illuminates the STBY RUD ON, master caution and Flight Controls lights
What will the quantity of the STBY reservoir be if:
- There is a leak in the STBY SYS? Also, what about SYS B quantity?
- Leak in SYS A or B?
- LOW QUANTITY light on STBY Hydraulic Panel illuminates
- STBY = 0% SYS, B = 72%
- STBY reservoir is unaffected by a leak in SYS A or B
- 50%
During what operations is it normal to see variations in hydraulic quantity indications?
- When the system becomes pressurized after engine start
- When raising or lowering the gear or LE flaps
- When cold soaking occurs during long cruise periods
- When would Hydraulic foaming occur?
2. What indications would we see?
- When the hydraulic system is not properly pressurized
2. Pressure fluctuations, blinking of related LOW PRESSURE lights and/or MASTER CAUTION/HYD lights
What is the minimum fuel quantity in the related main fuel tanks for ground operation of electric motor-driven hydraulic pumps?
1675 lbs
