Hydraulic Flashcards by Jesus Jimenez

What does the Demand Pump Selector do when set to ON?

ON - demand pump operates

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What happens when the ENGINE Hydraulic Pump Switch is set to ON?

ON - engine hydraulic pump pressurizes system when engine rotates.

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What conditions cause the Hydraulic System (SYS) Light to illuminate?

Illuminated (amber) - low hydraulic system pressure, low hydraulic reservoir quantity, excessive hydraulic fluid temperature

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What does the Demand Pump PRESS Light indicate when illuminated?

Illuminated (amber) - demand pump selector positioned to OFF or AUX, demand pump commanded to operate and output pressure is low

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What does the ENGINE driven Pump PRESS Light indicate when illuminated?

Illuminated (amber) - low engine hydraulic pump pressure.

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How is the hydraulic synoptic display accessed?

To view the hydraulic synoptic, push the HYD synoptic display switch on the display select panel.

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What should be noted about the hydraulic synoptic display’s representation of power flow?

The hydraulic power flow displayed is generated by the displayed valve positions, pump status, and fluid levels. It does not display actual hydraulic power flow, therefore the display may not represent actual system operation.

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How many independent hydraulic systems does the Boeing 747 have?

The airplane has four independent hydraulic systems, numbered by the engine which powers it.

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What components are powered by the hydraulic systems?

primary flight controls
autopilot servos
spoilers
stabilizer trim
elevator feel
landing gear
flaps
brakes
steering

N756CA, N702CA, N729CA
thrust reversers

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What primarily powers each hydraulic system?

Each system is powered by an engine driven pump (EDP).

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When is an Engine Driven Pump (EDP) pressurized?

The EDP is pressurized when the engine is running and the engine pump switch is ON.

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What is the role of the demand pumps in the hydraulic systems?

The demand pumps supply normal system demands if an engine or EDP fails.

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What type of demand pumps are installed in hydraulic systems 1 and 4?

Systems 1 and 4 have air driven demand pumps.

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What type of demand pumps are installed in hydraulic systems 2 and 3?

Systems 2 and 3 have electric motor driven demand pumps.

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When do demand pumps operate if their selector is in the AUTO position?

In the AUTO position, the demand pumps operate during periods of high system demands, such as flaps in transit or gear retraction.

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What is the purpose of the auxiliary pumps in the hydraulic systems?

N729CA, N952CA, N919CA, N756CA, N702CA, System 4 has an electric auxiliary pump for ground handling operations. N936CA, N663CA, N537CA, N569CA (if AUX 1 pump installed), Systems 1 and 4 have electric auxiliary pumps for ground handling operations.

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How is hydraulic fluid supplied to each system?

Independent reservoirs supply fluid to each hydraulic system.

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How are the hydraulic reservoirs pressurized?

The bleed air system pressurizes the reservoirs to prevent pump cavitation and ensure positive flow during high demand conditions.

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What does the RSVR PRESS indication signify on the synoptic display?

RSVR PRESS displays next to the synoptic reservoir symbol when reservoir bleed air pressure is low.

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What do the letters RF indicate next to the reservoir quantity indication?

The letters RF display next to the reservoir quantity indication when refill is required.

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What happens to the RF indication in flight when a low quantity is detected?

RF is inhibited in flight and replaced with the letters LO when a system low quantity exists.

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What is the function of the Hydraulic Interface Module (HYDIM)?

Each hydraulic system has a dedicated hydraulic interface module (HYDIM) to process temperature and pressure inputs as well as perform some pump control.

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What indications may occur if a HYDIM fails?

-Blank hydraulic pressure and temperature indications on the EICAS status andHYD synoptic pages,
-HYD CONTROL X advisory messages

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What does the Hydraulic Quantity Interface Module (HYQUIM) do?

A single hydraulic quantity interface module (HYQUIM) processes quantity inputs from each reservoir transmitter.

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What false indications might appear if the HYQUIM fails?

Should the HYQUIM fail the following false indications may occur for all four hydraulic systems: hydraulic SYS FAULT lights flashing on and off, >HYD QTY LOW X advisory messages appearing and disappearing, EICAS hydraulic quantity indications decreasing and increasing

What occurs in the hydraulic system when an engine fire switch is pulled?

If an engine fire switch is pulled, the respective hydraulic fluid shutoff valve closes, the EDP depressurizes, and the respective demand pump operates.

Which hydraulic systems power the autopilot servos?

Systems 1, 2, and 3 power the respective center, right, and left autopilot servos.

Which hydraulic systems power the spoilers?

Systems 2, 3, and 4 power spoilers.

Which hydraulic systems power the trailing edge flaps and landing gear?

Systems 1 and 4 power trailing edge flaps and landing gear.

Which hydraulic systems provide redundant power to the primary flight controls?

Systems 1 and 4 provide redundant power to primary flight controls.

Which hydraulic systems power the alternate brakes?

Systems 1 and 2 power alternate brakes.

Which hydraulic system powers the steering?

System 1 powers steering.

Which hydraulic system powers the normal brakes?

System 4 powers normal brakes.

Which hydraulic systems power the thrust reversers on specific aircraft?

N756CA, N702CA, N729CA, Systems 1, 2, 3, and 4 power respective thrust reversers.

What does the HYD CONTROL 1,4 advisory message indicate?

Hydraulic control system is inoperative. Hydraulic system indications may be inoperative.

What does the HYD OVHT SYS 1,2,3,4 advisory message signify?

Excessive hydraulic system temperature.

What does the HYD PRESS DEM 1,2,3,4 advisory message indicate for aircraft N729CA, N952CA, N919CA, N756CA, N702CA?

Demand pump pressure is low. Occurs when Demand Pump selector OFF, demand pump commanded to run and demand pump output pressure low, or system 4 Demand Pump selector is in AUX. Inhibited by HYD PRESS SYS message in a system low-pressure condition.

What does the HYD PRESS ENG 1,2,3,4 advisory message indicate?

Engine pump output pressure low. Inhibited by HYD PRESS SYS message in a system low-pressure condition.

What does the HYD PRESS SYS 1,2,3,4 caution message signify?

Loss of hydraulic system pressure.

What does the HYD QTY LOW 1,2,3,4 advisory message indicate?

Hydraulic quantity low.

When will the demand pumps operate if the hydraulic demand pump selector is in the AUTO position?

- EDP pump output pressure is low - Fuel control switch is in CUTOFF - Demand pumps 1 & 4 also operate when flaps are in transit, or flaps extended past 1

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?

* 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 * Example: Wheel Braking for towing.

Why are the hydraulic reservoirs pressurized by the bleed air system?

* To prevent pump cavitation | * To ensure positive flow during high demand conditions

If engine-driven pumps are operating normally, demand pumps 1 and 4 also operate?

- when flas are In transit on the ground. | - Flaps out of 1 in flight.

How does pulling FIRE Switch affect HYD SYS?

- EDP SOV closes - EDP Depressurizes - Related demand pump operates

Which HYD systems provide redundant power to primary flight controls?

SYS 1 and 4

HYD systems power primary flight controls?

SYS 2 and 3

HYD systems for upper/lower YD?

Upper - HYD SYS 3 Lower - HYD SYS 2

HYD system for stab trim and elevator feel?

HYD SYS 2 and 3

Which HYD systems power AP servos L, C, and R?

L = HYD SYS 3 C = HYD SYS 1 R = HYD SYS 2

Which HYD systems power the spoilers?

HYD SYS 2,3, and 4

Gear retraction HYD systems (numbered)?

1 4 | | 4 1

Speedbrake/Spoiler HYD systems (numbered)?

3-2-2-3 4-4 | | 4-4 3-2-2-3

Trailing Edge Flaps HYD systems (numbered)?

4-1 | | 1-4

PRESS amber light on engine pump switch?

Low engine HYD pump pressure

What happens when Demand Pump selector is placed in AUX position?

Pressurizes SYS 4 on the ground if GROUND HANDLING BUS is powered.

Aileron HYD SYS (numbered)?

(1/2)_(1/3) | | (4/2)_(4/3)

Nosewheel and Body Wheel Steer HYD SYS?

HYD SYS 1

Wheel Brakes HYD SYS?

NORM - SYS 4 Auto brake / anti-skid ALT - SYS 1. No Autobarke / anti-skid ALT - SYS 2. No Autobarke / anti-skid Altérnate with Anti-Skid only lateral pairs of brakes front or back pair on each truck

Elevator HYD SYS (numbered)?

(1)_(1/2) | | (3/4)_(4)

Upper Rudder HYD SYS (numbered)?

1 | 3

Lower Rudder HYD SYS (numbered)?

2 4

What 4 monitors are observed when HYD SYS 4 - AUX ON?

- SYS FAULT Light OFF - PRESS Light ON - BRAKE SOURCE Light OFF - ACCUMULATOR PRESS in GREEN band

What HYD SYS pressurized the BRAKE ACCUMULATOR?

HYD SYS 4

When will AUX Pump #4 stop its operation with the switch in the AUX position?

When the #4 EDHP is pressurized. * EICAS: HYD PRESS DEM 4 displayed

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.

What may cause the nose to pitch up on landing with the loss of hydraulic system 4?

Rapid extension of the Spoilers.

What are some examples of major system components powered by each hydraulic system 1 and 4

• Systems 1 and 4 power the steering body gear normal brakes (SYS 4), alternate brakes (SYS 1), trailing edge flaps Systems 1 and 4 also provide redundant power to the primary flight controls.

What are some examples of major system components powered by each hydraulic system 2 and 3

• Systems 2 and 3 power the primary flight controls stabilizer trim elevator feel. System 2 also powers the alternate brakes lower yaw damper. System 3 powers the upper yaw damper.

What are some examples of major system components powered by each hydraulic system 1, 2 and 3

• Systems 1, 2, and 3 power the respective center, right, and left autopilot servos (L,C,R are powered by systems 3,1,2 respectively)

What are some examples of major system components powered by each hydraulic system 2, 3 and 4

• Systems 2, 3, and 4 power the spoilers.

What are some examples of major system components powered by each hydraulic system System 1 and 4? Systems 2 and 3? Systems 1, 2, and 3? Systems 2, 3 and 4?

• Systems 1 and 4 power the trailing edge flaps, body gear, normal brakes (SYS 4), alternate brakes (SYS 1), and steering. Systems 1 and 4 also provide redundant power to the primary flight controls. • Systems 2 and 3 power the primary flight controls, stabilizer trim, and elevator feel. System 2 also powers the alternate brakes and lower yaw damper. System 3 powers the upper yaw damper. • Systems 1, 2, and 3 power the respective center, right, and left autopilot servos (L,C,R are powered by systems 3,1,2 respectively) • Systems 2, 3, and 4 power the spoilers.

Hydraulic Flashcards

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