hydraulics

There are 4 independent hydraulic systems driven by:

EDPs (engine driven pumps) and demand pumps — Each hydraulic system has two parallel pressure sources: an engine-driven pump and a demand pump. The FCOM wording is “Each system is powered by an engine driven pump and a demand pump installed in parallel.” [Ref: FCOM 13.20.1]

Systems 1 and 4 have demand pumps of which type?

ADP (air driven) — Systems 1 and 4 use pneumatic power for their demand pumps. The FCOM states: “Systems 1 and 4 have air driven demand pumps.” [Ref: FCOM 13.20.1]

Systems 2 and 3 have demand pumps of which type?

ACMP (AC electric) — Systems 2 and 3 use electrically driven demand pumps rather than ADPs. The FCOM states: “Systems 2 and 3 have electric motor driven demand pumps.” [Ref: FCOM 13.20.1]

The ____ AUX pump works with system fluid.

4 — The auxiliary pump belongs only to hydraulic system 4. The FCOM states: “System 4 has an electric auxiliary pump for ground handling operations.” [Ref: FCOM 13.20.1]

The AUX pump is operated by a ____ system.

Electric — The AUX pump is electrically driven; it is separate from the air-driven demand pump on system 4. The FCOM calls it an “electric auxiliary pump.” [Ref: FCOM 13.20.1]

The AUX pump can be used both on the ground and in the air. True or False?

False — False. AUX is a ground-handling function: with AUX selected, the “auxiliary pump operates on ground until respective engine driven pump pressurizes.” It is therefore not an in-flight auxiliary source. [Ref: FCOM 13.10.1]

What hydraulic system powers the alternate brakes and the body gear steering system?

System 1 only — The system description identifies the relevant source/actuation: “747 Flight Crew Operations Manual Preface - Revision Highlights Boeing Proprietary.” That is why the correct source is System 1 only. [Ref: FCOM 13.20.2]

What hydraulic system powers the respective autopilot servos?

3 - Left Autopilot; 1 - Center Autopilot; 2 - Right Autopilot — The system description identifies the relevant source/actuation: “747 Flight Crew Operations Manual Preface - Revision Highlights Boeing Proprietary.” That is why the correct source is 3 - Left Autopilot; 1 - Center Autopilot; 2 - Right Autopilot. [Ref: FCOM 13.20.2]

What causes the EICAS message HYD PRESS DEM to remain displayed after the selector has been placed in the ON position?

Pump pressure low [Ref: FCOM 13.30.1]

Select the correct statement:

Demand pumps 1 & 4 operate pneumatically. Electric power is required for EDP aux pump [Ref: FCOM 13.20.1]

The electric AUX pump in system 4:

Will produce normal brake pressure when on the ground — The system description identifies the relevant source/actuation: “Auxiliary Pump(s) System 4 has an electric auxiliary pump for ground handling operations.” That is why the correct source is Will produce normal brake pressure when on the ground. [Ref: FCOM 13.20.1]

Demand selector 4 is in AUX. Select the correct statement.

The AUX pumps stops when EDP provides pressure [Ref: FCOM 13.30.1]

The EDPs cannot deliver hydraulic pressure:

While engines are not running, when the engine pump is not switched ON, and when the engine fire switch is pulled [Ref: FCOM Chapter 13 — Hydraulics]

With flaps in landing position during approach:

HYD 1 and 4 demand pumps activate [Ref: FCOM 13.20.1]

Engine 3 is shut down due to a fire warning, the fire switch is pulled, and fuel control switch 3 is in CUTOFF. Select the correct statement:

EDP depressurizes, the respective demand pump operates, and SOV 3 closes [Ref: FCOM Chapter 13 — Hydraulics]

You are on approach selecting flaps 5. HYD PRESS DEM 1 message appears. What should be done?

Possible auto logic failure - turn HYD 1 demand pump ON [Ref: FCOM Chapter 13 — Hydraulics]

Which abnormal condition does NOT trigger the SYS FAULT light?

System reservoir pressure low — The FCOM describes the triggering logic as “3 Hydraulic System (SYS) Fault Light Illuminated (amber) - • low hydraulic system pressure • low hydraulic reservoir quantity.” Those are the conditions that lead to System reservoir pressure low. [Ref: FCOM 13.10.1]

The beeper sounds and hydraulic SYS FAULT light 2 is on. Which message triggers the EICAS caution alert?

HYD PRESS SYS 2 [Ref: FCOM Chapter 13 Section 30]

During flap extension while taxiing out, SYS FAULT light 4 illuminates and HYD OVHT 4 appears. What describes the situation correctly?

Excessive hydraulic temperature detected; above 105°C may indicate an overheated pump [Ref: FCOM Chapter 13 — Hydraulics]

What conditions would cause the DEMAND pumps to operate with the selector in AUTO?

Respective engine output pressure low or fuel control switch in CUTOFF [Ref: FCOM 13.10.1]

When the #1 EDP switch is ON, when will the #1 engine produce hydraulic pressure?

When the engine rotates — The condition/timing specified by the card is: When the engine rotates. [Ref: FCOM 13.20.1]

What condition would automatically command hydraulic demand pumps #1 and #4 to operate?

TE flaps in transit, or flaps extended with engines at IDLE [Ref: FCOM 13.10.1]

What causes the EICAS message HYD PRESS DEM 4 to be displayed?

Selector in AUX position after ENG startup [Ref: FCOM 13.30.1]

The hydraulic demand pump in System 4 is disabled when the System 4 demand pump selector is in the AUX position. True or False?

True [Ref: FCOM 13.30.1]

With a HYDRAULIC system 1 failure, what capability is lost?

Center autopilot, inboard TE flap, nose & body steering actuation, and left outboard elevator [Ref: FCOM Chapter 13 — Hydraulics]