B757 Landing Gear and HYDs

What does the SYS PRESS light mean on P5

System pressure low. <1200psi

What does the RSVR light mean on P5

Reservoir level low or Header pressure low

What does the PRESS light mean on P5

Pump pressure <1200psi

What does the OVHT light mean on P5 and at what temp does it come on

Pump overheat. 225°F

Where are the Hydraulic Reserviours

LH & RH wheel wells

Lower AFT LH wing to body faring.

Which components are feed from the stand pipes in each reservoir?

Left - PTU pump.

Right - Reserve Brakes.

Center - RAT.

What’s 2 ways is header pressure is created?

What’s a top tip when depressurising the header pressure?

Pneumatics & Manually charged

Use a rag over the valve to catch hyd fluid

How do you control the EDP Supply Shutoffs?

Engine fire handles

What do the Electrical Load Control Units do?

Gives a start time delay for ACMPs.

Limits center system to one ACMP when only one source of AC power available.

What pumps have an integral temp switch?

ACMPs @ 225°F

Where are the 3 System Pressure Switches?

LH & RH EDP Pressure/Case Drain Filter Modules

Center ACMP Pressure/Case Drain Filter Module

Where are the EDP and LH & RH Pressure/Case Drain Filter Modules located?

EDP - in the pylon

LH & RH - respective wheel wells

Where are the Case Drain Heat Exchangers located?

LH and Center System - LH main fuel tank

RH - RH main fuel tank

Where are the System Pressure Transmitters located?

LH and Center in left MLG wheel well

RH in right MLG wheel well

What will be indicated if a system pressure is below 2800psi for more than 60s with both engines running

EICAS message

What are the 3 ways to check hyd levels

EICAS

Sight glass on reservoir

Remote triple indicator

What will happen if fluid temp reaches 225°F?

OVHT light

EICAS message

How much overall LH EDP output does the PTU create?

80%

What things does the PTU supply HYD power

Flaps

Slats

Landing Gear

NWS

Main Deck Cargo Door

HMG (Hydraulic Motor Generator)

What 3 ways is the PTU activated?

Left eng N3 drops below 53% while right eng operates

Left EDP drops below 1275psi while right eng operates

Manually on ground via switch on P61

What are the 2 switches on the PTU Pressure Filter Module?

Control

Indication

What 3 times will the RAT deploy

dual engine failure above 80kts

Switch on P5

Right MLG wheel well controls

How do you retract the RAT

Right MLG wheel well controls

Where is the HMG (Hydraulic Motor Generator) located?

Left MLG wheel well keel beam

When will HMG activate?

Automatically when power is lost to both AC busses

Which components of the Main Cargo Door are located in the wheel well

Shutoff vale

Control valve

Hand pump

What is the purpose of the MLG Reaction Link?

Transfer lateral load back to structure

What does the Rebound Restrictor do?

Controls the rate of strut extension

What is the MLG Truck Droop Angle?

12°

Under Alternate Extention what controls the MLG Doors

Actuator Lock is released and doors free fall

What are the 3 extra parts of the NLG other than the Shock Strut?

Upper Drag Strut

Lower Drag Strut

Lock Link

How are the NLG doors actuated?

Aft Doors are mechanically linked to the shock strut

Fwd Doors are hydraulically sequenced

What are 3 features of the Control Leaver Module

Three position (Up, Off, Down)

Sprung loaded

Solenoid operated lever lock

Explain MLG Uplock features

2 hydraulic actuators for normal and alternate operation

What component has internal flow limiters to control NLG speed

NLG Retract Actuator

How is Alternate Gear Extension actioned?

Switch on main instrument panel

From where is fluid supplied to the Power Pack

Left System Return

What is sprung loaded and returns to normal position when alternate pressure is depleted?

Door release actuators

What is the purpose of Door Safety Valves?

To prevent unintentional closing of the doors when they are opened for maintenance

What is indicated when the Door Safety Valves are not in the ‘safe’ position?

Red light in each wheel well

An integral solenoid in the Door Release Interlock Actuators is controlled by the Door Close Switch and what else?

Selecting landing gear leaver to up

What does the DOORS light mean?

Doors are not closed

What does the GEAR light mean

disagreement

What proximity switches does the MLG have?

2x down lock

2x up lock

What proximity switches does the NLG have?

2x on lock link (locked)

2x on upper drag link (position)

What is the tiller input vs output

360° tiller gives 65° steering

How is the Rudder Pedal Steering Interconnect Mechanism linked to the Steering Cable?

Quadrant

What is purpose of Broken Cable Compensator?

Prevents damaged cables making un-commanded input to the steering

What is a function of the Steering Metering Valve Module?

Sprung loaded to a neutral position

What are the Normal and Alternate Brake systems powered by?

Normal - Right

Alternate - Left

When does the Alternate Brake Selector Valve initiate alternate brakes?

If the right system pressure drops to 48% of the left

What will the indications be when both brake systems fall below 48%?

BRAKE SOURCE light on P1

EICAS message

What is the Actuator associated with the Dual Brake Metering Valve Assemblies?

De-spin actuator - gently applies brakes when landing gear leaver is set to up

What is the difference between Normal and Alternate Anti-skid?

Normal - controls wheels individually

Alternate - controls wheels in lateral pairs

What are the 4 types of Anti-skid

Wheel deceleration control

Hydroplane/Touchdown protection

Locked wheel protection

Gear retract inhibit

What is deactivates and controls the deactivation to allow de-spin to happen and for how long?

Gear retract inhibit deactivates Touchdown protection for 12.5 secs

Where is the Anti-skid/Auto Brake control Unit?

E5

What does the Anti-skid Shuttle Valve Module do?

Shuttles between Normal and Alternate brakes

How doe the Auto Brake system know the required braking effort?

IRS speed data

Average wheel rpm

Name a few conditions where Autobrakes are disarmed

Throttles advanced

Anti-skid fault

Autobrake fault

Pilot applied manual brakes

What system is used for the Park Brake and Accumulator?

Right

When landing gear leaver is in down position what things are pressurised?

NLG doors, lock

MLG lock, truck tilt, doors

When landing gear leaver is in up position what is pressureised

NLG doors, lock, retract actuator

MLG doors, truck