Landing Gear Systems (A330)

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Questions and Answers

Which condition is NOT required for alternate braking to be active in flight?

G HYD pressure insufficient

Antiskid N/W Switch ON

Parking brake ON (correct)

BLUE HYD pressure available

The initial brake force in alternate braking mode is lower than in normal mode.

False

What do pilots need to modulate brake pressure at or below to avoid wheel locking when antiskid is deactivated?

1000 PSI

Accumulators are designed to supply ___ full brake applications.

7 Signup and view all the answers

Match the following autobrake settings with their deceleration rates:

LO = 1.8 m/s² MED = 2.65 m/s² MAX = 3.0 m/s² ON DECEL = shows positive arming Signup and view all the answers

What happens if the green hydraulic pressure is lost during the use of the parking brake?

Blue system takes over brakes Signup and view all the answers

The MAX autobrake setting is typically used for takeoff.

True Signup and view all the answers

What must happen for automatic switching to alternate braking to be achieved?

An auto hydraulic selector is required Signup and view all the answers

What is required for the autobrakes to activate in LO/MED mode?

Green hydraulic pressure available Signup and view all the answers

Autobrakes can activate below 72 knots due to ground spoilers not extending.

True Signup and view all the answers

What is the primary purpose of the BSCU in the braking system?

To control all braking modes and functions. Signup and view all the answers

The ________ gear and main L/G deploy by gravity.

nose Signup and view all the answers

Match the following braking modes with their descriptions:

Normal Braking = Antiskid operative, brakes operate via pedals Alternate Braking = Uses blue hydraulic system Autobrake = Automatically activates with ground spoilers Anti-Skid = Prevents wheel skidding during braking Signup and view all the answers

Which condition will NOT disarm the autobrakes?

Brakes being released Signup and view all the answers

The anti-skid system remains operational even at low speeds.

False Signup and view all the answers

What happens when brake release orders are given in the anti-skid system?

Brakes are released to prevent skidding. Signup and view all the answers

What mechanism reduces the main gear length during retraction?

Shortening mechanism Signup and view all the answers

The nose landing gear retracts backwards toward the fuselage.

False Signup and view all the answers

What is the primary purpose of the hydraulically operated pitch trimmer on each boogie?

To damp movement and ensure return to normal position after lift off. Signup and view all the answers

The landing gear position indicators are provided by __________.

LGCIU 1 Signup and view all the answers

Under what conditions does the L/G selector lever lock in the 'Down' position?

When both main landing gear shock absorbers are compressed. Signup and view all the answers

What happens to the main and nose landing gear during a gravity extension?

They extend by gravity. Signup and view all the answers

Match the following components with their functions:

Pitch trimmer = Stabilizes movement after lift off Cut-out valve = Isolates hydraulic system during gravity extension Locking springs = Assist downlocking of gears Anti-skid brake = Prevents wheel lock during braking Signup and view all the answers

What is the primary role of the LGCIU during landing gear operation?

Switch over after one complete gear cycle Signup and view all the answers

Study Notes

Landing Gear (A330)

Main Landing Gear: Each main landing gear has four wheels, twin tandem boogie assembly, and oleopneumatic shock absorbers.
Wheel Components: Each wheel has an anti-skid brake and is fitted with a mechanism.
Main Gear Length Reduction: Hydraulically operated pitch trimmer on each boogie retracts the shock absorber into the main leg during retraction, reducing main gear length.
Nose Landing Gear: Two nose wheel oleopneumatic strut steering system wheels retract forward to the fuselage.

L/G Operation

Gear and Door Sequencing: Gear and door sequencing is electrically controlled by the LGCIU's.
LGCIU Operation: Each LGCIU has switches; after one complete gear (or in each case of a failure, 4G) retraction, each completes a cycle.
Hydraulic Activation of Gears and Doors: All gears and doors are hydraulically activated by the green hydraulic system.
Safety Valves: Safety valves isolate the hydraulic supply.
Position Indicators: Landing gear position indicators on the center panel are provided by LGCIU 1 (even if LGCIU 2 is controlling the gear cycle.)
Speed Limit: Above 280kts

Gravity Extension

Gravity Extension System: The gravity extension system is controlled through two selectors.
Electro-Mechanical System: Electro-mechanical systems are located in the center instrument panel.
Gear Door Operation: When the electrical L/G hydraulic system is isolated by the green selector, the main and nose landing gears, and doors, are extended by gravity. Locking springs assist in downlocking. During free fall operation, it's possible to restore normal hydraulic operation provided the green hydraulic pressure is available.
Nose Landing Gear and Doors: Main and nose landing gears and doors remain open.

L/G Selector Lever

Two-Position Selector: The two-position selector has electrical signals to 2 LGCIU.
Up Position: Retraction of gear
Down Position: Interlock mechanism prevents unsafe retraction of the lever. The position of the MLG and N/LG shock absorbers is crucial; when the lever is down, the wheel bogies are compressed, and the lever must be extended on the ground.
Warning: A red arrow with ECAM warning in the approach, at 750 H RA, if the L/G are not down locked in landing configuration.

Gravity Extension (Continued)

Actuators: Two motorized actuators close the hydraulic cut-off valve to close doors and disengage nose gear, which permits the main L/G to deploy automatically and lock-down.

General

Braking System: Normal brakes use green hydraulics; alternate brakes use blue hydraulics.
Channel and Controls: Dual channel BSCU controls all braking modes and functions. Normal, alternate, Autobrake, and Antiskid braking.

BSCU Channel Selection

Changes at Each L/G Down Failure: Changes in the BSCU channel selection occur at each landing gear (L/G) down failure.
Anti-skid system: Main L/G has fusible plugs, cooling fans, and anti-skid.
Normal/Alternate Servo Valves and Auto Brake: Anti-skid brake servo valves, normal/alternate servo valves and auto brake system.
Full Braking Performance: Performance is achieved only at full pedal deflection, and when without auto brake, the system shows released brakes.
Antiskid System operation: Comparisons of speed, deceleration, and deceleration orders are essential during antiskid operation. If deceleration is less than 0.88, brake release orders are released.

Auto Brakes

Arming Conditions: Auto-braking systems deploy when the green hydraulic pressure is electrically available and there's no failure in the braking system; at least 2 PRIMS are available with at least one Adiru.
Autobrake Activation: The autobrakes activate at the command of the ground-based spoilers.
Spolier Deployment: Spoiler deployment extends before the speed reaches 40kts
Autobrake Deactivation: When the spoilers extend below 72kts, the autobrakes do not initiate.
Autobrake Disarming: Autobrakes are disarmed via reversing the arming condition and releasing the parking brakes.

Auto Brakes (Continued)

Parking Brakes: Repressing the brakes' arming condition, when the activation condition satisfies the autobrake deflection condition at one brake pedal, these autobrakes are active during take-off and touch-and-go.

Operation

Normal Braking: Antiskid, auto-brakes, and green hydraulic pressure are required for normal braking.
Alternate Braking: If green hydraulic pressure is insufficient and blue hydraulic pressure, with the antiskid switch on and the NW (nose wheel) and parking brake activated, then alternate braking is activated. If either antiskid or NW is not available, then alternate braking is not available.
Parking Brake: Parking brakes are supplied by blue hydraulic system.
Normal Braking and Brake Pedals: Brake application is via brake pedals.
BSCU: BSCU automatically controls the alternate brake via the alternate servo valves.
Pressure Indication: Brake and accumulator pressure is indicated on the triple indicator.

Auto Brake Panel

Arming Procedure: Push buttons to deploy the ARM followed by LO/MED/MAX for takeoff deceleration.
Deceleration Modes: Selected for takeoff, Landing, and Progressive Pressure Deployments are for deceleration and ALC.
Deceleration Rate: when the autobrake is active correspond to the 80% of selected Rate (2.65m/s)

Automatic Switching

Alternative Braking: Automatic switching to alternative braking via an auto hydraulic selector controlled by BSCU and control via alternate servo valves.
Pressure Indication: Brake and accumulator pressure is indicated on the triple indicator during the mode.
Alternative Braking: Alternative braking operates without antiskid when antiskid and autobrakes are inoperative.
Antiskid Deactivation: Electricity (A/SKID N/W ST SW off or Power supply failure or BSCU failure) or low pressure in hydraulic system (B+G), disrupts the antiskid system and activates alternative braking by using only the brake accumulator pressure.
Pilot Module Operation: Pilot must modulate the brake pressure at take off or landing to prevent wheel locking.

Parking Brake

Alternative Braking for Parking: Parking brake may initiate alternative braking via blue hydraulic while the antiskid system is not available.
A/SKID/N/W STRO: (A/SKID/N/W STRO) activates the available system if GREEN HYD is available.
Parking Brake Activation: Green HYD pressure lost; alternative braking commences; brake application is via brake pedals, and the antiskid/nose wheel is no longer available.
No Parking Brake: If the system does not detect that the Blue hydraulics with the antiskid is operational, then no parking brake is functional.

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Description

Test your knowledge on the landing gear systems of the A330 aircraft. This quiz covers the main landing gear, nose landing gear, operation of the landing gear control interface unit (LGCIU), and the hydraulic systems involved. Get ready to dive into the engineering behind airplane landing gear functionality.