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11.1

LANDING GEAR

11.1 GENERAL

11.2 MAIN LANDING GEAR

11.2.1 MAIN COMPONENTS – SPECIFICATIONS

11.3 NOSE LANDING GEAR

11.3.1 MAIN COMPONENTS - SPECIFICATIONS

11.3.2 AUTOMATIC CENTERING OF NOSE WHEELS - ANTI-SHIMMY DEVICE

11.3.3 NOSE WHEEL CENTER LOCKING

11.4 RETRACTION ACTUATOR CYLINDERS

11.5 L/G RETRACTION/EXTENSION HYDRAULIC SYSTEM - PRINCIPLE

11.6 L/G RETRACTION/EXTENSION CONTROLS AND INDICATORS

11.7 L/G OPERATING ELECTRICAL CIRCUITS

11.7.1 GENERAL DIAGRAM OF L/G

11.7.2 FUNCTIONNAL ANALYSIS OF L/G POSITION MICROSWITCHES

11.7.3 L/G NORMAL RETRACTION/EXTENSION CONTROL SYSTEM OPERATION

11.7.4 L/G INDICATING SYSTEM

11.8 POWER-ASSISTED BRAKES11.8.1 SYSTEM DESCRIPTION & SPECIFICATIONS

11

Ce document est la propriété d'EUROCOPTER ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite

d'EUROCOPTER et son contenu ne peut être divulgué. This document is the property of EUROCOPTER ; no part of it shall be reproduced or transmitted

without the express prior written authorization of EUROCOPTER and its contents shall not be disclosed. © EUROCOPTER 06-2005.

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11.2

List of effective pages

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11.3

11.1 GENERAL

EACH LANDING GEAR UNIT COMPRISES

• A leg (oleo shock strut) that absorbs the energy upon touch-

down, damps taxiing vertical accelerations and the rotor induced

oscillations during starting and stopping.

• A hydraulically controlled retraction actuator.

THE NOSE LANDING GEAR UNIT

with a 360° rotation castering L/G is equipped with :

- a friction anti-shimmy device

- a system which automatically returns wheels tocenterline and an optional wheel locking device controlled

from the cockpit.

THE MAIN LANDING GEAR

is equipped with hydraulically controlled disc brakes. If L/

G retracted, main L/G compartments are closed by two

doors controlled by the L/G movement.




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11.4

9 -L/G complete extension detection microswitch

(Electrically inhibits L/G retraction when aircraft

is on ground)

10 -L/G compartment side door control roller

11 -Scissors

12 -Wheel

13 -Tubeless tire

14 -Disc brake15 -Shock absorber piston rod

16 -Body

17 -Disc brake supply line

1 -L/G pivot shaft

2 -Inflation valve of "high pressure” nitrogen chamber

of oleo pneumatic shock absorber

3 -”Low pressure” nitrogen chamber inflation valve

4 -L/G position microswitch (detection of L/G locking in

down position)

5 -Microswitch (4 - 6) wirings

6 -L/G position microswitch (detection of L/G locking inup position)

7 -Actuator (8) supply line

8 -Retraction cylinder

11.2 MAIN LANDING GEAR

11.2.1 MAIN COMPONENTS – SPECIFICATIONS

• All L/G hinges are self-lubricated and do not require lubrication

• Microswitches (4 - 6) are controlled by the retraction actuator piston

• Microswitch (9) is controlled by the shock absorber piston rod (15)

23 4

5 6

7

8

9

10

11

1213

14

15

16

17

1




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11.5

11.3.1 MAIN COMPONENTS - SPECIFICATIONS

1 -L/G pivot shaft on structure

2 -Shock absorber nitrogen chamber inflation valve

3 -Retraction cylinder

4 -Wheel castering lock

5 -Shock absorber piston rod

6 -Wheels

7 -Scissors

8 -360° rotating tube (shock absorber cylinder)9 -Yoke

1 2 1

3

4

8

5

6

7

9

11.3 NOSE LANDING GEAR




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11.6

11.3.2 AUTOMATIC CENTERING OF NOSE WHEELS - ANTI-SHIMMY DEVICE

ANTI-SHIMMY DEVICE

The friction of two discs (5-6) creates the anti-

shimmy effect. Disc (5) is integral with the shockabsorber rotating cylinder (8). Disc (6), integral

with the strut assy (7) is fixed. Disc friction in-

creases according to the load on the wheels.

5

«WHEEL CASTERING» AND

«EXTENDED L/G» DETECTION

The microswitch (9) that inhibits L/G re-

traction on groud, is controlled by the clevis

(11) via a "link-bellcrank-pushbutton" de-

vice (10). After take-off, (wheels on aircraft

centerline and shock absorber completely

extended) switch inversion cancels the L/G retraction inhibition.

The cam (2), integral with the shock absorber piston rod (3) is mo-bile. The cam (4), integral with the tube level (1)hence with the strut

assy, is fixed.

With the shock absorber compressed (aircraft on ground), the mobile

cam driven by the piston rod, is separated from the fixed locating cam

and the wheels freely rotate according to the aircraft movements.

During shock absorber extension (take-off), the mobile cam comes in

contact with the locam and by matching the profile, repositions the

wheels on aircraft centerline.

Repositioning device is effective over ± 170°

Wheels on aircraft centerline

9

10

11

6

1

7

8

3

1

2

3

4

WHEEL CENTERING

SHOCK ABSORBER

COMPRESSED

SHOCK ABSORBER

EXTENDED




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11.7

11.3.3 NOSE WHEEL CENTER LOCKING

This mechanism prevent rotation of the nose gear during landing on a moving platform or on sloped ground. The

mecanism is composed of :

• 1 centering shear pin (3), actuated by a handle (6).

• 1 spring (2) which locks the mechanism.

• 1 manual cable control (1).

• 1 flag (4) appearing when the gear is locked in order to prevent false maneuver (towing with gear center-locked)

LOCKED UNLOCKED

6

7

PRESENT CONTROL HANDLE POSITION

"NOSE LANDING GEAR UNLOCKED"

1 -Control cable

2 -Spring

3 -Locking pin

4 -Safety flag

5 -Bellcrank

6 -Locking handle

7 -Parking brake handle

The assembly is designed so that the control can be armed

regardless of the nose wheel position with respect to the

aircraft centerline, locking is accomplished during auto-

matic wheel centering

Moreover, should cable fails, the nose wheel will auto-

matically be centered and locked.

To "LOCK" or "ARM" the wheel locking device : push

and turn the handle 90° clockwise.

To unlock the nose wheel, push handle downwards then

turn 90° anticlockwise and push down.

DO NOT CONFUSE locking handle (6) with parking brake

handle (7)

6

5

1

2

34

4 3

2




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11.8

11.4 RETRACTION ACTUATOR CYLINDERS

Landing gear retraction rearwards is obtained by retraction of hydraulic cylinders. "L/G up" and "L/G down" positions

are locked mechanically (claw lock). Positive locking is detected by "L/G up" and "L/G down" microswitches.The main

and nose landing gear actuators are of the same design and differ only in their lengths.

Gear unlocked "up"

Gear locked "up"

LOCKING PRINCIPLE AND LOCKING DETECTION

(L/G up side shown, same for L/G down side)

ACTUATOR CYLINDER OPERATION

- Actuator retraction (the figure shows the actuator at the end

of its retraction travel) : fluid inlet at B and return via A

- Retraction chamber E is pressurized. The extension

chamber D is open to return line. the rod retracts.- Actuator extension : fluid inlet at A (normal extension)

or at C (emergency hydraulic system extension) and

return via B : the rod extends.

- Locking : at the end of travel (retraction or extension :

the two locks are opposite hand) bushing (7) separates

the locking claws (8). When the bushing reaches its

stop, the claws fall back onto its shoulder. Spring (4)

then pushes cap (5) which covers the claws holding

them in "locked" configuration. When the actuator is

locked microswitch (3) trips cutting off the hydraulic

power supply.

- Unlocking : the actuator power suppliy pressure,greater than the force of locking spring (4), pushes back

cap (5) which releases the spring locking claws... The

rest of the operation is clear.

1 -"L/G down" microswitch

2 -Shuttle valve

3 -"L/G up" microswitch

4 -Locking spring

5 -Locking cap

6 -Actuator cylinder

7 -Locking bushing

8 -Spring locking claws

9 -Actuator rod

E 9

2

D 8

4 5 6 7

BC A

1

2 3

3

9

5




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11.9

11.5 L/G RETRACTION/EXTENSION HYDRAULIC SYSTEM - PRINCIPLE

Electrical control system operation is described later. The figure shows solenoid distributor (2)

deenergized: the two chambers of each actuator are connected to the return lines.

LH hydraulic power system ensures normal L/G retraction

and extension maneuvers. The hydraulic pressure is sup-

plied from the L/G distribution unit 820G (A). A solenoid

valve (1) delivers the pressure to a dual control solenoid

distributor 15 G (B) supplying the extension or retractionactuator chamber. The emergency hydraulic power system

ensures emergency L/G extension.

- L/G RETRACTION : Solenoîd (a) of dual control solenoid

distributor (B) is energized and supplies the actuator re-

traction chamber. Solenoid (b), deenergized, connects the

extension chambers to the return lines.

Retraction

Normal extension

Emergency extension Retraction

Emergency

extension

Normal

extension

5µ

P2 l

PC

A

B

1

ab

3 3

4

4

HYDRAULIC CIRCUIT

M AIN UNIT

140 b27l / mn

125b

1 l/mn

0.6 l

50 bL ANDING GEAR

DISTRIBUTION UNIT

Extension

Wheel

brakes

R

R

R

4

3

Extension

Retraction

- NORMAL L/G EXTENSION : The hydraulic distribution

is reversed. Solenoid (b) is energized and (a) is

deenergized.

- EMERGENCY L/G EXTENSION : The emergency

hydraulic system electric pump 21 G (C) directly suppliesthe actuators via a shuttle valve (4), separating the "normal"

and "emergency" extension systems.

Normal L/G extension and retraction operating time is

adjusted by diaphragms (3).

NOTE




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11.10

11.6 L/G RETRACTION/EXTENSION CONTROLS AND INDICATORS

1 -"L/G not locked down" flashing indicator light (flashes

if L/G is not downlocked at IAS < 100 km/h (55 Kt)

2 -"L/G in operation" amber indicator light 3 -"Nose L/G downlocked" green indicator Iight

4 -"RH L/G downlocked" green indicator light

5 -"LH L/G downlocked" green indicator light

6 -Control flap (7) safety pin – Inserted on ground

7 -"Normal retraction/extension" control switch - Switch

control flap is locked in up and down

8 -3- way control switch :

- NORM : L/G "Normal retraction /extension" position

- EMERG : Emergency L/G extension position

- TEST : "Ground hydraulic power

9 - Indicator light test

10 -Dimmer

11 -L/G pump amber light

8

9

10

TEST

IND LTSCAUT/ADVY

DIM

L/GL.G PUMP1

24

5

6

7

11 1

3

L/G




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11.11

LANDING GEARDISTRIBUTION

UNIT

Main hydraulic system

In order to operate the L/G in the different configurations the following is necessary :

- the controls : they consist of L/G up or L/G down selector in normal mode, and in emergency extension control

- control devices such as the solenoid valves (2), (3), (4).

- detection devices located on the landing gear : they organize the movements and deliver to the pilot informations of

configuration. Those detection devices are multicontact microswitches (7), (8), (9).

- safety and defect devices integrated in the A.S.U. : prevent any wrong manoeuver (1).

- indicating items: they show to the pilot the configuration of the L/G (up, down, manoeuver).

11.7 L/G OPERATING ELECTRICAL CIRCUITS

1 - Electronic ancillary system unit

2 - L/G solenoid valve3 -Extension solenoid valve

4 -Retraction solenoid valve

5 -Low speed detection device (IAS > 55 Kts)

ASU ASU

Hydraulic system

Landing gear control

Flight/ground

logic

TNS* warning

A/S > 55Kt

(contact open)POWER SUPPLIES

1

2

3 4

5

10 Alpha 2 11 Alpha 2

L/G L/G

retracted

* TNS = L/G non extended

Retraction

L/G

L.G PUMP

L/G

69

10

8

11.7.1 GENERAL DIAGRAM OF L/G

7

6 - Landing gear : Centered and extended

7 -Shock Absorber Extended (SAE)8 -Landing gear : Locked down

9 -Landing gear : Locked up

10 -Landing gear : L/G SAE




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11.12

Unlocked

"up"

Locked

"down"

The position microswitches detect the following positions

- L/G "locked down "

- L/G in operation

- L/G "locked up"

Each retraction actuator has 2 microswitches : "L/G down" and L/G up" microswitches controlled by the actuator

piston rod. Switching occurs during actuator locking (locking up and down). The upper position of each microswitch

controls normal retraction and extension operation. The lower portion controls the indicator light system. The two

portions are electrically independent (dual cell design).

L/G LOCKED "DOWN"

- "L/G up" microswitch is in "L/G unlocked up"

position

- "L/G down" microswitch is in "L/G locked

down" position

L/G IN OPERATION

- both microswitches are in "L/G unlocked up

and down" position

L/G LOCKED "UP"

- "L/G up" microswitch is in "L/G locked up" posi-

tion

- "L/G down" microswitch is in "L/G unlocked

down" position

11.7.2 FUNCTIONNAL ANALYSIS OF L/G POSITION MICROSWITCHES

Unlocked

"up"

Unlocked

"down"

Locked

"up"

Unlocked

"down"




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11.13

RH/LD

CONTROL+

0

AND

T

2 s

ORLH/LD

13G

FDW/LD

7G

14G

DOWN

UP

Down-locked

11α 2

DOWN

UP

LANDING GEARDISTRIBUTION

UNIT (16G)

R

RetractionNormal

extension

11G

6G

12G

Gnd 10G

CONTROL

Ground safety

T

2 s

NORM.

EMERG.

TEST


3

Extension Retraction

Gnd 5G

Gnd 9G

D3

+

0

EMERG.

15G

820G

28VOR

28V

FDW/LU

LH/LU

RH/LU

RH/SAEFDW/SAELH/SAE

AND

1- 3 position switch (Normal -Emergency -Test)

2- "Normal" control cut off relay

3- Normal retraction /extension control switch

4- Electronic ancillary system unit 11 Alpha

5- 2 seconds closure time delay

6- Electronic ancillary system unit 10 Alpha

7- L/G solenoid valve

8- Normal extension solenoid distribution

11.7.3 L/G NORMAL RETRACTION/EXTENSION CONTROL SYSTEM OPERATION

11.7.3.1 SYSTEM COMPONENTS

9 -Normal retraction solenoid distribution

LH - Left hand L/G

RH - Right hand L/G

FDW - Foward Hand L/G

LU - Locked up

LD - Locked down SAE - Shock absorber extended

7

8

3

10 Alpha2

10 Alpha2

ASU

3

4

5

2

6

1

NOTE : The system is shown in "Aircraft on ground"

ASU

9




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11.14

ASU11α 2

10 α 2 ASU

When the aircraft leaves the ground microswitches 9G, 5G and 10G are tripped (shock absorber fully extended and

nose wheel locked): the L/G CAN BE RETRACTED.

When the control switch (1) is set to «retraction», the A.S.U 11 Alpha 2 supplies the solenoid valve 820G (2) and the

retraction solenoid distribution (3). The system is pressurized by the LH hydraulic system: the L/G RETRACTS.

Solenoid (2) and (3) will remain supply as long as the microswitches 11G, 6G and 12 G have not reach the "lock up"

(LU) position. This supply will be maintained 2 sec more to ensure a correct locking by the time delay closure (4).

11.7.3.2 L/G RETRACTION- "L/G DOWN" UNLOCKING

When control swich (1) is set to "extension", the A.S.U.11 Alpha 2 supplies the solenoid valve 820G (2) and the

extension solenoid distribution (3). The system is pressurized by the LH hydraulic system: the L/G EXTEND.

Solenoid (2) and (3) will remain supply as long as the microswitches 13G, 7G and 14G have not reach the lock down

(LD) position. This supply will be maintained 2 sec more to ensure a correct locking by the time delay closure (4).

11.7.3.3 L/G EXTENSION

11.7.3 L/G NORMAL RETRACTION/EXTENSION CONTROL SYSTEM OPERATION (Cont'd)

1

4

3

2

1

4

3

2

Gnd Gnd Gnd

LH/SAE FWD/SAE RH/SAE

9G 5G 10G

11G

6G

12G

LH/LU

FWD/LU

RH/LU

DOWN

+

0CONTROL

OR

T

2s

AND


LANDING GEAR DISTRIBUTION UNIT

(16G)

Extension

Retraction(15G)

Ground safety

ASU10 α

2

TEST

NORM.

EMERG.

EMERG.

ASU10 α 2

TEST

NORM.

EMERG.

EMERG.

ASU11α 2

10 α 2 ASU

13G

7G

14G

LH/LD

FWD/LD

RH/LD

DOWN

+

0

OR

T

2s

AND


LANDING GEAR

DISTRIBUTION UNIT (16G)

Extension

Retraction15G

UP

3α

3α

UP

CONTROL




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11.15

The electrical supply in emergency mode is doubled from 3 Alpha, 5 Alpha distribution panels and 37 Alpha diodes box.

The switch is set to "EMERG." position on the overhead panel, the pump control relay 19G (2) its contact in working

position. The "EMERG." switch (1) position supplies the A.S.U. 10 Alpha2 (3) logic isolating the normal extention

circuit.

The 19G relay (2) being supplied, the electrical pump (4) received a double supply from 5 Alpha and 3 Alpha distribution

panels. At the end of extension, the pressure increases in the emergency circuit, when this one reaches 95 bars. "L/

G PUMP" is displayed on the CAD, informing the pilot to set the 3 position switch (1) in "NORM" position.

If a failure occurs in the L/G extension system ( hydraulic or electrical failure) it is possible to extend the L/G in

emergency mode.

From the retracted L/G position, hydraulic pressure has to be delivered to the extension actuator. This pressure will besupplied by the emergency pump.

D7

E2

D3

D2

D8

DIODES

BOX

EMERGENCYEXTENSION

5α

Normal

EXT / RETRACT circuit

19G

5α

3α

37Alpha

TEST

NORMAL

EMERG

ASU

10 Alpha2

CAD

11.7.3.4 L/G EMERGENCY EXENSION CONTROL SYSTEM OPERATION

11.7.3 L/G NORMAL RETRACTION/EXTENSION CONTROL SYSTEM OPERATION (Cont'd)

1

4

3

2LG.PUMP




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11.16

11.7.4.2 L/G MANEUVER INDICATION

Whatever the selected mode (Normal/Emergency) the amber light maneuver indicates that the L/G is in motion. The

amber light "ON" indicates then the L/G is in motion. The "ground" of this indicator light comes from one actuator

microswitch position : locked down and locked up. This indicator light amber will remain "ON" as long as the L/G will be

not locked down or locked up.

11.7.4.3 L/G NOT EXTENDED INDICATION (ALARM)

The 14 Alpha (1) and the 15 Alpha (2) alarm panels receive a double supply 1+2 from the 36 Alpha (3) fuses box. This

control logic (Alarm) receives also a double supply from 3 Alpha (4) et 5 Alpha (5). L/G red indicator light flashing,indicates than at least one lock down actuator microswitch is not activated and the helo speed is below 55 KTS. The

analyse and process of this information is performed by the A.S.U. 11Alpha2 which provides a ground to the L/G

indicator light with a 2 Hz frequency and an usual warning.

11.7.4.1 L/G EXTENDED-LOCKED INDICATION

The L/G control panel 2G (1) receives a double supply from the fuses box 36 Alpha (2). The green arrows "ON" indicate

the extended and locked down positive of the L/G. The "ground" of these indication lights are supplied by actuators

microswiches locked down 14G (RH), 7G (FWD) and 13G (LH).

1

11.7.4 L/G INDICATING SYSTEM

2

3

1

2

5

4

RH/LU

FWD/LU

LH/LU

RH/LD

FWD/LD

LH/LD

11G

6G

12G

11α 2 ASU

13G

7G

14G

OR

AND

36 α

day/night1

day/night2

test (0v)

day/night 1+2

FUSES BOX

Up-locked

Down-

locked

15αααααCopilot

14αααααPilot

Aural

warning F=1,67Hz

5 α

3α

AS

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11.17

11.7.4.5 FLIGHT/GROUND LOGIC

General

The logic circuit clearly determine the aircraft configuration : Flight or Ground. It also allows or inhibits operation of

different aircraft systems (Autopilot, armement systems....). The Flight/Ground logic works with the L/G but also with

different aircraft systems requiring a high reliability.

Operation

The information detection is doubled. It's archieved by the LH and RH L/G with the microswitches 9G (1) and 10G (2).

From the fuses box 36 Alpha (3), a 28V 1+2 goes to the A.S.U. 11 Alpha2 (4) through the 10G (2) microswitch. Through

the 9G microswitch a ground will be sent (or not) to the A.S.U. 11 Alpha2 (4).

One pulse on the caption light L/G inhibits the aural warning (RST). This aknowledgement will remain in memory as

long as the helo airspeed will stay below 55 Kts. As soon as the speed will exceed 55 Kts, the acknowledgement will

be erased and the aural warning will be available as well.

11.7.4.4 RESETTING

56

78

12

3

56

78

D

C

D

D

C

C

12

4

1011

12

13

1415

1617

1716

14

1312

1110

15

A1

B7

B8

E

F

E

FLIGHT

GROUND

FLIGHT

D

11 Alpha 2

36 Alpha

15N

9G

10GFUSES

LH L/G STRUTASSEMBLY

RH L/G STRUT

ASSEMBLY

11.7.4 L/G INDICATING SYSTEM (Cont'd)

D




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1

11.8 POWER-ASSISTED BRAKES

11.8.1 SYSTEM DESCRIPTION & SPECIFICATIONS

The power braking system provides a braking pressure of 60 bars in response to a 430 bars input pressure.

The system is supplied by the auxiliary hydraulic system and includes the following components :- a parking brake control (1),

- 4 brake control transmitters (4) mounted on the pilot's and copilot's brake pedals,

- a braking distributor valve (3),

- an oléopneumatic accumulator (2) used to supply the parking brake,

- a cockpit floor-mounted pressure gauge (5) indicating the accumulator pressure.

3

24

5

11a-01_18

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