Extra 500. Maintenance Manual (2012) - page 11
26
Perform Leakage and Accumulator Function Test (see below).
27
Perform further tests or Gear Down Procedure and return aircraft to normal
observing respective procedures and warnings.
Wheels Up Landing Test
It is assumed aircraft is on jacks, the gear is up, BATT and/or EXT PWR switch
is ON, and GEAR-CTRL circuit breaker is in. Perform Gear Up Procedure if
applicable.
Make sure, that neither a person nor any object is located in the landing
DANGER
gear travel area.
1
Shut OFF BATT and EXT PWR switch.
2
Check gear position. The undercarriage must remain in retracted position.
3
Perform Gear Down Cycle Test Procedure or Gear Down Procedure and
return aircraft to normal observing respective procedures and warnings.
Gear Down Cycle Test
It is assumed aircraft is on jacks, the gear is up, BATT and/or EXT PWR switch
is ON, and GEAR-CTRL circuit breaker is in. Perform Gear Up Procedure if
applicable.
1
Measure gear down cycle with a stop watch.
Make sure, that neither a person nor any object is located in the landing
DANGER
gear travel area.
2
Pull and move LANDING GEAR switch DN.
3
Check gear extending and opening of all doors.
4
Check if the following lights illuminate during gear transition:
The red GEAR WARN annunciator light
The yellow HYDRAULIC PUMP annunciator light
5
After landing gear is down and locked check if performance time for a
complete gear down cycle is between 11 and 15 seconds (LH and RH gears
must not extend simultaneously).
6
Check if upper doors are closed.
7
Check if the red GEAR WARN and HYDRAULIC PUMP lights extinguish.
8
Check the three green lights for nose gear, LH and RH gear illuminating.
9
Return aircraft to normal observing respective procedures and warnings.
Gear Up Cycle Test With Rudder Full Left/Full Right
1
Lift the aircraft on jacks (see Chapter 07-10-00).
Upper landing gear doors will close immediately, when BATT or EXT PWR
DANGER
switch is turned to ON and GEAR-CTRL circuit breaker is in. Make sure,
that neither a person nor any object is located in the upper landing gear
doors travel area.
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2
Turn BATT and EXT PWR switch ON (left side panel, toggle switch).
3
Push circuit breaker GEAR-CTRL in (left side panel).
4
Apply full left rudder pedal control input.
Make sure, that neither a person nor any object is located in the landing
DANGER
gear travel area.
5
Pull and move LANDING GEAR switch UP.
6
Check if nose gear retracts without jamming in the nose wheel bay.
7
Perform Gear Down Procedure.
8
Apply full right rudder pedal control input.
Make sure, that neither a person nor any object is located in the landing
DANGER
gear travel area.
9
Pull and move LANDING GEAR switch UP.
10
Check if nose gear retracts without jamming in the nose wheel bay.
11
Perform further tests or Gear Down Procedure and return aircraft to normal
observing respective procedures and warnings.
Leakage and Accumulator Function Test
After two accumulator recharge cycles, the time before the third and the
following recharging actions has to be at least 2 minutes. Recharging action
can be heard as a short operation of the hydraulic power pack and is indicated
by the HYDRAULIC PUMP annuciator light.
32 Page 13
32-10-00
MAIN GEAR AND DOORS
32-10-10
Main Gear Strut Assembly
Description
The main gear has two hydraulically actuated main gear strut assemblies with
the following components (refer to Figure 32-1):
•
Undercarriage leg
•
Drag brace (upper and lower part)
•
Parallel strut
•
Upper guide strut
•
Lower guide strut
•
Axle bar
•
Shock absorber
The main gear bolt attaches the steel designed main gear strut assembly to the
main gear attachment frame.
The parallel strut, the upper and lower guide struts and the axle bar shape a
parallelogram (parallel guide strut construction).
The drag brace locks the extended main gear strut. The upper and lower part
are kept in overcenter position and fix the parallel strut in vertical.
The bearings above and below the parallel strut are the axle for the upper and
lower guide struts. The vertical movement of the guide struts is absorbed by the
shock absorber, which is attached between them.
The axle bar carries the main wheel and is attached to the upper and lower
guide struts by bearings.
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Figure 32-1
LH Main Gear Strut Assembly
32 Page 15
Removal
Detail Steps/Work Items
Key Items
1
Lift the aircraft on jacks
Chapter 07-10
2
Remove aft keel beam access panel
Refer to Chapter 51-00-01
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
3
Remove the bolt from the push pull rod
upper door
4
Lift the upper door and fasten by means of a
tape
5
Remove the clevis pin from the hinge joint
lower door
6
Remove the bolt between the torque link rod
and the main gear strut assembly
7
Remove the bolt between the short actuator
main gear and the main gear strut assembly
8
Unlock the mechanism of the interlocking
Apply shop air momentarily
actuator.
on the rod side fitting of the
interlocking actuator.
9
Remove the bolt between the interlocking
actuator and the main gear strut assembly.
Brake fluid can cause disease!
WARNING
Do not allow brake fluid to come in contact with your skin.
Brake fluid can damage paint and other material!
CAUTION
Clean up immediately spilt brake fluid
10
Remove the brake
Chapter 32-40-03
11
Disconnect reusable fitting of the brake
hose.
12
Remove brake line from main gear strut
13
Remove the main wheel
Chapter 32-40-01
14
Remove the limit switch
Chapter 32-60-01
15
Cut off the safety wires on both main gear
bolt nuts
16
Remove the lower nut completely from the
Hold the main gear strut until
thread.
completely removed.
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Detail Steps/Work Items
Key Items
17
Remove the upper nut.
While pulling the main gear
bolt with an extracting tool
(refer to Chapter 01-00-02)
18
Remove the main gear bolt and the lower
nut from the main gear attachment frame
19
Remove the assembled main gear
20
Remove the collar bushings in the main gear
strut assembly
Installation
1
Lubricate the fitting surface and thread of
Use only MILG81322D
the main gear bolt before installation
Grease
2
Install in reverse sequence of removal
Use new stop nuts and new
brake line with crimped
fitting on inboard side.
3
Bleed the brake system
Refer to Chapter 12-10-07
Disassembly/Assembly
Detail Steps/Work Items
Key Items
1
The track rods have to be removed
Chapter 32-30-40
False reassembled bolted connections can damage the gear struts and
CAUTION
doors.
Before removal of bolts and nuts, notice their position. It can be
different from the respective figure for geometric reasons.
2
Remove the bolts, stop nuts and washers
from the undercarriage leg
3
Remove the undercarriage leg from the
assembled strut structure
4
Remove the bolts, stop nuts and washers
from the upper part of the drag brace
5
Remove the upper part of the drag brace
from the assembled strut structure
6
Remove the collar bushings in the upper
part of the drag brace
7
Remove the bolts, stop nuts and washers
from the lower part of the drag brace.
8
Remove the lower part of the drag brace and
the parallel strut from the assembled strut
structure
32 Page 17
Detail Steps/Work Items
Key Items
9
Remove the collar bushings and shims in the
parallel strut
Tensioned construction due to nitrogen inflation damages hands and
WARNING
limbs!
The shock absorber is under high pressure (827 psi/57 bar)!
10
Relieve nitrogen pressure.
11
Remove the bolts, stop nuts and shims
between the shock absorber and the upper
and lower guide strut
12
Remove the shock absorber from the upper
and lower guide strut
13
Remove the bolt, stop nut and washer
between the upper guide strut and axle bar
14
Remove the upper guide strut from the axle
bar
15
Remove bolts, stop nuts and washers
between the lower guide strut and axle bar
16
Remove the lower guide strut from the axle
bar
17
Remove the collar bushings in the axle bar
18
Install in reverse sequence of removal
Use new stop nuts.
19
Check the toe-in whenever any part of the
main gear strut has been changed
Page 18 32
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32-10-11
Parallel Strut
Description
The steel designed parallel strut has the following components (refer to Figure
32-2):
Upper and lower T-strut
Rotary bushing with guide brackets
Jam nut with set screw
Adjusting nut with set screw
Inner and outer joint
Collar bushings in the rotary bushing
Collar bushings in the joints
Grease nipples
Attaching parts like bolts, stop nuts and washers
The parallel strut is steel designed. It is linked with the under-carriage leg, the
lower part of the drag brace and the upper and lower guide strut by the bearings
in the upper and lower T-strut.
When the landing gear is extended, the parallel strut is vertically fixed by the
undercarriage leg and the upper and lower part of the drag brace.
The upper T-strut is threaded and carries the adjusting nut and the jam nut,
which are for adjusting to avoid any vertical play.
The components with collar bushings inside like the axle guide bracket and the
upper and lower T-strut are equipped with grease nipples.
32 Page 19
Grease nipple
Upper T-strut
Set screw
Set screw
Jam nut
Upper guide bracket
Adjusting nut
Grease nipple
Collar bushing
Outer joint
Grease nipple
Inner joint
Rotary bushing
Collar bushing
Grease nipple
Lower guide bracket
Lower T-strut
Grease nipple
Figure 32-2
Parallel Strut
Removal/Installation
For removal of the parallel strut from the main gear strut assembly perform as
described in step 1 to 3 and 7 to 9 (refer to Subject 32-10-10 Main Gear Strut
Disassembly).
Disassembly/Assembly
Detail Steps/Work Items
Key Items
1
Remove the lower T-strut from upper T-
Turn lower T-strut
strut with rotary bushing.
counterclockwise
2
Remove the rotary bushing with its collar
bushings.
3
Loosen the jam nut and adjusting nut set
screws.
4
Loosen the jam nut from the adjusting nut
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Detail Steps/Work Items
Key Items
5
Remove the adjusting nut.
6
Remove the jam nut.
7
Remove the bolts, stop nuts and washers
from the inner and outer joint.
8
Remove the inner and outer joint.
9
Remove the joint collar bushings.
10
Install in reverse sequence of removal
Use new stop nuts
Adjustment of Vertical Play
Detail Steps/Work Items
Key Items
NOTE
This procedure does not require jacking the aircraft
1
Loosen the jam nut and adjusting nut set
screws.
2
Loosen the jam nut.
3
Tighten the collar bushings to the rotary
As long as any clearance
bushing by clockwise turning the adjusting
occurs
nut.
4
Tighten the adjusting nut set screw.
5
Counter the adjusting nut by the jam nut.
6
Tighten the jam nut set screw.
NOTE
Replace the collar bushings when their collar thickness is less then 3/64"
(1 mm)
32-10-12
Axle Bar
Description
The steel designed axle bar has the following components (see Figure 32-3):
Upper and lower T-strut
Rotary bushing with axle and axle guide bracket
Joint
Collar bushings in the joint
Grease nipples
Attaching parts like bolts, stop nuts and washers
The axle bar is linked with the upper and lower guide strut by the bearings in
the upper and lower T-strut.
32 Page 21
The axle carries the main wheel.
The rotary bushing and the upper and lower T-strut are equipped with grease
nipples.
Upper T-strut
Grease nipple
Rotary bushing
Axle guide bracket
Collar bushing
Grease nipple
Joint
Collar bushing
Grease nipple
Lower T-strut
Figure 32-3
Axle Bar
Removal/Installation
For removal of the axle bar from the main gear strut assembly follow step 1
and 13 to 17 (refer to Subject 32-10-10 Main Gear Strut Disassembly)
Disassembly/Assembly
Detail Steps/Work Items
Key Items
1
Remove the upper T-strut from lower T-
strut and the rotary bushing
2
Remove the collar bushing in rotary bushing
3
Remove the bolts, stop nuts and washers
from joint
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Detail Steps/Work Items
Key Items
4
Remove the joint
5
Remove the collar bushing in the joint
6
Install in reverse sequence of removal
Use new stop nuts
Adjustment of Vertical Play
For disassembly follow step
12 to
16
(Subject
32-10-10 Main Gear
Disassembly)
Detail Steps/Work Items
Key Items
1
The axle bar has to be removed
Follow step 1 and 13 to 17
(32-10-10 Main Gear Strut
Disassembly)
2
Tighten the collar bushings in the rotary
As long as any clearance
bushing by turning the upper T-strut (full
occurs
turns only) against the lower T-strut
clockwise.
NOTE
Replace the collar bushings when their collar thickness is less then
3/64"/ 1 mm
32-10-13
Shock Absorber
Description
The steel designed shock absorber has the following components (refer to
Figure 32-4):
Outer cylinder
Inner cylinder
Slide bearing
Piston
Throttle with disk and support
Seals like O-rings and scraper ring
Valves
Hinge bearings
Attaching parts like back up rings, safety pin and locking ring
The shock absorber is connected to the upper and lower guide strut by bolts.
The shock absorber is designed as oil/nitrogen filled cylinder. The lower outer
cylinder is filled with hydraulic oil; the upper inner cylinder is nitrogen
inflated. The piston in the upper inner cylinder separates the hydraulic oil from
32 Page 23
nitrogen inflation. The grounded and hardened surfaces of the inner cylinder
and the piston are sealed by O-rings.
Hinge bearing
Valve
Outer cylinder
Throttle with disk and support
Piston
Scraper ring
O-ring
Locking wire
Slide bearing
Inner cylinder
Valve
Hinge bearing
Figure 32-4
Shock absorber
Removal/Installation
For removal of the shock absorber from the main gear strut assembly follow
step 10 to 12 (refer to Subject 32-10-10 Main Gear Strut Disassembly)
Disassembly/Assembly
Detail Steps/Work Items
Key Items
High-pressure oil-jet damages eyes and limbs!
WARNING
The shock absorber is under high pressure (827 psi/57 bar)
1
Release nitrogen pressure and drain the
Refer to Chapter 12-10-09
hydraulic fluid completely in a sump
2
Remove the locking wire from the outer
cylinder.
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Detail Steps/Work Items
Key Items
3
Remove the outer cylinder from the slide
bearing
4
Remove the O-ring and the back up-ring
from the outer cylinder
5
Remove the safety pin from the slide
bearing and the inner cylinder
6
Remove the support throttle, the disc and the
throttle from inner cylinder
7
Remove the inner cylinder from the slide
bearing
8
Remove the O-ring, the back up-rings and
the scraper ring from the slide bearing
9
Push the piston out of the inner cylinder
10
Remove the O-ring and the back up-rings
11
Install in reverse sequence of removal
Use new stop nuts
12
Seal locking wire.
Elastosil E14, GE RTV 159
or equivalent
13
Refill hydraulic fluid into the cylinder and
Refer to Chapter 12-10-09
apply nitrogen pressure.
14
Check the wheel track
32-10-20
Main Gear Doors
Description
The carbon fiber designed upper and lower doors fair the retracted main gears.
The hinges are integrated in the door lamination.
The upper doors are connected to the fuselage by two hinges each. Hydraulic
actuators drive the upper doors by levers with push pull rod.
The lower doors are connected to the fuselage by three hinges each. An
hydraulic actuator drives both lower doors by levers with cardan hinge joint.
32 Page 25
32-10-21
Upper Doors
Removal/Installation
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
1
Remove the bolt between the upper door
and the push pull rod.
2
Remove the bolts from both hinges.
Hold the door
3
Remove the upper door.
4
Install in reverse sequence of removal.
Use new stop nuts
Door Actuation Length Adjustment
The outer push-pull rods for the upper doors are attached to the resp. door front
section. For adjusting LH resp. RH push-pull rod, loosen upper and lower
locknut and turn threaded rod. Re-tighten and torque locknuts with
4 Nm ± 0.2 Nm (35.4 inch.lbf. ± 1.8 inch.lbf.). Perform gear up procedure
(refer to Subject 32-31-01) and check that doors are closing correctly. Repeat
adjustment as necessary.
32-10-22
Lower Doors
Removal/Installation
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
1
Remove the clevis pin from hinge joint of
the lower door
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Detail Steps/Work Items
Key Items
2
Remove the bolts, stop nuts and washers
Hold the door
from the hinge
3
Remove the lower door
4
Install in reverse sequence of removal
Use new stop nuts
Door Actuation Length Adjustment
The inner push-pull rods for the lower doors are located about half door length
below the wheel well. For adjusting LH resp. RH push-pull rod, loosen upper
stop nut LN 9348-06 and turn threaded rod. Re-tighten and torque upper stop
nuts with 6.5 Nm ± 0.3 Nm (57.5 inch.lbf. ± 2.5 inch.lbf.).
Detach the upper doors to prevent them from damage during the
CAUTION
following test in case the adjustment is not yet correct. Remove the bolt
from the push pull rod upper door. Lift upper door and fasten with tape.
Perform Gear Up Procedure (refer to Subject 32-00-00) and check that doors
are closing correctly. Repeat adjustment as necessary. Reattach upper doors.
NOTE
Do not re-tighten lower stop nuts, but leave nuts ¼ - turn unlocked. This
will allow threaded rods to turn in case both doors are not actuated evenly,
thus reducing tension in the actuation mechanism.
32 Page 27
32-20-00
NOSE GEAR AND DOORS
Description
Two trunnion bolts attach the nose gear oleo leg strut to the engine mounting.
The nose strut, using an oleo-hydraulic shock absorber, is operated by a
hydraulic actuator and retracts aft in the nose gear compartment. In case of
hydraulic system failure, the nose gear extends by two gas pressurized springs
against air loads. A ground safety switch, located at the drag brace of the nose
gear, prevents accidental nose gear retraction during ground operation.
In flight the nose doors fair the nose gear strut.
32-20-10
Nose Gear Strut Assembly
Description
The nose gear consists of the following parts (see Figure 32-5)
• Trunnion
• Drag brace
• Steering arm assembly
• Oleo leg (upper and lower strut)
• Torque link
• Shimmy damper assembly
The trunnion assembly carries the drag brace and the steering arm assembly.
The support tubes and tubes for the RH and LH pivot bearings are welded to
the trunnion.
The upper strut of the Oleo leg fits inside the trunnion.
The torque link is bolted to the upper strut and the lower strut of the Oleo leg.
It prevents the lower strut from turning inside the upper strut.
The drag brace is attached to the trunnion and the engine mounting. It locks
the extended Oleo leg. In case of hydraulic system failure, the drag brace is
locked in extended position by two gas pressurized springs, which are pivoted
at the upper part of the drag brace.
The shimmy damper assembly dampens lateral moving of the nose gear while
taxiing. It is attached to the trunnion.
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Side View
Gas pressurized springs
Shimmy damper
Hydraulic actuator
Trunnion
Nose gear extended
Upper strut
switch
Oleo leg
Ground safety switches
Drag brace
Torque link
(upper and lower part)
Lower strut
Wheel
Figure 32-5
Nose Gear
32 Page 29
32-20-20
Nose Gear Doors
Description
The carbon fibre nose gear doors are attached to the fuselage by aft and
forward door hinges. The nose gear doors are operated by the nose gear door
actuation mechanism, which is linked to the trunnion (refer to Figure 32-6).
The actuation mechanism consists of the following parts:
•
Spring
•
Telescope guide rod
•
Push-pull rod (one each side)
•
Two-armed rocker lever incl. stop
The doors are closed in the last part of the nose gear retraction phase. Then the
telescope guide rod is fully extended and begins to drive the actuation
mechanism. The spring presses the rocker lever against the stop thus keeping
the actuation mechanism in the over-centered position and the doors open.
Door Actuation Length Adjustment
The push-pull rods for the nose gear doors are attached to the resp. door front
section. For adjusting LH resp. RH push-pull rod, loosen upper and lower
locknut and turn threaded rod. Re-tighten and torque locknuts with
4 Nm ± 0.2 Nm (35.4 inch.lbf. ± 1.8 inch.lbf.). Perform gear up procedure
(refer to Subject 32-31-01) and check that doors are closing correctly. Repeat
adjustment as necessary.
Page 30 32
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Figure 32-6
Nose Gear Doors Actuation Mechanism
32 Page 31
32-30-00
EXTENSION AND RETRACTION
Description
Refer to Figures 32-7 and 32-8. Extension and retraction of main gear and nose
gear is controlled by hydraulic actuators. The main landing gear doors are also
hydraulically actuated. Nose landing gear doors are mechanically linked to the
trunnion of the nose gear. The equipment for extension and retraction consists
of the following components:
1
Hydraulic system components with the items:
a
Power pack, consisting of:
Hydraulic pump with geared electric motor
By-pass valve
Strainer
Reservoir
b
Distributor block, consisting of:
3 directional valves
Pressure switch
Diaphragm pressure accumulator
2
Hydraulic actuators for gears and doors
4 Main gear actuators (1 short actuator and 1 interlocking actuator each side)
2 Actuators for upper doors
Actuator for lower doors
Nose gear actuator
3
Hydraulic lines
Part 1 Gear actuation
Part 2 Main gear lower and upper doors actuation
Part 3 Power supply
4
Torque link and track rods
5
Drive mechanism nose doors
The hydraulic power pack together with the distributor block provide the
landing gear system as well as the respective landing gear doors with a flow of
pressurized hydraulic fluid (operation-pressure 100-120 bar/1,450-1,740 PSI).
Hydraulic pressure is maintained throughout ground and flight operation as
long as the electric battery bus is powered. An external, adjustable pressure
switch, mounted to the distributor block, cuts off electric power as soon as
120 bar (1,740 PSI) are reached. The pressure switch will return power to the
hydraulic pump when pressure drops below below 100 ± 5 bar (1,450 ± 2.5
PSI). As an additional safety device the equipment chassis of the power pack
carries a pressure relief valve which will open the bypass above the pump once
the pressure would exceed 130 bar (1,885 PSI). The hydraulic power pack with
pump, strainer and reservoir as well as the distributor block with control valves
and pressure switch are built into the hydraulic power compartment in front of
the main gear attachment frame between the keelbeams.
Page 32 32
Page Date:
The hydraulic fluid level can be checked any time by means of an inspection
glass on the hydraulic power pack reservoir, visible behind an opening in the
keelbeam. It is accessible from the R/H main wheel bay. Just above the L/H
side of the inspection glass is the filling cap for the hydraulic fluid.
A small nitrogen diaphragm accumulator is used to eliminate the necessity of
frequent hydraulic pack activation due to small internal system leakage. This
accumulator is located underneath the passenger cabin floor within the
pressurized (and heated) vessel to avoid embrittlement of the diaphragm during
high altitude low temperature operation.
A yellow HYDRAULIC PUMP caution light is included into the annunciator
panel, which indicates hydraulic pump activity and normally shall illuminate
for not more than 2 or 3 seconds after periods of several minutes of rest, or
during landing gear operation. (See Subject 32-00-00 Leaks and Accumulator
Function Test.) If longer constant pump action or shorter periods of rest are
observed, refer to Troubleshooting Paragraph in this Chapter. Prolonged pump
operation for more than 2 minutes will cause pump or electric motor to
overheat.
The distributor block is equipped with three solenoid directional control valves
and the pressure switch. The hydraulic fluid is directed by the control valves;
these are spring loaded and will automatically switch into the gear down
position once electric power is lost. However, when selecting LANDING GEAR
DN, de-energizing the main gear control valve is slightly time delayed by
means of a capacitor. This allows the main gear doors to open first (to prevent
contact to the main landing gear strut).
The hydraulic system is separated in three circuits to actuate the respective
devices:
1
Extension/retraction of main gear and nose gear
2
Opening/closing of the lower main gear doors
3
Opening/closing of the upper main gear doors
The main and nose gear struts and doors are separately actuated by hydraulic
cylinders. Two hydraulic actuators drive each main gear strut. One of the
cylinders (the interlocking actuator) is designed to carry the breaking loads and
has a mechanical locking mechanism.
The torque link rod tows and unlocks the drag brace when the actuators start
retracting. It shortens the main gear strut while retracting to fit it into the wheel
bay. The track rods turn and push the coupled axle bar together with its wheel
forward to drive it into the wheel bay.
The nose gear strut is driven by one hydraulic actuator. For emergency
extending the nose gear strut is equipped with two gas pressurized springs.
They push the nose gear out in case of hydraulic system failure. The nose gear
has a positive downlock by an overcenter device (drag brace).
The upper main gear doors are driven by a hydraulic actuator each. The lower
main gear doors are driven by one common hydraulic actuator. The nose gear
doors are positively guided by the nose gear strut.
All parts of the hydraulic system are hydraulically connected by lines. They
consist of aluminum tubes and braided reinforced Teflon hoses. The actuators
are connected by the Teflon hoses.
Page Date:9. August 2013
32 Page 33
GEAR WARN MUTE
L/N/R DOWN
Three Green Lights
GEAR AUX 1 Circuit Breaker
Gear Warning
Circuit Board
GEAR AUX 2 Circuit Breaker
Gear Warning Horn
GEAR CTRL Circuit Breaker
HYDR Circuit Breaker
Annunciator Panel
Landing Gear Switch
Ground Safety Switch
Diaphragm
Accumulator
Hydraulic Pump
(driven by electric motor)
Reservoir
Limit
Valve
Switch(es)
Main Gear Lower Doors
Limit
Valve
Switch(es)
Main Gear Upper Doors
Limit
Valve
Switch(es)
Main Gear Struts and
Nose Gear Strut & Doors
Legend:
Electrical Wiring
Diode
Hydraulic Lines
Capacitor
Hydraulic Cylinder(s)
Figure 32-7
Landing Gear Schematic
Page 34 32
Page Date:
Figure 32-8
Main Gear Actuators
32 Page 35
32-30-10
Hydraulic System
Bleeding
This procedure describes bleeding the hydraulic system by operating the
landing gear and then refilling hydraulic fluid. Follow this procedure when
smaller works with little loss of hydraulic fluid have been performed on the
hydraulic system such as removal and installation procedures of single
components. Generally, when hydraulic lines have been plugged during these
procedures and the respective components have been pre-filled with hydraulic
fluid before reinstallation this bleeding procedure shall be sufficient.
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
Hydraulic fluid can cause disease!
WARNING
Do not allow hydraulic fluid to come in contact with your skin.
Hydraulic fluid can damage paint and other material!
CAUTION
Clean up immediately spilt hydraulic fluid.
1
Lift the aircraft on jacks.
Chapter 07-10-00
Upper landing gear doors will close immediately, when BATT or
DANGER
EXTR PWR switch is turned to ON and GEAR-CTRL circuit breaker is in.
Make sure, that neither a person nor any object is located in the upper
landing gear doors travel area.
2
Turn BATT and EXT PWR switch ON.
3
Push circuit breaker GEAR-CTRL in.
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Make sure, that neither a person nor any object is located in the landing
gear travel area.
4
Operate the landing gear:
1 Retraction cycle
1 Extension cycle
5
Turn BATT and EXT PWR switch OFF.
6
Pull circuit breaker GEAR-CTRL.
7
Check hydraulic fluid level; if necessary,
Use MILH5606 Hydraulic
refill hydraulic fluid until the oil level just
Fluid
covers the center line of the gauge glass.
Page 36 32
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Detail Steps/Work Items
Key Items
NOTE
Pay attention to noise in the restrictor nozzles to localize trapped air in
the system.
Drive maximum 5 cycles; then allow power pack to cool down.
CAUTION
8
Repeat steps 2 to 7, until correct fluid level
remains constant.
9
Remove the tape from RH upper door and
re-install the bolt to the push pull rod.
Hydraulic Fluid Change
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
Hydraulic fluid can cause disease!
WARNING
Do not allow hydraulic fluid to come in contact with your skin.
Hydraulic fluid can damage paint and other material!
CAUTION
Clean up immediately spilt hydraulic fluid.
1
Lift the aircraft on jacks
Chapter 07-10-00
2
Remove the hydraulic power pack
Refer to Chapter 32-30-11
Removal/Installation
3
Clean hydraulic power pack and filter.
Refer to Chapter 32-30-11
Cleaning
4
Remove the oil vent plug from the
reservoir.
5
Refill hydraulic fluid through vent plug
Use MILH5606 Hydraulic
opening of the reservoir up to maximum
Fluid
level.
6
Plug a temporary breather hose (diameter 6
mm/1/4 inch) with fitting into the vent plug
opening.
7
Re-install the hydraulic power pack. Let
Refer to Chapter 32-30-11
upper RH door in lifted position.
Removal/Installation omitting
steps 2 and 3.
32 Page 37
Detail Steps/Work Items
Key Items
8
Lead breather hose through free opening in
keel beam to RH access compartment in
front of main wheel bay
During gear retraction, high pressure oil jet from the return line
WARNING
damages eyes and limbs!
Cover return line in the sump with mesh gate to retain spilling fluid.
Upper landing gear doors will close immediately, when BATT or
DANGER
EXT PWR switch is turned to ON and GEAR-CTRL circuit breaker is in.
Make sure, that neither a person nor any object is located in the upper
landing gear doors travel area.
8
Turn BATT and EXT PWR switch ON (left side panel, toggle switch)
9
Push circuit breaker GEAR-CTRL in (left side panel)
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Make sure, that neither a person nor any object is located in the upper
landing gear doors travel area.
10
Pull and move LANDING GEAR switch UP
(left main panel, below RH side of control
yoke)
NOTE
Assure adequate fluid volume to avoid trapped air in the system
11
Refill reservoir through breather hose with
read out 1100 cm (67 cu in)
hydraulic fluid up to maximum level.
or refill until fluid runs out
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Make sure, that neither a person nor any object is located in the upper
landing gear doors travel area.
12
Pull and move LANDING GEAR switch DN.
13
Turn BATT and EXT PWR switch OFF.
When landing gear is down
and locked.
14
Pull circuit breaker GEAR-CTRL.
15
Remove breather hose.
16
Screw the oil vent plug to the reservoir.
17
Remove the tape from RH upper door and
re-install the bolt to the push pull rod
18
Return aircraft to normal observing
respective procedures and warnings.
Page 38 32
Page Date:
32-30-11
Hydraulic Power Pack
Removal/Installation
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
1
Ensure BATT switch is OFF and no external
power connected.
2
Remove the aft keel beam access panel.
Refer to Chapter 51-00-01
3
Remove the bolt from the push pull rod
upper door RH.
4
Lift the upper door RH and fasten it by
means of a tape.
5
Disconnect the electric power supply from
the hydraulic power pack.
Hydraulic fluid can cause disease!
WARNING
Do not allow hydraulic fluid to come in contact with your skin.
Hydraulic fluid can damage paint and other material!
CAUTION
Clean up immediately spilt hydraulic fluid
6
Disconnect the hydraulic lines from the inlet
Refer to Chapter 32-30-30
and outlet fitting of the hydraulic power
pack.
7
Install blind plugs to the disconnected lines
to avoid trapped air in the system.
NOTE
For identification, tag each hydraulic line. The line connecting the sump
to the hydraulic pump is identified as return line, the line leading
directly to the control valve is the pressure line.
8
Remove 2 attachment bolts of the power
Hold unit
pack.
9
Drain the hydraulic fluid
10
Install in reverse sequence of removal
11
Perform Bleeding procedure.
Refer to Subject 32-30-10
32 Page 39
Cleaning
This procedure describes cleaning the interior of the hydraulic power pack and
the incorporated suction filter. It is assumed that the hydraulic power pack is
removed from aircraft.
Detail Steps/Work Items
Key Items
1
Place the power pack in upright position.
Electric motor up
2
Remove the 4 bolts from the reservoir sump
Catch spilling hydraulic fluid
3
Remove the hydraulic power pack from the
reservoir.
4
Pour hydraulic fluid of the reservoir
completely in an external suitable container.
5
Clean the inside of the reservoir sump from
By means of lint-free rags
sludge
6
Pull off the suction filter from the suction
line
7
Dry and clean the suction filter carefully
By means of lint-free rags
8
Place the hydraulic power pack to the
Check the sealing ring for
reservoir.
proper arrangement
9
Reinstall the 4 reservoir attaching bolts.
10
Refill hydraulic fluid.
Use MILH5606 Hydraulic
Fluid 1100 cm (67 cu in)
32-30-12
Distributor Block
Removal/Installation
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
1
Ensure BATT switch is OFF and no external
power connected.
2
Remove the aft keel beam access panel.
Refer to Chapter 51-00-01
3
Remove the bolts from the push pull rods of
the upper doors.
Page 40 32
Page Date:
Detail Steps/Work Items
Key Items
4
Lift the upper doors and fasten them by
means of a tape.
5
Disconnect the electrical plug of the control
cables from the directional valves and from
the pressure switch.
Hydraulic fluid can cause disease!
WARNING
Do not allow hydraulic fluid to come in contact with your skin.
Hydraulic fluid can damage paint and other material!
CAUTION
Clean up immediately spilt hydraulic fluid.
6
Remove the hydraulic lines from the fittings
Chapter 32-30-30
of the distributor block.
7
Install blind plugs to the disconnected lines
to avoid trapped air in the system.
8
Remove the bolts, washers and spacer
Hold the unit
sleeves from the distributor block.
9
Remove the distributor block-
10
Drain the hydraulic fluid of the distributor
block in a sump.
11
Cover all hydraulic inlets and outlets by
plastic caps.
12
Install in reverse sequence of removal
13
Perform Bleeding procedure.
Refer to Subject 32-30-10
Disassembly/Assembly
Detail Steps/Work Items
Key Items
1
Cut off the safety wire on the top side of the
directional valves.
2
Remove the Allen bolts and lock washers
from the directional valves.
3
Remove the directional valves from the
Valve solenoids are “spot”
distributor block.
connected to each other with
silicone.
Catch the O-ring from the
directional valves
4
Unscrew and remove the pressure switch
Catch the O-ring from the
from the distributor block.
pressure switch
5
Remove the nipples and elbows from the
distributor block.
32 Page 41
Detail Steps/Work Items
Key Items
NOTE
Sign the elbows with a tag to ensure re-assembly at the original position
on the distributor block. The original position is required for the proper
fitting and mounting of the distributor block on its place between the
keel beams.
6
Install in reverse sequence of removal.
Lock up the Allen bolts of the
directional valves by safety
wire and “spot” fix solenoids
with Elastosil E14, GE RTV
159 or equivalent
32-30-20
Actuators
32-30-21
Main Gear Actuators
Each side of the main landing gear is driven by two hydraulic actuators (see
Figure 32-8):
• Short actuator
• Interlocking actuator
Removal/Installation
The following procedure applies for both actuators. However the interlocking
actuator has to be unlocked before removal as described in step 6.
Detail Steps/Work Items
Key Items
Landing gear extends and retracts under high pressure. Operation of
DANGER
the landing gear can cause death or injuries in its working area!
Before beginning any work in the landing gear working area, pull the
electric circuit breaker located on the left side panel and marked
GEAR-CTRL.
In case of intentional gear operation by switch or circuit breaker
handling make sure, that neither a person nor any object is located in
the landing gear travel area.
1
Lift the aircraft on jacks
Chapter 07-10-00
2
Remove the bolt from the push pull rod
upper doors.
3
Lift the upper doors and fasten them by
means of a tape.
Page 42 32
Page Date:
Detail Steps/Work Items
Key Items
Hydraulic fluid can cause disease!
WARNING
Do not allow hydraulic fluid to come in contact with your skin.
Hydraulic fluid can damage paint and other material!
CAUTION
Clean up immediately spilt hydraulic fluid.
4
Remove the hydraulic lines from the
Chapter 32-30-30
hydraulic actuator fittings.
5
Install blind plugs to the disconnected lines
to avoid trapped air in the system.
False reassembled bolted connections can damage the gear struts and
CAUTION
doors.
Before removal of bolts and nuts, notice their position.
6 (interlocking
Momentarily apply shop air to the fitting at
To release the down locked
actuator only)
the rod end side of the hydraulic cylinder.
position.
7
Remove the bolt, the stop nut and the
washers between the rod end of the
hydraulic actuator and the main gear strut
assembly.
8
Remove the bolt, the stop nut and the
Hold the hydraulic actuator
washers between the cylinder side of the
hydraulic actuator and the bracket on the
keel beam.
9
Remove the hydraulic actuator.
10
Measure the fully extended actuator length.
11
Install in reverse sequence of removal
Use new stop nuts
12
Check actuator for length.
Set the fully extended length
to the previously measured
length.
13
Perform Bleeding procedure.
Refer to Subject 32-30-10
32 Page 43