W DOC AIRBUS | AMM A320F

Repair of Hydraulic Tubes with CRYOFIT Couplings 3PHS111-XX


TASK 20-23-11-300-006-A
Repair of Hydraulic Tubes with CRYOFIT Couplings 3PHS111-XX


1. Reason for the Job
NOTE: This procedure is applicable to:
  • Titanium-alloy (Ti-3Al-2.5V) tubes ref. ABS5004, sizes -04 to -16
  • Corrosion-resistant steel (21-6-9) tubes ref. ASNA3288, sizes -04 to -24
  • Aluminum-alloy (6061-T6) tubes ref. ASNA3410 and DAN40, sizes -04 to -16 and -24.
NOTE: This repair procedure is not applicable to:
  • Hydraulic tubes in the engine area
  • Coiled tubes
  • Hydraulic tubes installed on the landing gear legs.
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
1
CLOTH-EMERY (GRADE 400)
No specific
AR
COUPLING INSTALLATION TOOL
No specific
AR
PAD - ABRASIVE
No specific
AR
STOPWATCH
 B. Consumable Materials
REFERENCE
DESIGNATION
(Material No.04CMA2)
Wash Primer_- - Structure
(Material No.04EAC2)
Primer Polyurethane Paint_- Corrosion Inhibiting Structure
(Material No.08BAA9)
Non Aqueous Cleaner-General - -
(Material No.10ABC1)
Surface Pretreatment-Light Alloys Chemical Conversion Yellow -
(Material No.14SBA1)
Textile-Lint free Cotton -
 C. Referenced Information
REFERENCE
DESIGNATION
TASK 12-12-29-611-001-A
Fill the Hydraulic Fluid Reservoir with a Hand Pump
TASK 12-12-29-611-002-A
Fill the Hydraulic Fluid Reservoir with a Hydraulic Service Cart
TASK 20-23-11-200-001-A
Permitted Damage and Defects on Hydraulic Tubing
TASK 20-23-11-917-003-A
Cutting and Deburring of Hydraulic Tubes
TASK 29-00-00-864-001-A
Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 29-00-00-870-001-A
Bleeding Procedure of the Green Hydraulic System Upstream of the Engine Pump
TASK 29-00-00-870-002-A
Bleeding Procedure of the Green Hydraulic System Upstream of the PTU
TASK 29-00-00-870-003-A
Bleeding Procedure of the Green Hydraulic System Downstream of the Engine Pump
TASK 29-00-00-870-004-A
Bleeding Procedure of the Yellow Hydraulic System Upstream of the Engine Pump
TASK 29-00-00-870-005-A
Bleeding Procedure of the Yellow Hydraulic System Upstream of the PTU
TASK 29-00-00-870-006-A
Bleeding Procedure of the Yellow Hydraulic System Upstream of the Yellow E-Pump
TASK 29-00-00-870-007-A
Bleeding Procedure of the Yellow Hydraulic System Downstream of the Engine Pump
TASK 29-00-00-870-008-A
Bleeding Procedure of the Blue Hydraulic System Upstream of the Blue E-Pump
TASK 29-00-00-870-009-A
Bleeding Procedure of the Blue Hydraulic System Downstream of the Blue E-Pump
TASK 29-00-00-910-002-A
Safety Procedures of the Hydraulic System
TASK 29-10-00-863-001-A
Pressurize the Green Hydraulic System with a Hydraulic Ground Power-Cart
TASK 29-10-00-863-002-A
Pressurize the Yellow Hydraulic System with a Hydraulic Ground Power-Cart
TASK 29-10-00-863-003-A
Pressurize the Blue Hydraulic System with a Hydraulic Ground Power-Cart
TASK 29-10-00-863-003-A-01
Pressurize the Blue Hydraulic System with the Blue Electric Pump
TASK 29-14-00-614-001-A
Depressurization of the Hydraulic Reservoirs
TASK 29-14-00-614-002-A
Pressurization of the Hydraulic Reservoirs through the Ground Connector
TASK 29-14-00-614-002-A-01
Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU)
TASK 29-23-00-863-001-A
Pressurize the Green Hydraulic System from the Yellow Hydraulic System through the PTU with the Electric Pump
TASK 29-23-00-863-002-A
Pressurize the Yellow Hydraulic System from the Green Hydraulic System through the PTU with the Ground Service Cart
TASK 32-42-00-870-001-A
Bleeding of the Normal Braking at the Brake Units
TASK 32-43-00-612-001-A
Filling and Bleeding of the Low Pressure Control System of the Alternate Braking
TASK 32-43-00-612-001-A-01
Filling and Bleeding of the Low Pressure Control System of the Alternate Braking using Green Reservoir fluid
TASK 32-43-00-870-002-A
Bleeding of the High Pressure Alternate Braking System
3. Job Set-up
Subtask 20-23-11-860-053-A
A. Safety Precautions
   (1) For installation of CRYOFIT couplings you must use small quantities of liquid nitrogen.
     (a) Liquid nitrogen is:
  • Very cold -196 deg.C (-320.80 deg.F)
  • Non-toxic
  • Non-corrosive
  • Non-flammable
  • A poor electrical conductor.
     (b) You must obey these precautions when you use CRYOFIT couplings and liquid nitrogen:
  • Keep the couplings and the liquid nitrogen in a correct container (work box)
  • Do the work in an area with a good flow of air
  • Prevent long contact with the skin
  • Wear gloves as shown in this procedure when you touch cold parts
  • Do not put gloved hands into liquid nitrogen
  • Wear safety glasses
  • Use correct tools.
     (c) If liquid nitrogen spills:
  • Stay clear of the spilled liquid. It will very rapidly evaporate
  • Immediately remove any clothing or shoes soaked with liquid nitrogen
  • Flush your skin with warm water and immediately get medical aid if the liquid nitrogen burns you
  • If the liquid nitrogen goes in your eyes, flush them with water and immediately get medical aid.
   (2) Obey the safety procedures of the hydraulic system (Ref. AMM TASK 29-00-00-910-002).
   (3) Make sure that the hydraulic reservoirs and the hydraulic systems are depressurized (Ref. AMM TASK 29-00-00-864-001) and (Ref. AMM TASK 29-14-00-614-001).
Subtask 20-23-11-917-072-A
B. Equipment
   (1) COUPLING INSTALLATION TOOL.
For installation of CRYOFIT couplings, you must use the tools below:
  • A work box to put the parts fully into liquid nitrogen.
  • A pair of gloves to touch the cold parts
  • A marking pen to make the installation marks on the tubes.
  • Tongs to remove the parts from the liquid nitrogen
  • Applicable tube chillers to make the tubes cold before the installation of the couplings
  • Applicable snap-on couplings or O-rings to stop the movement of the coupling (installation stop)
  • Applicable marking gages to make the installation marks
  • Applicable test couplings for the check of the tube joints
  • Applicable extended time tools to increase the recovery time of the coupling.
   (2) Coupling Assembly - 3PHS111-XX
     (a) Before you start the installation, make sure that you use the correct coupling assembly
Subtask 20-23-11-917-073-A
C. Installation Clearance
   (1) Installation package clearance.
     (a) You must have sufficient clearance to remove the installation package after the installation of the coupling.
   (2) Radial clearance.
     (a) The clearance around the CRYOFIT coupling installations must be sufficient for the removal of the installation package.
NOTE: If you use the extended time tool, the clearance must be greater because the extended time tool has a larger outside diameter. You can use a test coupling and an installation package or an extended time tool to do a check of the clearance.
   (3) Axial clearance.
The necessary axial clearance and length of straight tube (without deformation) will change with the coupling size and the installation technique used.
The length of tube engaged in each end of the coupling must be equal to half the length of the coupling.
To put the coupling in position, you can:
  • Move the tube axially (if possible)
  • Move the tube laterally (deflection).
     (a) Installation of the coupling by axial movement of the tube.
To do this procedure:
  • Axially pull one tube away from the other until you can put the coupling in position
  • Put the coupling in position on one tube
  • Engage the other tube in the coupling.
NOTE: For this procedure:
  • You must have a minimum length of straight tube (1/2 the coupling length for each tube end)
  • It must be possible to move the tube axially.
     (b) Installation of the coupling by lateral movement (deflection) of the tube
This is an alternative to the axial movement procedure.
To do this procedure:
  • Move the tube to one side
  • Put the coupling on the moved tube
  • Put the tube back in position
  • Engage the coupling on the other tube until the coupling is in the correct installation position.
NOTE: For this procedure:
  • Axial movement of the tube is not necessary
  • You must have a length of straight tube (without deformation) on one end equal to the full length of the coupling.
   (4) Tube bend location.
     (a) Tube bends prevent movement of the coupling. The coupling can be against a bend (or a bump) if you have sufficient clearance to install the coupling correctly.
   (5) Increase in assembly dimension (growth).
     (a) When a CRYOFIT coupling decreases (shrinks) in diameter, its length increases and moves the two tubes apart.
You must think about this when you make the decisions about the coupling installation procedure (tube lengths, bend locations, bumps).
     (b) Calculated increase in length (growth) after assembly.
Tube Size
Tube DIA in.
Tube DIA mm
Aluminum,titanium, stainless steel in. (mm)
-04
1/4
6.35
.016 (0.40)
-06
3/8
9.525
.020 (0.50)
-08
1/2
12.70
.026 (0.66)
-10
5/8
15.875
.034 (0.86)
-12
3/4
19.050
.037 (0.94)
-16
1
25.4
.040 (1.02)
-20
1-1/4
31.750
.045 (1.14)
-24
1-1/2
38.10
.059 (1.50)
4. Procedure
Subtask 20-23-11-917-074-A
A. Preparation
   (1) Put marks on the tube where you will cut the tube to remove the damaged part. When you put the marks on the tube, think about:
  • Access for the tube cutter and the CRYOFIT couplings
  • Where to release the tube. For installation of the coupling, a minimum of one tube end must be free to move
  • Possible future problems and a new routing of the tube (where permitted) to prevent chafing or contact with parts that move
  • Drainage of hydraulic fluid
  • Sufficient straight length of tube after removal of the damaged part
  • Minimum splice length
  • Assembly growth
  • Removal and replacement of paint or other protections on the tube adjacent to the repair.
   (2) If possible, drain the line near the location of the repair.
   (3) Tube cutting and deburring
  • Cut the tube and remove the damaged part (Ref. AMM TASK 20-23-11-917-003).
  • Make sure that the tube ends have no burrs (inner and outer side).
    Deburr if necessary.
   (4) If applicable, remove paint or other protection, with CLOTH-EMERY (GRADE 400), on one coupling length of the cut tube ends. Make sure that you do not scratch the tube when you remove the protection.
   (5) Cut, deburr and remove paint from all tubes you will use to replace the damaged part of tube: (Ref. AMM TASK 20-23-11-917-003).
   (6) Make sure that all the tube ends are in the correct condition and agree with the tube dimension specifications (Ref. AMM TASK 20-23-11-200-001).
   (7) Clean all the tube ends with Textile-Lint free Cotton - (Material No.14SBA1) and Non Aqueous Cleaner-General - - (Material No.08BAA9) .
NOTE: Make sure that the cleaning agent does not go in the tube.
Subtask 20-23-11-917-075-A
B. Coupling Installation
NOTE: To install all CRYOFIT couplings, you do these steps:
  • Attach one side of the tube joint
  • Move the other side
  • Slide the coupling over one of the tube ends
  • Align the tubes
  • Move the coupling back over the joint and allow it to recover.
   (1) Loosen the tube clamps on one side of the joint to permit the movement of one of the tubes. If possible, the other tube must stay attached.
NOTE: Make sure that:
  • Bulkhead fittings and reconnectable fittings on the same tube run (or on a branch run) are installed before you install the CRYOFIT coupling
  • Bulkhead fitting jam-nuts are torqued to the correct value
  • Reconnectable fittings are hand tight.
   (2) Do a check of all the joints with a test coupling.
     (a) With the applicable test coupling, do a check for burrs, tube alignment, tube gap and tube roundness.
NOTE: The coupling has a 0.03 in. (0.7620 mm) hole (window) in its center, which is the maximum permitted tube gap.
NOTE: The test coupling must move freely on the joint when the tubes are aligned. Do not try to force the tubes to align with the coupling because this will cause stress in the tubing system.
   (3) Mark the tubes.
     (a) Put the applicable marking gauge on each tube end. With the marking pen, color the rectangular box. These 0.03 in. (0.7620 mm) marks will be the installation marks.
   (4) Install the installation stop.
     (a) On the tube you do not move, put one end of the applicable snap-on coupling in the middle of the installation mark. The snap-on coupling will be the installation stop.
NOTE: As an alternative, you can use an applicable O-ring as an installation stop. Use the test coupling to put the O-ring in the correct position on the installation mark (perpendicular to the tube axis).
NOTE: You can also use the snap-on coupling to hold the tubes aligned while you do the tube set-up.
   (5) Decrease the temperature (chill) the installation tools.
     (a) Place the end of the tongs, the applicable tube chiller, and the applicable extended time tool in the workbox.
     (b) Keep the tools in the liquid nitrogen until the boiling stops.
   (6) Simulate and measure the time necessary for the installation.
     (a) With the test coupling, simulate the installation until you can do it easily. Make sure you know the obstructions that can prevent easy installation.
     (b) When you can do the installation easily, simulate the installation again, and measure the time necessary for the installation with a STOPWATCH.
     (c) Compare the time necessary to simulate the installation with the installation times given in the table.
If the time necessary to simulate the installation is more than the recovery time, use the extended time tool. Recovery time after tube chilling
Recovery time after tube chilling
Tube Size
Tube DIA in.
Tube DIA mm
Aluminum seconds
Stainless steel seconds
Titanium seconds
-04
1/4
6.35
30
45
35
-06
3/8
9.525
25
60
43
-08
1/2
12.70
22
75
50
-10
5/8
15.875
21
70
43
-12
3/4
19.050
20
62
35
-16
1
24.400
20
50
25
-20
1-1/4
31.750
20
50
25
-24
1-1/2
38.100
20
50
25
NOTE: The recovery times in this table are for the couplings in the plastic installation package. You can increase these times if you use the extended time tool. For repairs that add a length of new tube (splice), you can decrease the temperature (chill) the new tube before you start the installation. This will give you more time for the installation of the first coupling.
   (7) Chill the tubes.
     (a) Refer to the table below to find the correct chilling time for the tube type and the tube size.
Tube chilling time
Tube Size
Tube DIA in.
Tube DIA mm
Aluminum seconds
Stainless steel seconds
Titanium seconds
-04
1/4
6.35
40
40
40
-06
3/8
9.525
40
50
50
-08
1/2
12.70
40
60
60
-10
5/8
15.875
50
80
80
-12
3/4
19.050
70
110
100
-16
1
24.400
110
160
130
-20
1-1/4
31.750
150
180
140
-24
1-1/2
38.100
150
180
140
   (8) Install the coupling.
     (a) If you use the CRYOFIT couplings with plastic installation packages (as supplied pre-assembled from the factory):
       1 Put on the gloves.
       2 With the pre-chilled tongs, remove the coupling from the workbox.
       3 Hold the coupling with gloved fingers.
       4 Move the coupling on the tube end that does not have the installation stop.
       5 Align the tubes.
       6 Move the coupling back on the joint against the installation stop.
     (b) If increased recovery time is necessary, you must put the coupling in the extended time tool:
       1 Put on the gloves.
       2 With the pre-chilled tongs, remove the coupling from the workbox and remove the plastic installation package. Put the coupling back in the workbox.
       3 With the tongs, remove the pre-chilled extended time tool from the workbox and put it in your free gloved hand.
       4 Squeeze the tabs to open the jaws.
       5 Hold the extended time tool over the workbox, hold the coupling with the tongs and put it in the jaws (of the extended time tool).
       6 Carefully let the extended time tool fall back in the workbox.
       7 When the extended time tool is ready for installation (boiling stopped):
  • With the tongs, remove the extended time tool coupling from the workbox
  • Hold the tool with gloved fingers
  • Move the tool on the tube end that does not have the installation stop
  • Align the tubes
  • Move the tool back on the joint against the installation stop.
   (9) Remove the installation tool.
     (a) Let the coupling recover.
     (b) Remove the plastic installation package or the extended time tool.
   (10) Do a visual check.
     (a) Make sure that the two ends of the coupling touch the installation marks. If the two ends of the coupling are not on the installation marks, the repair is not satisfactory.
To make the repair satisfactory you can:
  • Cut out the coupling
  • Install a small length of new tube with two couplings (splice).
5. Close-up
Subtask 20-23-11-860-054-A
A. Put the Aircraft back to its Initial Configuration
   (1) Pressurize the hydraulic reservoirs (Ref. AMM TASK 29-14-00-614-002).
   (2) If necessary, fill the hydraulic reservoirs:
   (3) Pressurize the hydraulic systems for 15 minutes:
   (4) Make sure that there is no leakage in the repaired area.
   (5) Bleed the related hydraulic system:
     (a) For the Green system:
     (b) For the Yellow system:
     (c) For the Blue system:
     (d) For the normal braking system (Ref. AMM TASK 32-42-00-870-001).
     (e) For the alternate braking system:
   (6) If applicable, repair the protection on the repaired tube.
     (a) For aluminum tubes:
       1 Apply Surface Pretreatment-Light Alloys Chemical Conversion Yellow - (Material No.10ABC1) on the bare metal area of the tube with a brush.
       2 Complete the protection with Primer Polyurethane Paint_- Corrosion Inhibiting Structure (Material No.04EAC2) .
     (b) For Corrosion-Resistant Steel (CRES) tubes (if painted):
       1 Rub the bare metal area with PAD - ABRASIVE.
       2 Apply Wash Primer_- - Structure (Material No.04CMA2) on the bare metal area of the tube.
       3 Complete the protection with Primer Polyurethane Paint_- Corrosion Inhibiting Structure (Material No.04EAC2) .
   (7) Make sure that the work area is clean and clear of tools and other items.
[Rev.10 from 2021] 2026.03.31 22:59:33 UTC