DOC AIRBUS | AMM A320FSafetying with Lockwire
TASK 20-11-11-911-001-A
Safetying with Lockwire
The lockwire is installed to put tension on the wire when the parts become loose.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Job Set-up
Subtask 20-11-11-911-054-A
Subtask 20-11-11-911-061-A
Subtask 20-11-11-911-063-A
[Rev.10 from 2021]
2026.03.31 22:59:01 UTC
Safetying with Lockwire
WARNING:
USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.
1. Reason for the JobThe lockwire is installed to put tension on the wire when the parts become loose.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | PLIERS - TWISTING, SPECIAL |
| REFERENCE | DESIGNATION |
|---|---|
General Wirelocking RulesSubtask 20-11-11-911-054-A
A. General Wirelocking Rules
(1) Installation rules:
(a) Use lockwire only one time.
(b) Make sure that the lockwire is not damaged.
(c) It is not permitted to use lockwire to lock control cable turnbuckles.
(d) When you install lockwire, make sure that there will not be chafing or fatigue. This is to prevent damage to the lockwire or adjacent parts. The causes of chafing or damage are vibrations or increased tension on the wire to prevent loosening of the locked items.
(e) Wirelocking of installed flexible components or assemblies must not have an effect on the quality of the installation or the locking during operation.
(f) Do not use lockwire to prevent unwanted operation of controls or switches for normal, standby or emergency services which can be necessary during flight.
(g) It is not permitted to use lead seals attached to lockwire.
(h) The length of wire between the attachment points must be as short as possible.
(i) When you safety with lockwire in the fuel tank areas, make sure that there is no protrusion of the wire ends:
The minimum distance between a length of lockwire without support and parts that move is 15 mm (0.5906 in.).
(3) Wire direction
(a) General
The line of approach of the lockwire must be approximately tangential to the parts that you will lock.
When you install the lockwire, the strand that goes through the hole will tighten the locked item.
It is important to identify items with left hand and right hand threads carefully.
When you use an anchor lug, the wiring must start at the lug and the lug must align with the wire. The wire must not cause radial movement of the lug.
(b) Not adjacent items
When the wire goes across the body of the item that you must lock, the angle of approach of the wire (in relation to the longitudinal axis of the item) must be a minimum of 45°.
(4) Equivalent wirelocking standards:
Subtask 20-11-11-911-055-A (1) Installation rules:
(a) Use lockwire only one time.
(b) Make sure that the lockwire is not damaged.
(c) It is not permitted to use lockwire to lock control cable turnbuckles.
(d) When you install lockwire, make sure that there will not be chafing or fatigue. This is to prevent damage to the lockwire or adjacent parts. The causes of chafing or damage are vibrations or increased tension on the wire to prevent loosening of the locked items.
(e) Wirelocking of installed flexible components or assemblies must not have an effect on the quality of the installation or the locking during operation.
(f) Do not use lockwire to prevent unwanted operation of controls or switches for normal, standby or emergency services which can be necessary during flight.
(g) It is not permitted to use lead seals attached to lockwire.
(h) The length of wire between the attachment points must be as short as possible.
(i) When you safety with lockwire in the fuel tank areas, make sure that there is no protrusion of the wire ends:
- For the single wire method, you must twist the wire end with protrusion back to the wire.
- For the double wire method, you must bend the wire ends with protrusion back to the wire or the part that you lock (e.g. screw/nut).
The minimum distance between a length of lockwire without support and parts that move is 15 mm (0.5906 in.).
(3) Wire direction
(a) General
The line of approach of the lockwire must be approximately tangential to the parts that you will lock.
When you install the lockwire, the strand that goes through the hole will tighten the locked item.
It is important to identify items with left hand and right hand threads carefully.
When you use an anchor lug, the wiring must start at the lug and the lug must align with the wire. The wire must not cause radial movement of the lug.
(b) Not adjacent items
When the wire goes across the body of the item that you must lock, the angle of approach of the wire (in relation to the longitudinal axis of the item) must be a minimum of 45°.
(4) Equivalent wirelocking standards:
| Metric standard (mm) | US standard (inch) |
|---|---|
| 0.4 | 0.015 |
| 0.5 | 0.020 |
| 0.6 | 0.025 |
| 0.8 | 0.032 |
| 0.9 | 0.035 |
| 1 | 0.041 |
| 1.25 | 0.051 |
| 1.6 | 0.063 |
B. Additional Pipe Wirelocking Rules
(1) When you connect a pipe to a plug-in union, lockwire the pipe swivel nut to the component and not to the plug-in union.
(2) You can lock the adjacent plug-in unions or swivel nuts together.
(3) Do not use the same wire to lock more than two plug-in unions or swivel nuts.
Subtask 20-11-11-911-056-A (1) When you connect a pipe to a plug-in union, lockwire the pipe swivel nut to the component and not to the plug-in union.
(2) You can lock the adjacent plug-in unions or swivel nuts together.
(3) Do not use the same wire to lock more than two plug-in unions or swivel nuts.
C. Wirelocking Methods
(1) Double wire method:
The recommended method is the "double-twist method".
The maximum distance between fasteners is 100 mm (3.94 in.).
If the distance is more than 100 mm (3.94 in.):
(2) Single wire method:
Use only the single wire method if specified in the related task.
The maximum length of lockwire is 600 mm (23.62 in.).
Subtask 20-11-11-911-057-A (1) Double wire method:
The recommended method is the "double-twist method".
The maximum distance between fasteners is 100 mm (3.94 in.).
If the distance is more than 100 mm (3.94 in.):
- Use one more attachment point.
- The maximum length of wire is 600 mm (23.62 in.).
(2) Single wire method:
Use only the single wire method if specified in the related task.
The maximum length of lockwire is 600 mm (23.62 in.).
D. Precautions Before Wirelocking
(1) Make sure that all lockwire holes are drilled.
(2) Make sure that the assembly was torqued to the requirements of the related task.
4. Procedure(1) Make sure that all lockwire holes are drilled.
(2) Make sure that the assembly was torqued to the requirements of the related task.
Subtask 20-11-11-911-061-A
A. Double Wirelocking
(1) Put the lockwire into the hole of the fastener.
(3) Bend this lockwire end around the other lockwire end.
(4) Use PLIERS - TWISTING, SPECIAL to twist the lockwire clockwise at a maximum angle of 60°:
Keep the lockwire tight during the twisting, until the twisted part comes very near to the hole in the next unit.
(5) Pull one lockwire end through the fastener head (2) when the twisted part is near it (less than 3 mm (0.1181 in.)).
For wirelocking of 3 nuts or bolt heads, twist the lockwire in one direction between the first two items. Then twist it in the opposite direction between the second and third items.
(7) Twist the strands in the direction that will cause the lower lockwire to always be pulled down.
The length of this twisted part (pigtail) must be between 10 mm (0.39 in.) minimum and 15 mm (0.59 in.) maximum.
(8) If necessary, cut and discard the unwanted length of lockwire:
(10) When you safety with lockwire in the fuel tank areas, make sure that you bend the wire ends with protrusion along the wires. You must also make sure that the wire ends stay near to the wire or the part that you lock.
(11) Make sure that there is tension in the lockwire.
(12) Make sure that there are no signs of damage (nicks, kinks) on the lockwire. This does not include the abrasion caused by the PLIERS - TWISTING, SPECIAL.
Subtask 20-11-11-911-062-A (1) Put the lockwire into the hole of the fastener.
NOTE: There must be the same length of lockwire on each side of the fastener.
(2) Bend one lockwire end around the fastener head (1) to the fastener head (2). (3) Bend this lockwire end around the other lockwire end.
(4) Use PLIERS - TWISTING, SPECIAL to twist the lockwire clockwise at a maximum angle of 60°:
- Do not put too much tension on the wire.
- To prevent damage to the lockwire during this step, refer to the table that follows:
| Diameter of lockwire | Number of twists (for 10 mm) (0.39 in.) |
|---|---|
| 0 mm (0.0000 in.) to 0.5 mm (0.0197 in.). | 4 - 7 |
| 0.5 mm (0.0197 in.) to 1.25 mm (0.0492 in.). | 3 - 5 |
| 1.25 mm (0.0492 in.) to 2.0 mm (0.0787 in.). | 2 - 4 |
| More than 2.0 mm (0.0787 in.). | 2 - 3 |
(5) Pull one lockwire end through the fastener head (2) when the twisted part is near it (less than 3 mm (0.1181 in.)).
For wirelocking of 3 nuts or bolt heads, twist the lockwire in one direction between the first two items. Then twist it in the opposite direction between the second and third items.
NOTE: The direction of the wrap and the twisted strands must be such that the loop around the part comes below the strands that go out of the hole. Thus the loop will stay down and will not become loose.
(6) Pull the other lockwire end around the fastener head (2). (7) Twist the strands in the direction that will cause the lower lockwire to always be pulled down.
The length of this twisted part (pigtail) must be between 10 mm (0.39 in.) minimum and 15 mm (0.59 in.) maximum.
(8) If necessary, cut and discard the unwanted length of lockwire:
- You must collect the cut-off material to prevent damage to the aircraft.
(10) When you safety with lockwire in the fuel tank areas, make sure that you bend the wire ends with protrusion along the wires. You must also make sure that the wire ends stay near to the wire or the part that you lock.
(11) Make sure that there is tension in the lockwire.
(12) Make sure that there are no signs of damage (nicks, kinks) on the lockwire. This does not include the abrasion caused by the PLIERS - TWISTING, SPECIAL.
B. Single Wirelocking
(1) Put the lockwire into the locking hole of the bolt (1) (see detail A).
(2) Keep the lockwire tight, twist a minimum of four times.
(3) Put one end of the lockwire through the locking hole of the bolt (2) (see detail B).
(5) Pull the lockwire tight and make it go around and below itself again until you get between two and four full turns.
(6) If necessary, cut and discard the unwanted length of lockwire:
(8) Make sure that there are no signs of damage (nicks, kinks) on the lockwire.
5. Close-up(1) Put the lockwire into the locking hole of the bolt (1) (see detail A).
(2) Keep the lockwire tight, twist a minimum of four times.
(3) Put one end of the lockwire through the locking hole of the bolt (2) (see detail B).
NOTE: Airbus recommends that you do not cut the end that is not used until the wirelocking operation is completed. You can use it if the first end breaks.
(4) Bend the lockwire back by 180° and below itself (see detail C). (5) Pull the lockwire tight and make it go around and below itself again until you get between two and four full turns.
(6) If necessary, cut and discard the unwanted length of lockwire:
- You must collect the cut-off material to prevent damage to the aircraft.
(8) Make sure that there are no signs of damage (nicks, kinks) on the lockwire.
Subtask 20-11-11-911-063-A
A. Check of the Wirelocking
(1) Discard the remaining wire.
(2) Remove all pieces of cut-off lockwire from the aircraft structure.
(1) Discard the remaining wire.
(2) Remove all pieces of cut-off lockwire from the aircraft structure.