DOC AIRBUS | AMM A320FSafetying with a Cotter Pin
TASK 20-11-11-911-802-A
Safetying with a Cotter Pin
Self Explanatory
2. Job Set-up Information
A. Referenced Information
3. Job Set-up
Subtask 20-11-11-911-064-A
Subtask 20-11-11-911-065-A
Subtask 20-11-11-942-050-A
[Rev.10 from 2021]
2026.03.31 22:59:02 UTC
Safetying with a Cotter Pin
WARNING:
USE PROTECTIVE GOGGLES WHEN YOU REMOVE OR INSTALL A COTTER PIN. EACH TIME YOU REMOVE A COTTER PIN DURING THE TASK, DISCARD IT IMMEDIATELY. A LOOSE COTTER PIN CAN CUT YOU OR MAKE YOU BLIND.
1. Reason for the JobSelf Explanatory
2. Job Set-up Information
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| TASK 20-21-11-911-001-A | Tightening Torques for Standard Threaded Fasteners |
Location of the Cotter Pin Hole After the Installation of the NutSubtask 20-11-11-911-064-A
A. Precautions before Installation of the Cotter Pin
(1) If you install the cotter pin on a fastener with a thread, make sure that the fastener is tightened to the correct torque value.
Refer to:
(2) Refer to the related installation task to:
(a) If the cotter pin hole is more than a half hole above the top of the castellated nut or slotted nut:
1 Install a washer below the nut (with the same material and protection used for the nut, refer to the IPC).
2 If there is more than half a hole above the top of the nut, install two washers (one below the nut and one below the bolt/screw head).
Do not install more than two washers below the nut.
3 If there is more than half a hole above the top of the nut, replace the bolt/screw by a shorter bolt/screw.
(4) Make sure that the cotter pin hole and the castellations or the slots on the nut are not damaged.
(5) Do not make the cotter pin hole, the castellation or the slot on the nut/collar large to engage the cotter pin.
(6) Make sure that the cotter pin is not damaged.
4. Procedure(1) If you install the cotter pin on a fastener with a thread, make sure that the fastener is tightened to the correct torque value.
Refer to:
- The related task to install the fastener, or
- The standard torque value (Ref. AMM TASK 20-21-11-911-001).
(2) Refer to the related installation task to:
- Install the applicable washer below the castellated nut or the slotted nut, if necessary.
- Install the applicable washer on the pin, if necessary.
- Find the correct Illustrated Parts Catalog (IPC) reference for the cotter pin.
NOTE: The standard Part Number (P/N) of the cotter pin gives information of its material and dimension.
NOTE: Cotter pins installed on the parts that turn have a length of approximately two times the pin or the rod end diameter.
(3) Make sure that the cotter pin hole is not above the top of the castellated nut or the slotted nut. (a) If the cotter pin hole is more than a half hole above the top of the castellated nut or slotted nut:
- Make sure that the assembly (bolt/screw and necessary washer(s)) is correct in relation to the IPC references.
1 Install a washer below the nut (with the same material and protection used for the nut, refer to the IPC).
2 If there is more than half a hole above the top of the nut, install two washers (one below the nut and one below the bolt/screw head).
Do not install more than two washers below the nut.
3 If there is more than half a hole above the top of the nut, replace the bolt/screw by a shorter bolt/screw.
(4) Make sure that the cotter pin hole and the castellations or the slots on the nut are not damaged.
(5) Do not make the cotter pin hole, the castellation or the slot on the nut/collar large to engage the cotter pin.
(6) Make sure that the cotter pin is not damaged.
NOTE: It is not permitted to use cotter pins more than one time.
Subtask 20-11-11-911-065-A
A. Cotter-Pin Installation on Parts that do not Turn
(1) First procedure for cotter pin installation on castellated or slotted nuts (anchor procedure)
(a) Engage the cotter pin through the hole with the plane of its head perpendicular to the bolt/screw axis.
(b) Push the cotter pin through the hole until its head touches the nut but does not touch the thread.
(c) Bend the prongs of the cotter pin against the sides of the nut with pliers or bend the prongs rearward into the adjacent slots of the nut.
(d) Cut the unwanted length of prong.
(2) Second procedure for cotter pin installation on castellated or slotted nuts (anchor procedure)
(a) Make sure that the bolt/screw is less than one and half threads above the nut.
(b) Engage the cotter pin in the hole with the plane of its head parallel to the bolt/screw axis.
Do not use too much force to engage the cotter pin.
(c) Push the cotter pin in the hole until its head touches the nut but does not touch the thread.
(d) Bend the prongs of the cotter pin with pliers:
The bottom prong must not be above the area of the nut or washer.
Subtask 20-11-11-911-066-A (1) First procedure for cotter pin installation on castellated or slotted nuts (anchor procedure)
(a) Engage the cotter pin through the hole with the plane of its head perpendicular to the bolt/screw axis.
(b) Push the cotter pin through the hole until its head touches the nut but does not touch the thread.
(c) Bend the prongs of the cotter pin against the sides of the nut with pliers or bend the prongs rearward into the adjacent slots of the nut.
(d) Cut the unwanted length of prong.
(2) Second procedure for cotter pin installation on castellated or slotted nuts (anchor procedure)
(a) Make sure that the bolt/screw is less than one and half threads above the nut.
(b) Engage the cotter pin in the hole with the plane of its head parallel to the bolt/screw axis.
Do not use too much force to engage the cotter pin.
(c) Push the cotter pin in the hole until its head touches the nut but does not touch the thread.
(d) Bend the prongs of the cotter pin with pliers:
- Put the top prong tightly against the shank of the bolt/screw
- Put the bottom prong tightly against the face of the nut.
The bottom prong must not be above the area of the nut or washer.
B. Cotter-Pin Installation on the Parts that Turn
(1) Make sure that the cotter pin length is approximately two times the pin or rod end diameter.
(2) Engage the cotter pin in the hole of the rod end (or pin), and make sure that the plane of the cotter-pin head is perpendicular to the rod (or pin) axis.
(3) Push the cotter pin in the hole until its head touches the pin or rod end shank.
(4) Bend the prongs of the cotter pin around the pin or rod end shank with pliers.
The prongs of the cotter pin must be tightly bent against the shank.
(5) Make sure that the prong length is in the limits.
If necessary, cut the unwanted length of prong.
Subtask 20-11-11-911-067-A (1) Make sure that the cotter pin length is approximately two times the pin or rod end diameter.
(2) Engage the cotter pin in the hole of the rod end (or pin), and make sure that the plane of the cotter-pin head is perpendicular to the rod (or pin) axis.
(3) Push the cotter pin in the hole until its head touches the pin or rod end shank.
(4) Bend the prongs of the cotter pin around the pin or rod end shank with pliers.
The prongs of the cotter pin must be tightly bent against the shank.
(5) Make sure that the prong length is in the limits.
If necessary, cut the unwanted length of prong.
C. Removal of an Assembled Cotter Pin
(1) If necessary, use applicable pliers and/or a wire cutter to remove the assembled cotter pin. Make sure that there is no damage to the bolt/screw threads, nuts or the structure.
(2) Remove all the remaining parts of the cotter pin from the aircraft structure and discard them.
5. Close-up(1) If necessary, use applicable pliers and/or a wire cutter to remove the assembled cotter pin. Make sure that there is no damage to the bolt/screw threads, nuts or the structure.
(2) Remove all the remaining parts of the cotter pin from the aircraft structure and discard them.
Subtask 20-11-11-942-050-A
A. Make sure that the work area is clean and clear of tools and other items.