W DOC AIRBUS | AMM A320F

Tightening Torques for Electrical Component Fasteners

TASK 20-21-15-912-001-A
Tightening Torques for Electrical Component Fasteners

1. Reason for the Job
To give the tightening torques for electrical component fasteners.
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
SCREWDRIVER - CALIBRATED
No specific
AR
WRENCH - TORQUE
 B. Consumable Materials
REFERENCE
DESIGNATION
(Material No.04SAB2)
Varnish Polyurethane-- Marking Structure
 C. Referenced Information
REFERENCE
DESIGNATION
ESPM 2051500
F Tightening Torques for Electrical Components
F Tightening Torques for Electrical Components
F Marking of Screws and Nuts
3. Job Set-up
Subtask 20-21-15-941-050-A
A. Functions
   (1) The application of tightening torques on electrical component fasteners permits:
  • the electrical and mechanical connection of a terminal to the component
  • the mechanical attachment of the component to its support
  • the mechanical connection of the various component parts, one with the other
  • the removal and installation of the fasteners for maintenance.
   (2) For standard items, use the ESPM search tool to find the correct tightening torque value ESPM 2051500.
4. Procedure
Subtask 20-21-15-912-050-A
A. General Requirements and Precautions
   (1) You must tighten the fasteners with a WRENCH - TORQUE and SCREWDRIVER - CALIBRATED.
   (2) Do not change the original lubrication of the hardware.
   (3) To install a nut on a stud or a bolt in a nut:
     (a) Align the two components axially.
     (b) Apply a light pressure and turn "to loosen" until you feel a click on the first thread.
     (c) Turn "to tighten" by two turns.
     (d) TORQUE with the applicable tool.
       1 When you have a stacked assembly with the bolt or the nut in contact with the components, manually make sure that the components are in the correct position before you apply the torque.
       2 Apply the tightening torque in one continuous operation.
NOTE: If you do not apply the torque in one continuous operation (limited travel or access), do the last tightening operation with a sufficient movement (with a rotation of 30 degrees minimum).
Subtask 20-21-15-912-051-A
B. Special Requirements and Precautions
   (1) Connection fasteners
Use a wiring principle that prevents stress in the cables that can cause loosening of the fasteners.
   (2) Attachment fasteners
When the diameter of the attachment fasteners is less than the diameter of the connection fasteners:
  • make sure that you do not cause damage to the attachment of the component on the support when you apply the torque to the connection fasteners.
   (3) fasteners for assembly/locking
You must not use the nuts and bolts to assemble or mate the components. The fasteners must be used only to finalize the operation.
   (4) Electrical connections that are not used
     (a) Terminal studs that are not used
Remove the nut and leave the stud free.
     (b) Others
Tighten the connection screws and nuts to the specified torque values.
   (5) Limitation of use
     (a) You cannot use the self-locking nuts again.
     (b) For other types of fasteners, you can use them again in these conditions:
  • The threads and mating surfaces are not damaged.
  • The protection of the fasteners and the surface condition is not damaged.
NOTE: If you use the bolts and nuts again, this:
  • Makes the pre-tension weaker because it decreases the satisfactory effect of the lubricant.
  • Causes local damage to the protection of the bolts and nuts which can cause corrosion or seizing.
  • Can cause damage the mating surfaces.
  • Can decrease the torque for the self-locking nuts.
Subtask 20-21-15-210-050-A
C. Visual Inspection before Application of the Tightening Torque
   (1) Before you apply the tightening torque, make sure that:
     (a) The old identification mark (red mark) is removed (if painted).
NOTE: You must not use the red mark as a visual reference for tightening of the fasteners.
     (b) The quality of the bolt and nut threads and of the lubrication is correct.
     (c) The tightening tools agree with the bolts and nuts.
     (d) The chamfer of the bolt is higher than or equal to the depth of the thread.
     (e) The terminals are flat and without burrs.
Subtask 20-21-15-912-052-A
D. Application of the Tightening Torque
   (1) Apply the tightening torques to the fasteners.
F Tightening Torques for Electrical Components
F Tightening Torques for Electrical Components
Subtask 20-21-15-210-051-A
E. Visual Inspection after Application of the Torque.
   (1) After you apply the torque, make sure that:
     (a) The position of the assembled components has not changed.
     (b) The terminals are parallel.
     (c) The components are correctly locked.
     (d) You can see at least one thread and a half above the nut.
   (2) Apply the identification mark (red mark) if it is necessary.
Subtask 20-21-15-912-053-A
F. Marking of Screws and Nuts (identification mark)
   (1) After application of the tightening torque, on electrical connections held by a nut or a screw (except circuit-breakers) and made with cables with a cross-section of 5 mm2 or more (size 10 - 8 - 6, etc), you must make an identification mark (red painted line) between the nut or screw head and a fixed point using Varnish Polyurethane-- Marking Structure (Material No.04SAB2) .
F Marking of Screws and Nuts
NOTE: You must not use the red mark as a visual reference for tightening of the screw or the nut.
You must remove this mark before any operation on the connection.
After an operation, you must tighten the screw or the nut to the applicable torque value and repaint the red mark.
[Rev.10 from 2021] 2026.04.01 05:49:42 UTC
"Aviabrain" 2025