The A320 ATA 20 Technical Notes are brief and to-the-point information about the Airbus A320 airframe standard practices chapter.


The Airbus A320 airframe standard practices chapter contains information on the use and application of aircraft maintenance and repair processes which are not specifically covered in other chapters of the Aircraft Maintenance Manual. It also gives the list of materials required for servicing and maintenance operations.


  • Safetying with Lockwire
  • Safetying with a Cotter Pin
  • Handling Precautions for ESDS Devices
  • Circuit Breakers Safety Practices
  • Maintenance in Storm Conditions – Safety Practices
  • Find the standard torques – tightening torques for:
    • Standard threaded fasteners,
    • Pipes unions (not for oxygen),
    • Flight control threaded fasteners,
    • Oxygen unions,
    • Electrical component fasteners.
  • Find the installation and repair of tubings
  • Control Cables – Installation / Cleaning and Protection / Inspection
  • Electrical Bonding – ATA 20
  • Aircraft Grounding (Earthing) – ATA 12
  • Detailed Inspection of Bonding Leads on Access Panels, Doors and Movable Surfaces
  • Removal/Installation of an O-ring (Hydraulic Systems)
  • List of materials required for aircraft service and maintenance
    • The list of consumable materials is given in the Consumable Material List (CML)
    • AMM usually gives the CML item number, except for new materials referenced by an Application code.
    • AMM does not give specific Warnings for consumable materials because the related precautions are given in the applicable Material Safety Data Sheet. For more information about the Material Safety Data Sheets, refer to the CML Introduction.
    • For some applications in the AMM procedures, there can be alternative materials. These materials have the same item number as the basic material but with a suffix letter (A, B, C, etc.).
    • (Example: 06-001A, 06-001B & 06-001C are alternatives of 06-001).
    • list of approved oil brand names for APU and IDG servicing.
      • Because APU and IDG come under Airframe System
    • for lubricant grease specification – ATA 12.
    • Electrical standard procedures – ESPM
  • Marking of the Unions after Application of Standard or Specific Tightening Torque

Information related to the various standards effective for all AIRBUS models are given in a separate manual called STANDARDS MANUAL. It contains information about all product/semi-finished product standards approved by the Airbus partners for the Airbus programs, as well as about the proprietary parts and the suppliers qualified for those parts.

Circuit Breakers Safety Practices

  • It is necessary to safety an open circuit breaker with safety clips (CB COLLAR) during:
    • Operation for a not activated optional system or a deactivated system because of MMEL requirements.
    • Maintenance when there is work on an electrically controlled or supplied system.
  • Not activated optional system
    • White color safety clips
    • Secure the safety clips with stainless steel lockwire
  • Deactivated system
    • Install red color safety clips
    • Secure the safety clips with stainless steel lockwire
  • Maintenance
    • Install red color safety clips
    • Safety tag on related CB.

Maintenance in Storm Conditions – Safety Practices

  • Make sure that aircraft is grounded
  • Stop ground servicing operations external to the aircraft (refueling, etc.).
  • Disconnect all other external connections (external power supply, etc.)
  • Remove or disconnect the headsets.
  • Not touch metal parts, equipment or connections to the aircraft.

Tightening Torques for Standard Threaded Fasteners

  • The threaded fasteners are identified with a standard number written on the head (example: ABS, AN, ASNA, NAS, ASN, NSA, MS). They are installed in standard conditions and lubricated.
  • It is necessary to know the fastener standard and diameter to know the correct tightening torque.
  • The tightening torques of the TAPERLOK, HI-LOK, and HI-LITE screws are specified in the given procedures Ref. SRM 51-49-00.
  • Do not use aluminum, titanium and Inconel nuts again.
  • Do not use self-sealing nuts again.
  • Do not use self-locking nut (this includes castellated nuts with a nylon ring)
  • Limits for captive nuts – feel the breakaway torque resistance
  • Fasteners Installed on Uncured Interfay Sealant – torque after 30 minutes

Marking of Unions after Torque

Marking of the Unions after Application of Standard or Specific Tightening Torque – AMM

  • This is to identify a tightened union
  • This is to show possible loosening of the union
  • To make marks on the torqued unions of these systems:
    • Hydraulic
    • Oxygen
    • Fuel
    • Ice and rain protection
    • Fire protection
    • Pneumatic
    • Water
  • Do not put the marks on the torqued unions installed in the fuel tanks, where the torqued unions have a layer of sealant.

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