top of page


Public·8 members
Rezo Hunchback
Rezo Hunchback

AC 21-99: The Official Advisory Circular on Aircraft Wiring and Bonding

AC 21-99 Download: A Guide to Aircraft Wiring and Bonding

If you are involved in aircraft maintenance, you may have heard of AC 21-99. This is an advisory circular issued by the Australian Civil Aviation Safety Authority (CASA) that provides guidance material for maintenance of aircraft electrical systems and bonding of aircraft. In this article, we will explain what AC 21-99 is, why it is important for aircraft maintenance, how to download it, and what are the main topics covered by it.

ac 21-99 download

What is AC 21-99?

AC 21-99 stands for Advisory Circular 21-99. It is a document that provides advice and guidance to illustrate a means, but not necessarily the only means, of complying with the Civil Aviation Safety Regulations (CASR) Part 21. It also explains certain regulatory requirements by providing informative, interpretative, and explanatory material. When an AC is referred to in a Note below a regulation, the AC remains as guidance material. ACs should always be read in conjunction with the referenced regulations.

The purpose and scope of AC 21-99

The purpose of AC 21-99 is to provide guidance material for maintenance of aircraft electrical systems and bonding of aircraft. It covers topics such as wire and cable selection, identification, preparation, repair, soldering, lacing, tying, sealing, connectors, bonding, grounding, busbars, junction boxes, protective devices, terminal boards, thermocouple wire soldering and installation, aged aircraft wiring inspection and maintenance.

The scope of AC 21-99 applies to all ADF aircraft. It does not apply to civil registered aircraft operated by ADF or foreign military registered aircraft operated in Australia.

The status and revision of AC 21-99

This is the first issue of AC 21-99 to be written on aircraft wiring and bonding procedures. It was issued in November 2005. It may be revised or cancelled in the future depending on the changes in regulations or technology.

Why is AC 21-99 important for aircraft maintenance?

AC 21-99 is important for aircraft maintenance because it provides best practices and standards for ensuring the safety and reliability of aircraft electrical systems and bonding. By following the guidelines in AC 21-99, you can:

The benefits of following AC 21-99 guidelines

  • Reduce the risk of electrical fires, shorts, arcs, sparks, corrosion, interference, or failures that could compromise the performance or integrity of the aircraft or its systems.

  • Improve the efficiency and durability of the electrical components and wiring by using appropriate materials, methods, tools, and techniques.

  • Enhance the quality and consistency of the electrical work by using proper identification, marking, documentation, inspection, testing, and verification procedures.

  • Comply with the regulatory requirements and expectations of CASR Part 21 and other relevant authorities.

The risks of ignoring AC 21-99 recommendationsIgnoring the recommendations of AC 21-99 could result in:

  • Increased risk of electrical hazards, accidents, incidents, or injuries that could endanger the lives of the crew, passengers, or ground personnel.

  • Decreased performance, efficiency, or reliability of the electrical systems or components that could affect the operation or mission of the aircraft.

  • Increased cost, time, or complexity of the electrical maintenance, repair, or replacement due to poor quality, inconsistency, or non-compliance of the electrical work.

  • Potential legal, regulatory, or contractual liabilities or penalties for failing to meet the standards or requirements of CASR Part 21 or other relevant authorities.

How to download AC 21-99?

If you want to download AC 21-99, you have two options:

The official source of AC 21-99

The official source of AC 21-99 is the CASA website. You can access the document by following these steps:

  • Click on "Publications" in the top menu bar.

  • Click on "Advisory Circulars" in the left sidebar.

  • Click on "AC 21 - Certification and Airworthiness Requirements for Aircraft and Parts" in the list of categories.

  • Scroll down to find "AC 21-99 Aircraft Wiring and Bonding" and click on the link to download the PDF file.

The alternative sources of AC 21-99

If you cannot access the CASA website or prefer a different format, you can also find AC 21-99 from other sources. However, you should always check the validity and currency of the document before using it. Some of the alternative sources are:

ac 21-99 aircraft wiring and bonding pdf

ac 21-99(0) advisory circular

ac 21-99 annex g

ac 21-99 revision 2

ac 21-99 chapter 1

ac 21-99 section 2

ac 21-99 part 21

ac 21-99 manual of standards

ac 21-99 permissible unserviceabilities

ac 21-99 solderless terminations and splices

ac 21-99 electrical wire installation

ac 21-99 wire and cable identification

ac 21-99 soldering techniques

ac 21-99 lacing and tying wiring

ac 21-99 repairing wire and cable

ac 21-99 preparing wire and cable