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Wiring Harness Inspection

10 points

Overview

This assignment guides students in visually inspecting a wiring harness to identify common defects such as damaged wires, poor connectors, or insulation issues. Students will document their findings with a photo and a brief report, developing essential skills in harness condition assessment for safety and reliability.

Resources

FAA AC 43.13-1B - Chapter 11, Sections 8-12

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Assignment

Document Preparation

Copy this document to your own Coda E-portfolio page using the “Copy doc” button in the top right.

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Be sure to add it to the AT 209 section.

If you wish, you can hide this worksheet after completion by selecting “Hide page” from the page’s menu bar.

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Photograph Wiring Harness

Identify a wiring harness from an approved piece of equipment, such as a vehicle, plane, or training/simulator station.

Take a well-lit photo of the wiring harness.

Be sure to capture all ends of the wiring harness (it may run point to point or it may include several breakouts).

Upload your photo(s) to the

Photos⁠

section below.

Report of Findings

Conduct a brief visual inspection of the harness, focusing on the following:

Condition of the wires (check for cuts, cracks, abrasions, fraying, or exposed conductors)

Integrity of insulation and coverings (look for missing tape, damaged conduit, or heat damage).

Condition of connectors (check for corrosion, broken clips, loose or bent pins).

Signs of overheating (burn marks, melted insulation).

Routing and securing (whether the harness is adequately supported, tied down, and clear of moving parts or sharp edges).

Write a short

Inspection Observations⁠

(½ to 1 page maximum) that includes:

The photo of the harness.

A summary of your observations. Be sure that your observations use language represented in

FAA AC 43.13-1B - Chapter 11, Sections 8-12⁠

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Any defects or concerns you noticed.

A recommendation (e.g., “harness is acceptable for use,” “minor repair needed,” or “should be replaced”).

Photos

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Inspection Observations

Seen above is an image of a wiring harness found under the cowling of a Piper archer. This Archer is owned by Purdue University School of Aviation and Transportation Technology. The primary focus of this report will be conducted on the portion of the pictured wires which are the thinnest and white and yellow in color. It is evident off the bat that the wiring seen here is rather neat and tidy, but it is also important to not that this aircraft was down for maintenance. Therefore, it should be assumed that something is likely wrong with it, or it could just be due for routine maintenance. Either way, safety should not be assumed, and the wiring harness pictured will be examined. It is important to note that not all the wires are followed end to end, and this is because it would be impossible to follow all wires as they go under and around the engine in various patterns. The image above is configured the way seen because it provides the most clarity of the wires as they peek past the firewall and shows many splits in the wire.

Observations of this wiring harness were initially taken in a left to right fashion, and they were as detailed as possible in order to understand the full gravity of the situation as it applies to the maintenance of these components. Beginning from the right side of the image, the wiring harness protrudes out from the Archer’s firewall surrounded by a putty mixture, and this allows the wires to be able to withstand the virbations and fire hazards presented by being in such close proximity to the power plant. The wires are initially tightly bound together, and several retaining agents are used a few inches to the left of their start. These retaining bands or clips are present every few inches down the line of the wiring harness, and this allows the wires to take up less space and cause fewer problems as a result of interaction with other components compared to a reality in which they were not bound together.

In the central ground of the image pictured previously, it is evident that a large portion of the wires diverge from the main path, and what we essentially see is the emergence of two halves of the original bundle. This split is plannes well, and each side is thoughtfully retained with their own retaining agents. The top bundle of wires fades away to the dorsal side of the engine, and the bottom bundle of wires takes a sharp bend to the pectoral side of the engine. Both bands are pictured to have a specific retaining band which allows them to be supported by the metal structural members of the powerplant bay, and this further aids them in their quest not to waste or take up unnecessary space. Furthermore, the bottom strand is last pictured sharing a clamp with a metal and fabric fluids hose such that they can stabilize each other while maintaining a preselected distance from one another all the while.

The strands of both the top and the bottom bundle swiftly diverse into many indivudual wire strands outside the view of this image, and to capture each one would be madness. However, especially in this image, the wires seem to be in good health to the average eye. It is evident that there are no signs of fire or tears in the wiring harness, and it does not seem as though the harness has had any adverse reactions to vibration. It does not seem as though there have been any efforts to tamper with the wiring harness by maliscious individuals or animals either, as the wires are all held together very neatly and without spiraling. The insulation of the wire appears to have retained the entirety of its white or yellow color, as one would expect with healthy wires in a healthy harness. In addition, it is evident that the retaining clips, bands, and fasteners are all in the places they should be and are free of damage.

Inspection Specifics

In Advisory Circular AC 43.13-1B Chapter 11, sections 8-12, more specific definitions and descriptions of proper wiring harness inspections are detailed. It is this document that all wiring harness inspections should be checked with, and it contains highly useful information relating to the maintenance and repair of aviation grade electronics. The previously listed sections of the document were used in part to inspect the above image of a Purdue University Piper Archer wiring harness, although not every section culd be expanded upon because of the brevity of the visit taken to obtain the image of the harness. It would be fruitless to fully divulge into the topic with the wiring harness at hand because of the inexperience of the students in this course and the expertise required to understand the full terminology. However, many base line inspection items from the document as they relate to the wiring harness in question are detailed below.

Some general condition items called into question here include the state of the wires, cables, rubber fasteners, clamps, clamp retaining screws, insulation items, tapes, cable supports, and wire separation. All of these applicable items were found to be complient with the requirements of the advisory circular in terms of separation, totality, wholeness, lifespan, tension, placement, or decay. Also, No wires, terminals, fuses, connectors, or panels were foudn to be in need of being replaced because there was no presence of oxidization, fraying, breaking, tearing, discoloration, or absence. Electromagnetic interference tests and function tests could not be performed at the time of the photography of the above image, and therefore the entire picture of the use of the wiring harness components could be gathered, but the surface level items listed above tell most of the story as it related to inspection matters.

Furthermore, the wiring harness was not found to have an egregious level of slack, bend, kinking, looping, or separation from other components at the time of the observation, which are good things to avoid. There was no problem with the harness coming into contact with moisture, other components, heat, human occupants, or other wires, and the spacing of all components under the cowling was ideal. As a final note, service looping of the wires as well as all the associated clamps used in the harness assembly were found to be operationally sound, and there were no issues. As a final review of the topic, this wiring harness passes the basic parts of the inspection process as highlighted by Advisory Circular AC 43.13-1B Chapter 11, sections 8-12, but function testing would be the next step in understanding the soundness of the wiring harness. This harness is acceptable for use.