AET Aircraft Wiring Practices and Standards

Question 1

Which wire specification is the current standard for most aircraft applications due to its lightweight PTFE insulation?

Accepted Answer

SAE AS22759 / MIL-W-22759 (PTFE-insulated)

Answer

SAE AS22759 (formerly MIL-W-22759) uses PTFE (Teflon/Tefzel) insulation, which provides excellent heat resistance, low weight, and durability — making it the current standard for most aircraft wiring applications.

Question 2

What is the preferred method for splicing aircraft wiring according to FAA Advisory Circular 43.13-1B?

Accepted Answer

Approved crimp splices with calibrated crimp tools

Answer

Crimp splices using approved tools and correct positioners are the preferred method for aircraft wiring splices. They produce consistent, reliable connections without the risk of cold solder joints or flux contamination associated with soldering.

Question 3

What is the purpose of using shielded wire in aircraft wiring systems?

Accepted Answer

To protect the signal from electromagnetic and radio frequency interference (EMI/RFI)

Answer

Shielded wire surrounds the conductor(s) with a conductive braid or foil that is grounded at one end, preventing external EMI/RFI from inducing noise into sensitive signal lines such as audio, sensor, and data bus wiring.

Question 4

According to aircraft wiring standards, what is the minimum bend radius typically required when routing a wire bundle to prevent insulation damage?

Accepted Answer

Three times the outside diameter of the wire bundle

Answer

AC 43.13-1B specifies that wire bundles should not be bent to a radius less than three times the outside diameter of the bundle. Tighter bends stress the insulation and conductors, potentially causing cracks or breaks.

Question 5

When terminating aircraft wiring with a circular MS-series (MIL-DTL-38999) connector, what is the most critical requirement for the crimping operation?

Accepted Answer

Use the correct approved positioner and die set matched to the specific contact size and wire gauge

Answer

Approved crimp tool positioners and dies are engineered to produce the precise crimp geometry (height and width) required for each specific contact size and wire gauge combination. Using incorrect tooling will produce a non-conforming crimp that can fail in service.

(AET) Aircraft Electronics Technician Practice Test

(AET) Aircraft Electronics Technician Practice Test

AET Aircraft Wiring Practices and Standards