Aging Aircraft Wiring: Fault prevention and detection issues

Let's face it, the average age of the nation's aircraft fleet is getting older. As we struggle to maintain these older aircraft, aging wiring issues come to the forefront of critical issues.

The 900 AST is the size of a typical digital multimeter. In addition to offering all of the functions of a digital multimeter, the 900 AST offers a time domain reflectometer (TDR) to identify the distance to an open circuit as well as a function called resistive fault locate (RFL) that calculates the distance to a short or ground.

The TDR on the 900 AST can examine single conductor wires with a reference wire, twisted pair cables, shielded wires, and coax cables.

While the TDR function of the unit works well with open circuits, it does not detect all faults or grounds. This is where the RFL function comes in. This function will display the distance to a fault or ground accurately. A color-coded ground on the screen shows the mechanic how to set up this test.

The 900 AST has the ability to store up to 200 TDR traces in its internal memory. Past traces can be recalled in order to compare it to a live trace. In addition, wire traces can be uploaded to a computer using a built-in infrared port.

ESP Meter

Eclypse International Corporation has launched its own fault location meter. Dubbed the ESP Meter, it can also locate faults in wiring. It uses Standing Wave Reflectometry to locate faults in wiring up to 1,000 feet. It can also store data and link to a PC for upload via a RS-232 data port. It is being deployed for operational evaluation with units at Marine Corps Air Station, Cherry Point, NC and Tinker AFB in Oklahoma.

The technology available to help us do our jobs is increasing each day. With these additional tools available, mechanics may be able to meet the demands that aging wiring poses to the safe operation of the aircraft we work on. AMT

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