Diagnostic Tools for the Next Generation

What are the best troubleshooting tools for the aircraft mechanic?


During my early and more formative years in aviation maintenance I had the opportunity to work with an old electrician (probably about 50 then). Vince had been a career enlisted man in the Air Force and had his hands all over many of the most sophisticated aircraft of the day.

At that time we both were working production flight test for the manufacturer of business jets. The job was hectic trying to get the bugs and gremlins exterminated prior to the aircraft being turned over to the new owner. When an electrical or avionics glitch was reported, some of the aircraft crew chiefs would request several of the younger (and perceived to be sharper) electricians.

Vince was known to take more time to get the aircraft back in the air. I did take notice of this tendency and even queried one of the more senior crew chiefs. He suggested I start to look at the trends of reoccurring problems.

Get as much info as possible

On the whole, our department had a very good record of fixing broken aircraft but Vince was batting 1,000. He attempted to get as much information as he could about the nature of the discrepancy as well as understand as much as possible about the proper operation of the system. Once he could fully comprehend what should happen and what the flight crew observed he would lay out a detailed plan of attack using schematics and wiring diagrams. Prior to heading to the aircraft, a trip to the equipment locker would yield necessary breakout boxes or specific system testers. He once told me the only tool really needed for electrical testing is a basic multimeter and an assortment of test leads.

Over the years it has been my privilege to work with many brilliant technicians and as a result many little known tricks of the trade have been properly archived. My realization, we can troubleshoot many electrical systems with nothing more than a magnetic stud finder and a lamp of appropriate voltage with test leads attached. Although not normally associated by many with the digital aircraft of today; these tools and techniques will most likely still be employed well after I retire and in the proper hands can reveal many anomalies.

Toolbox of the future

So what will the toolbox of a next generation aircraft technician consist of? It would be easy to spend thousands of dollars on various types of analyzers and bus readers but will the investment be justified and will the specialized equipment be regularly used? Hand tools such as wire strippers will still need to be suitable for the type of wire along with terminal end crimpers and wire tie pullers. Strange as it may sound, overtightening a wire tie can compress insulation and alter impedance of a digital bus or coax. Calibration again is an important factor.

Aircraft salespeople state that with the sophisticated nature of their product; the onboard computer diagnostics will virtually eliminate the need for troubleshooting. I guess that is why they are salespeople. The majority of built-in diagnostics will only detect signal out of tolerance (SOT) conditions and do not have the ability to reason. Aircraft manufactured in recent years probably have at least some digital technology onboard. This is greatly expanded in machines such as the single engine Cirrus up through the Airbus 380 and most fly-by-wire systems unlike cable operated flight controls have limited need of a cable tensiometer.

One of the leading causes of electronic component failure is electro static discharge (ESD). With that in mind, ESD wrist straps along with a static friendly work surface are paramount for working on a digital aircraft.

Oscilloscopes might be considered the VOM of the future. While they do enable the user to accomplish the traditional meter functions, they will graphically display problems you can’t detect otherwise. With information sampling rates that can keep up with even the highest speed data transfer and the potential for memory storage to hold sample readings for further evaluation, a portable Scopemeter captures and displays waveforms, noise, and other disturbances in great detail.

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