Diagnostic Tools for the Next Generation

What are the best troubleshooting tools for the aircraft mechanic?

Newer versions will allow simultaneous monitoring of up to four data lines while smaller units almost rival the traditional volt/ohm meter (VOM) when it comes to the amount of space occupied in the toolbox. Transitioning from a multimeter to an oscilloscope will require some patience and it may be prudent to seek guidance from someone who has used them as proper setup is essential to obtaining usable information in the circuit testing process.

Calibration and cost

Like with any piece of equipment used to verify airworthiness, periodic calibration is needed. In some cases buying a new unit direct from the manufacturer does not ensure proper calibration. Often the certificate has to be requested at the time of sale and may be a negotiable part of the final price.

Cost of Scopemeters has been a factor prohibiting many technicians from having a personal device. In recent years the price has dropped with very basic units priced in the same general area as a good multimeter. It is not uncommon however to plan on a quote of anywhere from $1,100 to $4,000 depending on features and accessories.

Virtually all of the options compatible with a VOM will work with a Scopemeter. Some of the most common include an amp clamp for sensing current flow and a thermal sensor which can turn a testing device into a digital thermometer. A broad selection of test leads is a must for an aircraft technician along with a spare probe to be used with the scope features.

A signal tracer is another good value and consists of an audio signal generator and a portable signal sensing probe. The audio generator can be attached to the circuit in question and the probe can then sense where the signal can go. This is very effective when it comes to locating nonshielded wires or remotely located components. In many cases the sensitivity of the probe will enable the user to detect the presence of electrical noise at potential points of entry into sensitive circuits.

PCs and smartphones

In the computer age what could be a more appropriate tool than a portable computer?

Many aircraft, engine and avionics manufacturers have stopped producing paper documentation and depend on some form of electronic media. In addition, software is a frequent tool to allow a PC to interface with various airframe systems to facilitate data downloads and/or troubleshooting. Even Smartphones have found a place in the aircraft technician’s toolbox. Arguably the primary purpose is to stay connected by either voice or data transmission but newer applications can turn one of these devices into a WiFi signal analyzer, sound meter, flashlight, vibration analyzer, and even a pocket reference guide.

Troubleshooting digital systems does involve a certain finesse along with a strong constitution as reported problems are frequently related to software glitches and don’t have anything to do with system bussing. Although, when an actual bus problem does occur, it is important to consider all the possible factors. High resistance connections, improper insulation, or even capacitance value of the conductors will impact data flow.


Probably the most important tool to achieve success in the future is knowledge. Understanding principals of operation along with specific system capabilities will undoubtedly provide a solid foundation for building the most effective toolbox necessary for the challenges of the future. Proper education coupled with suitable training can create an awareness of just what can be accomplished with the equipment at hand.

It is always preferable to be well versed in using the tried and true tools rather than having all the latest and greatest whizbang devices but not a clue in their use.

Some still look as a data bus for what it really is: nothing more than pairs of wires twisted together. What could possibly be difficult in troubleshooting something as simple as that? Maybe my old buddy Vince had something when he said he could fix about anything with a VOM.


Jim Sparks has been in aviation for 30 years and is a licensed A&P. He is the manager of aviation maintenance for a private company with a fleet including light single engine aircraft, helicopters, and several types of business jets. He can be reached at sparks-jim@sbcglobal.net.

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