TROUBLESHOOTING
Some Exceptions To The Rule It is rare, but sometimes there can be multiple paths causing the problem. In the situation above, say we found the broken battery at the buss, replaced it, tested the voltage going to the widget, and the operational test failed. We know that the electrical path is good, so we test the mechanical path and find a worn rod end at a control lever that was causing improper input to the widget. We replace the rod end and the system now works. It is rare, but it can happen. And then there’s that weird anomaly that can occur.
Maybe you’ve seen something like it – the problem just doesn’t seem to make sense. For example, the pilot reports that he is getting a flag on his attitude indicator, the transmission oil temp annunciator light is coming on intermittently and the copilot’s headset is inoperative. What the heck, for giggles and grins, let’s just say that the widget isn’t working either. Numerous circuit breakers are popping. You know that these different systems can’t possibly be tied together, yet they all occurred at the same time. Through your experience you also know that popping circuit breakers indicate shorts to ground. It takes some time, but through looking at the paths of influence for these different problems, you discover they all have wires running together in a wire bundle behind the copilot’s lower side panel. You remove the panel and see evidence of electrical arcing. You then discover that a screw that had been installed in the side panel at the last scheduled inspection had improperly been installed right next to the wire bundle. A few months of vibration and movement had caused it to chafe through a few wires, causing some wires to short to ground while causing minor damage to others (hence the odd indications). You replace the defective wires as needed and the problem is solved. These troubleshooting basics can be used to repair anything. It can work on your toaster, your motorcycle, your garage door opener – you name it, it if it broken and you follow the four-
step process, you can fix it! Heck, it could even work in a personal relationship. 1) Define the situation 2) Find the paths of influence 3) Test 4) Take corrective action In closing, I would highly recommend FlightSafety
International’s Principles of Troubleshooting course to anyone who wants to improve his or her troubleshooting skills. There is a lot more information covered in the class than in this overview including logic symbology, electrical schematics, and plenty of computer-based training exercises that track man-hours and cost for each troubleshooting scenario. After all, it’s better to practice troubleshooting and make mistakees on a computer simulation rather than making them on your company’s or customer’s helicopter! For more information, visit www.
flightsafety.com.
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June | July 2016
HelicopterMaintenanceMagazine.com 23 5/23/16 2:01 PM
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