This weekend I was busy with many tasks, most of them small and not newsworthy – just things I want to get done ahead of an airworthiness inspection. However, one important thing I had not done, was test the ELT. To be honest, I was kind of scared of testing it, and had installed it a long time ago thinking I would one day figure out how to test the thing. In hindsight, I should have learned all about it back then and performed the test. I ended up with a couple of problems that took an annoyingly long time to solve.
Testing an ELT is tricky, because setting off a locator beacon can trigger search and rescue operations, so you want to make sure you understand the rules and regulations, and the operations of the unit. Unlike older ELTs, this one will transmit aircraft info including GPS coordinates to a satellite constellation. I started by reading the installation manual (I had read it before, but needed a refresh). The first thing was to register the unit with NOAA, which is compulsory before triggering the signal, so I went ahead and did that. Derek, if you are reading this – fyi, you are one a small group of emergency contacts. There are a set of tests that require equipment I don’t have, so I skipped that and moved to the ELT self-test.
The self does an internal system check, then broadcasts on 121.5 for two cycles, tests that it’s receiving Nav info, and sounds the buzzer. If anything is wrong during the test, the LED flashes and number of flashes indicates the error code. The annoying limitation on testing the device is that it’s only allowed during the first 5 minutes of each hour. That means if you have a problem, you really don’t have time to troubleshoot it before that time expires and you have to wait another hour to test if you have resolved the issue.
On my first attempt to run a self-test, I waited for the hour to strike, pushed the self-test button, and absolutely nothing happened. Hmm. I decided to take the unit out, remove the battery, and give it a more thorough inspection. Everything looked as it should, and I reinstalled the battery etc, still wondering why it wasn’t working. As soon as I plugged the battery into the receptacle on the circuit board, the LED lit up and it beeped. Then it kept beeping! I quickly consulted the manual and saw a warning that connecting the battery can sometimes activate the ELT. The fix is to turn it to “On” (activate it), then back to “Arm”. This quickly resolved the issue, but I still accidentally transmitted for a few seconds.
With that figured out, I reinstalled everything, waiting for the next hour, and performed the self test again. This time the unit beeped, and then gave a couple of different error codes. Hmm. Consulting the manual
I ended up pulling apart the D-sub connector and inspecting the wiring going into the ELT and buzzer. I discovered the buzzer power wire was in the wrong position, but everything else seemed to check out. I confirmed the correct wiring at the remote switch on the panel, and couldn’t find any other issues. I put it back together, waited for the right time and retested. Still an error.
After some online research, I discovered that while the ELT supports several different formats of data from the Nav system, when it’s programmed, it’s set for one format – it doesn’t dynamically switch between protocols and baud rates. With that info, I went into the avionics configuration and found there were dozens of different available formats that the G3X can output, and the one selected for the transponder was probably not the right one. I adjusted to the “Aviation” format, re-ran the self-test and happily the self-test passed!
Unfortunately the buzzer still didn’t sound, so I need to troubleshoot the buzzer. Next time I’m at the hangar I’ll test the buzzer manually with a battery to verify that it’s actually functional. If it is, then there is likely a problem with the wiring – perhaps a bad ground somehow – or the buzzer power is configured to come from another pin on the ELT. The least likely problem is the ELT itself not supplying power. I really hope that’s not the case, as I don’t want to have to replace the unit at this stage.
