This piece originally ran in Vic’s Checkpoints column in the August 2022 issue of EAA Sport Aviation magazine.

I’m thinking that the loose jam nut plague might be under control, as we rarely see one monthly now. Compare that to multiple instances on several aircraft weekly just a few short years ago. I don’t doubt there are still some out there, and I’d still wager I could find a dozen or more in short order just by walking the flightline at EAA AirVenture Oshkosh and snooping around. I think the campaign worked, as we often hear comments such as “I checked the jam nuts” when customers are dropping off their aircraft for maintenance.

We are seeing some other repeat maintenance issues across the fleet, and I’d like to highlight a couple. These would be the top issues that owners/pilots can address. Some may require corrective action, and some may just require a regular check to see if any action is necessary.

The first one has to do with emergency locator transmitters (ELTs). FAR 91.201 covers the requirements for ELTs, and you should familiarize yourself with it, even if you rent an airplane. I am aware of checkrides and air show participation being stopped due to ELT requirements not being met. I will focus on the three key requirements: location, testing, and batteries.

For you builders, the regulation states that the ELT should be affixed to the airplane as far aft as possible. We see many of them installed in the cockpit, so that is the first no-no.

The next requirement is that every 12 months the ELT must be inspected for proper installation, battery corrosion, operation of the controls, and the presence of a sufficient signal radiated from its antenna. We have seen some ELTs whose batteries have corroded to the point that they have leaked outside of the ELT and caused major corrosion to the aircraft structure.

There are two types of ELTs. The older ones broadcast only on 121.5 MHz, which is in the aviation band. The newer 406 MHz ELTs broadcast on a protected international distress frequency monitored by satellites. Most of us older pilots were trained on the analog 121.5 MHz ELTs, and the test was to activate the switch during the first five minutes of any hour and listen on an aviation radio for no longer than three audible beeps.

The digital 406 MHz should only be tested in accordance with the manufacturer’s instructions, as many of them emit various tones to indicate a pass/fail test. The test should be limited to less than 30 seconds. This will preclude the satellites from receiving a signal from the 406 MHz beacon when it is activated. If the selection to the “ON” position is minimized to 30 seconds or less, there is sufficient time protection to prevent crossing the 50-second time threshold for activating the 406 MHz locator signal. No airborne tests of either type of ELT are allowed.

The last item has to do with the battery. Again, FAR 91.207 provides the guidance. Whenever the transmitter has been in use for more than a cumulative hour, or whenever the battery has reached 50 percent of its useful life, it must be replaced. Most ELTs that require a specific battery usually have a replacement date stamped on the battery and come with a decal to be affixed to the outside of the unit. Some ELTs use D cell batteries. For those, look at the expiration date on the battery and use 50 percent of that for the replacement requirement.

Here’s why we see the lowly ELT causing us so many problems. First, the replacement date of the battery must be marked on the outside of the transmitter and entered into the aircraft records. Less than half of the amateur-built aircraft we look at meet this requirement. The annual testing requirement should also be entered into the logbook. We make sure this is completed during the annual/condition inspection. However, here’s where it starts to go awry, especially for nonbuilder owners.

Rarely do the battery expiration and annual ELT testing coincide. Some batteries are good for 18 months, which puts them on the half cycle, and others are good for five years, which makes them easy to overlook. Some of the ELT batteries are expensive, so it doesn’t make sense to change them out six months early at the condition inspection. The expiration date entry is made in the logbook, and the owner is reminded, but it is often forgotten about. If batteries are due within a couple of months post condition inspection, we will change them, if available. Supply chain problems have been interesting in this area lately.

If the ELT has a control panel installed on the instrument panel, don’t forget that it has a battery in it as well. We have even seen these installed without a battery in them. Usually, that battery has a 10-year life, but it might make sense to change it at the 50 percent useful life as well.