Buggy Fuel Gauge

Shortly after calibrating the EI FL-2CA fuel gauge, I noticed that the level on the right tank would go to zero when I keyed the mic. Afterwards, it would slowly return to an accurate level. An annoying feature to say the least! So I asked around on the internet and found a couple of others with the same issues, but they've learned to deal with it.

I sent an email to EI Tech Support next. They replied, RF issues are probably the most difficult issue to tackle in an aircraft panel. The issue may be arising from one of a couple factors. Either there is a loose or bad ground, the cables for the radio are mismatched, the instrument has a failed filter the interface module has a failed component or some combination of two of these factors. We rarely see this issue, but when we have, nothing has failed in our instruments or interface modules. We also "over design" the product by putting several RF filters in place. We far, far exceed the RF susceptibility requirements set forth by the FAA. One quick method to determine if the issue lies within the instrument is to take some aluminum foil and wrap the pigtail of wires coming out of the back of the instrument and then try to key your mic. If there is a noticeable improvement, you may have an issue with a filter in the instrument. I would also make absolutely certain that you have solid grounds for your panel and the FL-2C.

I checked things over, and tried the shielding, but nothing changed. EI added, We recently had a customer with a Lancair have a similar issue. His issue was compounded by the fact that his aircraft was not metal, and neither was his panel. As a result, he had grounding issues all over his aircraft. Our engineers designed a special interface module for him, and it solved his problem completely. I would be willing to send you two of these new interface modules free of charge if you were able to get to the ones currently installed in your aircraft. Simply let me know where to ship them, and I'll send them off.

The new module solved the problem!! Many thanks to Tyler Speed of Electronics International for his great support.