Bad RPM gauge

My plane has been down a week with a bad RPM gauge. Every time they put in a new gauge it burns out. Has anyone else had a similar problem?

As a Cirrus Instructor I had this happen twice. Both times the factory said it was the second alt sending eroneous signals to the gauge. Have your service center check it out. At the time the alt light was giving me trouble as well so it may or may not be the source.

Chris Baker

My plane has been down a week with a bad RPM gauge. Every time they put in a new gauge it burns out. Has anyone else had a similar problem?

Jim,

It happened to me several months ago in Scottsdale. On a full power run-up it showed >500 RPM low. I did a takeoff roll planning to abort, but it came right back up to normal, and so I continued. Had full power all along. No problems since.

My plane has been down a week with a bad RPM gauge. Every time they put in a new gauge it burns out. Has anyone else had a similar problem?

I believe (not sure) that the RPM wires are passed through a Molex connector in the engine baffling (the vertical metal about 8" forward of the firewall). I had to have a Molex connector in my plane, the one for fuel-flow, replaced due to a faulty connection. The connector would vibrate and send extra pulses, making my fuel-flow read high and be jerky. Perhaps the same thing has happened to the Molex connector in your plane for your RPM gauge and the RPM gauge doesn’t like sudden jolts that a connection being made and broken quickly would create. Btw, my fuel-flow sensor died at the same time. Perhaps it didn’t like the oonnection being made and broken repeatedly.

I assume your system voltage appears normal and you have no warning lights on and nothing else is being burned out.

If you have access to a battery-powered digital storage scope, I’d hook it up to the power bus and set it to trigger on voltage excursions out of the norm. I’ve been meaning to do this to my plane to see if during engine start or shutdown there are any nasty spikes.

Btw, the Arnav guys said that their unit is designed to take up to 600V spikes. I think they are designing to some FAA standard, so this may be what all the avionics are designed to.

Let us know what it turns out to be.

My service shop, with Cirrus’s agreement, replaced the Molex connector for the fuel-flow line in my plane with something they use in Money’s which are supposed to be fairly reliable.

My plane has been down a week with a bad RPM gauge. Every time they put in a new gauge it burns out. Has anyone else had a similar problem?