Noise from inside of altimeter

[Bavafa]

I had to pull one of my gauges out yesterday and as part of that, I had to pull my United 3" altimeter out. As I pulled it out of the panel, I hear some thing being lose in there like a small nut or washer and it moves around. Any body has open one out and are there any thing to look for if I was going to open it (dismantle it). Does it require special tools or?.?

It has been working without any issues, just not sure what is lose in there.

[Sparky]

Mehrdad,

I would highly recommend bringing it to a qualified instrument repair shop to have it checked out and/or repaired and calibrated.

However, you may be able to find out what is floating around in there by removing the fitting installed on the back of the unit and placing the unit face up and (gently) shaking the unit until the loose part falls out the open port. It may just be construction debris that found its way into your static line and then somehow got into the altimeter. If it is a screw, nut or other legitimate looking altimeter part I would bring it to a qualified shop to have it checked out, repaired, recalibrated, etc.

By the way, the static port on the back of the unit is open to the entire inside of the altimeter case. There is a gasket seal on the front face of the unit and an o-ring on the baro shaft to seal the front of the unit. Altitude is sensed by a sealed copper diaphram which is connected by gears directly to the dial indicator arms. Most of the screws and nuts inside the unit are just to hold the whole assembly together.

Good luck!