pitot static

[rcoons]

I have a 72 7GCBC. The problem I'm having is air traffic is telling me my altitude differs from what I'm showing on my altimeter sometimes. Some days it's right on and next time it can be off by 500 ft. I have a blind encoder and narco transponder that checks out. The manual says to check the static system for leaks and blockage, problem is "where is the staic vent located?

Thanks

 

[jerrymjr]

On a wood spar 1972, the static boom is right with the pitot on the jury strut. On a ACA metal spar conversion, the static ports are just behind the back window on the side of the airplane...about the thrust line.

Typically an encoder uses static pressure...which would be the same source, normally. It only reads pressure altitude too.