Encoding Altimeter Use.
Can an Encoding Altimeter be installed as the primary Altimeter (Pilot's) if the Encoder portion of it has been disabled or has not been wired to the Transponder?
ANSWER: No avionics component can be installed in a U.S. registered aircraft unless that component was produced under a production approval, and the data used to install and/or alter that components installation is FAA approved. Having said that, I refer you to - FAR 91.215 ATC transponder and altitude reporting equipment and use - for the operational requirements without an encoding altimeter.
The person who asked this question did further research and found a document published by the FAA that addresses this subject in detail. The document is called a Flight Standards Information Bulletin for Airworthiness. You can download a copy by clicking this link FSAW-97-02
I would like to thank her for sharing this information, and I'm sure that other users of this site will find it quite useful in addressing this subject.
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