John A. Landry wrote:
Greetings all,

I know this must've been discussed here before, but I couldn't find anything
definitive one way or the other when searching with Google.

A friend who's starting an amateur-built experimental aircraft project
recently emailed me to ask if there's a list of the *minimum* required
instruments he must have installed in order to obtain an airworthiness
certificate.
snip

I thought the minimums were something like:
Tachometer (1 per engine)
Oil pressure
Mag compass
Altimeter
Temperature (for liquid-cooled)
Oil temp (for air-cooled engines
Fuel quantity (1 per tank)
Lights (anticollision)
Airspeed
Manifold pressure (if constant speed prop)
ELT
Seat belts