never mind somewhere to keep a flight manual!
Yeah that can be a problem! I was flying an MD500E helicopter the other day. The Flight Manual was certainly aboard, in the compartment under your heels. Accessible if you lift your feet up! I never said that aircraft are well thought out as to where manuals are stored in the cockpit.
When I approve a placard for the instrument panel which includes "refer to Flight Manual [Supplement]", it is my hope that the pilot has made themselves familiar with the referenced details
before they are airborne - that's part of the type familiarization whether you are checked out by someone, or check yourself out - in either case, you should be making yourself familiar. The placard just reminds you of that.
In my worst example of not reading a Flight Manual before flight, I was ferrying a new Cessna 303, and entering icing conditions, with all the deicing systems operating, to have a really bad - near fatal event related to icing. I later read in the Flight Manual that flight into known icing approval had been removed from the aircraft (it was to begin with) by an AD ,a d placard - the placard had not been installed. Thus my self checkout in the plane by cockpit and placard review had failed.
Read the FM
before you fly the plane!