14 CFR 25.1141 - Powerplant controls: general.
(a) Each control must be located so that it cannot be inadvertently operated by persons entering, leaving, or moving normally in, the cockpit.
(b) Each flexible control must be approved or must be shown to be suitable for the particular application.
(c) Each control must have sufficient strength and rigidity to withstand operating loads without failure and without excessive deflection.
(d) Each control must be able to maintain any set position without constant attention by flight crewmembers and without creep due to control loads or vibration.
(e) The portion of each powerplant control located in a designated fire zone that is required to be operated in the event of fire must be at least fire resistant.
(f) For powerplant valve controls located in the flight deck there must be a means:
(1) For the flightcrew to select each intended position or function of the valve; and
(2) To indicate to the flightcrew:
(i) The selected position or function of the valve; and
(ii) When the valve has not responded as intended to the selected position or function.