§ 121.307 – Engine instruments.
Unless the Administrator allows or requires different instrumentation for turbine engine powered airplanes to provide equivalent safety, no person may conduct any operation under this part without the following engine instruments:
(a) A carburetor air temperature indicator for each engine.
(b) A cylinder head temperature indicator for each air-cooled engine.
(c) A fuel pressure indicator for each engine.
(d) A fuel flowmeter or fuel mixture indicator for each engine not equipped with an automatic altitude mixture control.
(e) A means for indicating fuel quantity in each fuel tank to be used.
(f) A manifold pressure indicator for each engine.
(g) An oil pressure indicator for each engine.
(h) An oil quantity indicator for each oil tank when a transfer or separate oil reserve supply is used.
(i) An oil-in temperature indicator for each engine.
(j) A tachometer for each engine.
(k) An independent fuel pressure warning device for each engine or a master warning device for all engines with a means for isolating the individual warning circuits from the master warning device.
(l) A device for each reversible propeller, to indicate to the pilot when the propeller is in reverse pitch, that complies with the following:
(1) The device may be actuated at any point in the reversing cycle between the normal low pitch stop position and full reverse pitch, but it may not give an indication at or above the normal low pitch stop position.
(2) The source of indication must be actuated by the propeller blade angle or be directly responsive to it.