489 

Federal Aviation Administration, DOT 

§ 25.1165 

(b) Each intermediate position of the 

mixture controls that corresponds to a 
normal operating setting must be iden-
tifiable by feel and sight. 

(c) The mixture controls must be ac-

cessible to both pilots. However, if 
there is a separate flight engineer sta-
tion with a control panel, the controls 
need be accessible only to the flight en-
gineer. 

§ 25.1149

Propeller speed and pitch 

controls. 

(a) There must be a separate pro-

peller speed and pitch control for each 
propeller. 

(b) The controls must be grouped and 

arranged to allow— 

(1) Separate control of each pro-

peller; and 

(2) Simultaneous control of all pro-

pellers. 

(c) The controls must allow synchro-

nization of all propellers. 

(d) The propeller speed and pitch con-

trols must be to the right of, and at 
least one inch below, the pilot’s throt-
tle controls. 

§ 25.1153

Propeller feathering controls. 

(a) There must be a separate pro-

peller feathering control for each pro-
peller. The control must have means to 
prevent its inadvertent operation. 

(b) If feathering is accomplished by 

movement of the propeller pitch or 
speed control lever, there must be 
means to prevent the inadvertent 
movement of this lever to the feath-
ering position during normal oper-
ation. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–11, 32 FR 6913, May 5, 
1967] 

§ 25.1155

Reverse thrust and propeller 

pitch settings below the flight re-
gime. 

Each control for reverse thrust and 

for propeller pitch settings below the 
flight regime must have means to pre-
vent its inadvertent operation. The 
means must have a positive lock or 
stop at the flight idle position and 
must require a separate and distinct 
operation by the crew to displace the 
control from the flight regime (forward 

thrust regime for turbojet powered air-
planes). 

[Amdt. 25–11, 32 FR 6913, May 5, 1967] 

§ 25.1157

Carburetor air temperature 

controls. 

There must be a separate carburetor 

air temperature control for each en-
gine. 

§ 25.1159

Supercharger controls. 

Each supercharger control must be 

accessible to the pilots or, if there is a 
separate flight engineer station with a 
control panel, to the flight engineer. 

§ 25.1161

Fuel jettisoning system con-

trols. 

Each fuel jettisoning system control 

must have guards to prevent inad-
vertent operation. No control may be 
near any fire extinguisher control or 
other control used to combat fire. 

§ 25.1163

Powerplant accessories. 

(a) Each engine mounted accessory 

must— 

(1) Be approved for mounting on the 

engine involved; 

(2) Use the provisions on the engine 

for mounting; and 

(3) Be sealed to prevent contamina-

tion of the engine oil system and the 
accessory system. 

(b) Electrical equipment subject to 

arcing or sparking must be installed to 
minimize the probability of contact 
with any flammable fluids or vapors 
that might be present in a free state. 

(c) If continued rotation of an engine- 

driven cabin supercharger or of any re-
mote accessory driven by the engine is 
hazardous if malfunctioning occurs, 
there must be means to prevent rota-
tion without interfering with the con-
tinued operation of the engine. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–57, 49 FR 6849, Feb. 23, 
1984] 

§ 25.1165

Engine ignition systems. 

(a) Each battery ignition system 

must be supplemented by a generator 
that is automatically available as an 
alternate source of electrical energy to 
allow continued engine operation if 
any battery becomes depleted. 

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