538 

14 CFR Ch. I (1–1–24 Edition) 

§ 27.995 

which relative motion could exist must 
have provisions for flexibility. 

(c) Flexible hose must be approved. 
(d) Each flexible connection in fuel 

lines that may be under pressure or 
subjected to axial loading must use 
flexible hose assemblies. 

(e) No flexible hose that might be ad-

versely affected by high temperatures 
may be used where excessive tempera-
tures will exist during operation or 
after engine shutdown. 

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as 
amended by Amdt. 27–2, 33 FR 964, Jan. 26, 
1968] 

§ 27.995

Fuel valves. 

(a) There must be a positive, quick- 

acting valve to shut off fuel to each en-
gine individually. 

(b) The control for this valve must be 

within easy reach of appropriate crew-
members. 

(c) Where there is more than one 

source of fuel supply there must be 
means for independent feeding from 
each source. 

(d) No shutoff valve may be on the 

engine side of any firewall. 

§ 27.997

Fuel strainer or filter. 

There must be a fuel strainer or filter 

between the fuel tank outlet and the 
inlet of the first fuel system compo-
nent which is susceptible to fuel con-
tamination, including but not limited 
to the fuel metering device or an en-
gine positive displacement pump, 
whichever is nearer the fuel tank out-
let. This fuel strainer or filter must— 

(a) Be accessible for draining and 

cleaning and must incorporate a screen 
or element which is easily removable; 

(b) Have a sediment trap and drain 

except that it need not have a drain if 
the strainer or filter is easily remov-
able for drain purposes; 

(c) Be mounted so that its weight is 

not supported by the connecting lines 
or by the inlet or outlet connections of 
the strainer or filter itself, unless ade-
quate strength margins under all load-
ing conditions are provided in the lines 
and connections; and 

(d) Provide a means to remove from 

the fuel any contaminant which would 
jeopardize the flow of fuel through 
rotorcraft or engine fuel system com-
ponents required for proper rotorcraft 

fuel system or engine fuel system oper-
ation. 

[Amdt. 27–9, 39 FR 35461, Oct. 1, 1974, as 
amended by Amdt. 27–20, 49 FR 6849, Feb. 23, 
1984; Amdt. 27–23, 53 FR 34213, Sept. 2, 1988] 

§ 27.999

Fuel system drains. 

(a) There must be at least one acces-

sible drain at the lowest point in each 
fuel system to completely drain the 
system with the rotorcraft in any 
ground attitude to be expected in serv-
ice. 

(b) Each drain required by paragraph 

(a) of this section must— 

(1) Discharge clear of all parts of the 

rotorcraft; 

(2) Have manual or automatic means 

to assure positive closure in the off po-
sition; and 

(3) Have a drain valve— 
(i) That is readily accessible and 

which can be easily opened and closed; 
and 

(ii) That is either located or pro-

tected to prevent fuel spillage in the 
event of a landing with landing gear re-
tracted. 

[Doc. No. 574, 29 FR 15695, Nov. 24, 1964, as 
amended by Amdt. 27–11, 41 FR 55470, Dec. 20, 
1976; Amdt. 27–23, 53 FR 34213, Sept. 2, 1988] 

O

IL

S

YSTEM

 

§ 27.1011

Engines: General. 

(a) Each engine must have an inde-

pendent oil system that can supply it 
with an appropriate quantity of oil at a 
temperature not above that safe for 
continuous operation. 

(b) The usable oil capacity of each 

system may not be less than the prod-
uct of the endurance of the rotorcraft 
under critical operating conditions and 
the maximum oil consumption of the 
engine under the same conditions, plus 
a suitable margin to ensure adequate 
circulation and cooling. Instead of a ra-
tional analysis of endurance and con-
sumption, a usable oil capacity of one 
gallon for each 40 gallons of usable fuel 
may be used. 

(c) The oil cooling provisions for each 

engine must be able to maintain the oil 
inlet temperature to that engine at or 

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