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717 

Federal Aviation Administration, DOT 

§ 33.71 

§ 33.70

Engine life-limited parts. 

By a procedure approved by the FAA, 

operating limitations must be estab-
lished which specify the maximum al-
lowable number of flight cycles for 
each engine life-limited part. Engine 
life-limited parts are rotor and major 
static structural parts whose primary 
failure is likely to result in a haz-
ardous engine effect. Typically, engine 
life-limited parts include, but are not 
limited to disks, spacers, hubs, shafts, 
high-pressure casings, and non-redun-
dant mount components. For the pur-
poses of this section, a hazardous en-
gine effect is any of the conditions list-
ed in § 33.75 of this part. The applicant 
will establish the integrity of each en-
gine life-limited part by: 

(a) An engineering plan that contains 

the steps required to ensure each en-
gine life-limited part is withdrawn 
from service at an approved life before 
hazardous engine effects can occur. 
These steps include validated analysis, 
test, or service experience which en-
sures that the combination of loads, 
material properties, environmental in-
fluences and operating conditions, in-
cluding the effects of other engine 
parts influencing these parameters, are 
sufficiently well known and predictable 
so that the operating limitations can 
be established and maintained for each 
engine life-limited part. Applicants 
must perform appropriate damage tol-
erance assessments to address the po-
tential for failure from material, man-
ufacturing, and service induced anoma-
lies within the approved life of the 
part. Applicants must publish a list of 
the life-limited engine parts and the 
approved life for each part in the Air-
worthiness Limitations Section of the 
Instructions for Continued Airworthi-
ness as required by § 33.4 of this part. 

(b) A manufacturing plan that identi-

fies the specific manufacturing con-
straints necessary to consistently 
produce each engine life-limited part 
with the attributes required by the en-
gineering plan. 

(c) A service management plan that 

defines in-service processes for mainte-
nance and the limitations to repair for 
each engine life-limited part that will 
maintain attributes consistent with 
those required by the engineering plan. 
These processes and limitations will 

become part of the Instructions for 
Continued Airworthiness. 

[Amdt. 33–22, 72 FR 50860, Sept. 4, 2007] 

§ 33.71

Lubrication system. 

(a) 

General.  Each lubrication system 

must function properly in the flight at-
titudes and atmospheric conditions in 
which an aircraft is expected to oper-
ate. 

(b) 

Oil strainer or filter. There must be 

an oil strainer or filter through which 
all of the engine oil flows. In addition: 

(1) Each strainer or filter required by 

this paragraph that has a bypass must 
be constructed and installed so that oil 
will flow at the normal rate through 
the rest of the system with the strainer 
or filter element completely blocked. 

(2) The type and degree of filtering 

necessary for protection of the engine 
oil system against foreign particles in 
the oil must be specified. The applicant 
must demonstrate that foreign par-
ticles passing through the specified fil-
tering means do not impair engine oil 
system functioning. 

(3) Each strainer or filter required by 

this paragraph must have the capacity 
(with respect to operating limitations 
established for the engine) to ensure 
that engine oil system functioning is 
not impaired with the oil contaminated 
to a degree (with respect to particle 
size and density) that is greater than 
that established for the engine in para-
graph (b)(2) of this section. 

(4) For each strainer or filter re-

quired by this paragraph, except the 
strainer or filter at the oil tank outlet, 
there must be means to indicate con-
tamination before it reaches the capac-
ity established in accordance with 
paragraph (b)(3) of this section. 

(5) Any filter bypass must be de-

signed and constructed so that the re-
lease of collected contaminants is 
minimized by appropriate location of 
the bypass to ensure that the collected 
contaminants are not in the bypass 
flow path. 

(6) Each strainer or filter required by 

this paragraph that has no bypass, ex-
cept the strainer or filter at an oil 
tank outlet or for a scavenge pump, 
must have provisions for connection 
with a warning means to warn the pilot 
of the occurance of contamination of 

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718 

14 CFR Ch. I (1–1–24 Edition) 

§ 33.72 

the screen before it reaches the capac-
ity established in accordance with 
paragraph (b)(3) of this section. 

(7) Each strainer or filter required by 

this paragraph must be accessible for 
draining and cleaning. 

(c) 

Oil tanks. (1) Each oil tank must 

have an expansion space of not less 
than 10 percent of the tank capacity. 

(2) It must be impossible to inadvert-

ently fill the oil tank expansion space. 

(3) Each recessed oil tank filler con-

nection that can retain any appreciable 
quantity of oil must have provision for 
fitting a drain. 

(4) Each oil tank cap must provide an 

oil-tight seal. For an applicant seeking 
eligibility for an engine to be installed 
on an airplane approved for ETOPS, 
the oil tank must be designed to pre-
vent a hazardous loss of oil due to an 
incorrectly installed oil tank cap. 

(5) Each oil tank filler must be 

marked with the word ‘‘oil.’’ 

(6) Each oil tank must be vented 

from the top part of the expansion 
space, with the vent so arranged that 
condensed water vapor that might 
freeze and obstruct the line cannot ac-
cumulate at any point. 

(7) There must be means to prevent 

entrance into the oil tank or into any 
oil tank outlet, of any object that 
might obstruct the flow of oil through 
the system. 

(8) There must be a shutoff valve at 

the outlet of each oil tank, unless the 
external portion of the oil system (in-
cluding oil tank supports) is fireproof. 

(9) Each unpressurized oil tank may 

not leak when subjected to a maximum 
operating temperature and an internal 
pressure of 5 p.s.i., and each pressurized 
oil tank must meet the requirements of 
§ 33.64. 

(10) Leaked or spilled oil may not ac-

cumulate between the tank and the re-
mainder of the engine. 

(11) Each oil tank must have an oil 

quantity indicator or provisions for 
one. 

(12) If the propeller feathering system 

depends on engine oil— 

(i) There must be means to trap an 

amount of oil in the tank if the supply 
becomes depleted due to failure of any 
part of the lubricating system other 
than the tank itself; 

(ii) The amount of trapped oil must 

be enough to accomplish the feathering 
opeation and must be available only to 
the feathering pump; and 

(iii) Provision must be made to pre-

vent sludge or other foreign matter 
from affecting the safe operation of the 
propeller feathering system. 

(d) 

Oil drains. A drain (or drains) 

must be provided to allow safe drainage 
of the oil system. Each drain must— 

(1) Be accessible; and 
(2) Have manual or automatic means 

for positive locking in the closed posi-
tion. 

(e) 

Oil radiators. Each oil radiator 

must withstand, without failure, any 
vibration, inertia, and oil pressure load 
to which it is subjected during the 
block tests. 

[Amdt. 33–6, 39 FR 35466, Oct. 1, 1974, as 
amended by Amdt. 33–10, 49 FR 6852, Feb. 23, 
1984; Amdt. 33–21, 72 FR 1877, Jan. 16, 2007; 
Amdt. 33–27, 73 FR 55437, Sept. 25, 2008; Amdt. 
33–27, 73 FR 57235, Oct. 2, 2008] 

§ 33.72

Hydraulic actuating systems. 

Each hydraulic actuating system 

must function properly under all condi-
tions in which the engine is expected to 
operate. Each filter or screen must be 
accessible for servicing and each tank 
must meet the design criteria of § 33.71. 

[Amdt. 33–6, 39 FR 35467, Oct. 1, 1974] 

§ 33.73

Power or thrust response. 

The design and construction of the 

engine must enable an increase— 

(a) From minimum to rated takeoff 

power or thrust with the maximum 
bleed air and power extraction to be 
permitted in an aircraft, without over-
temperature, surge, stall, or other det-
rimental factors occurring to the en-
gine whenever the power control lever 
is moved from the minimum to the 
maximum position in not more than 1 
second, except that the Administrator 
may allow additional time increments 
for different regimes of control oper-
ation requiring control scheduling; and 

(b) From the fixed minimum flight 

idle power lever position when pro-
vided, or if not provided, from not more 
than 15 percent of the rated takeoff 
power or thrust available to 95 percent 
rated takeoff power or thrust in not 
over 5 seconds. The 5-second power or 

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