title-14-part-33-sec33-73

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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§ 33.75

thrust response must occur from a sta-
bilized static condition using only the
bleed air and accessories loads nec-
essary to run the engine. This takeoff
rating is specified by the applicant and
need not include thrust augmentation.

[Amdt. 33–1, 36 FR 5493, Mar. 24, 1971]

§ 33.74

Continued rotation.

If any of the engine main rotating

systems continue to rotate after the
engine is shutdown for any reason
while in flight, and if means to prevent
that continued rotation are not pro-
vided, then any continued rotation dur-
ing the maximum period of flight, and
in the flight conditions expected to
occur with that engine inoperative,
may not result in any condition de-
scribed in § 33.75(g)(2)(i) through (vi) of
this part.

[Amdt. 33–24, 72 FR 50867, Sept. 4, 2007]

§ 33.75

Safety analysis.

(a) (1) The applicant must analyze

the engine, including the control sys-
tem, to assess the likely consequences
of all failures that can reasonably be
expected to occur. This analysis will
take into account, if applicable:

(i) Aircraft-level devices and proce-

dures assumed to be associated with a
typical installation. Such assumptions
must be stated in the analysis.

(ii) Consequential secondary failures

and latent failures.

(iii) Multiple failures referred to in

paragraph (d) of this section or that re-
sult in the hazardous engine effects de-
fined in paragraph (g)(2) of this section.

(2) The applicant must summarize

those failures that could result in
major engine effects or hazardous en-
gine effects, as defined in paragraph (g)
of this section, and estimate the prob-
ability of occurrence of those effects.
Any engine part the failure of which
could reasonably result in a hazardous
engine effect must be clearly identified
in this summary.

(3) The applicant must show that

hazardous engine effects are predicted
to occur at a rate not in excess of that
defined as extremely remote (prob-
ability range of 10

to 10

per engine

flight hour). Since the estimated prob-
ability for individual failures may be
insufficiently precise to enable the ap-

plicant to assess the total rate for haz-
ardous engine effects, compliance may
be shown by demonstrating that the
probability of a hazardous engine effect
arising from an individual failure can
be predicted to be not greater than 10

per engine flight hour. In dealing with
probabilities of this low order of mag-
nitude, absolute proof is not possible,
and compliance may be shown by reli-
ance on engineering judgment and pre-
vious experience combined with sound
design and test philosophies.

(4) The applicant must show that

major engine effects are predicted to
occur at a rate not in excess of that de-
fined as remote (probability range of
10

to 10

per engine flight hour).

(b) The FAA may require that any as-

sumption as to the effects of failures
and likely combination of failures be
verified by test.

gle elements cannot be sensibly esti-
mated in numerical terms. If the fail-
ure of such elements is likely to result
in hazardous engine effects, then com-
pliance may be shown by reliance on
the prescribed integrity requirements
of §§ 33.15, 33.27, and 33.70 as applicable.
These instances must be stated in the
safety analysis.

(d) If reliance is placed on a safety

system to prevent a failure from pro-
gressing to hazardous engine effects,
the possibility of a safety system fail-
ure in combination with a basic engine
failure must be included in the anal-
ysis. Such a safety system may include
safety devices, instrumentation, early
warning devices, maintenance checks,
and other similar equipment or proce-
dures. If items of a safety system are
outside the control of the engine manu-
facturer, the assumptions of the safety
analysis with respect to the reliability
of these parts must be clearly stated in
the analysis and identified in the in-
stallation instructions under § 33.5 of
this part.

(e) If the safety analysis depends on

one or more of the following items,
those items must be identified in the
analysis and appropriately substan-
tiated.

(1) Maintenance actions being carried

out at stated intervals. This includes
the verification of the serviceability of