title-14-part-33-sec33-96

737

Federal Aviation Administration, DOT

§ 33.96

§ 33.94

Blade containment and rotor

unbalance tests.

(a) Except as provided in paragraph

(b) of this section, it must be dem-
onstrated by engine tests that the en-
gine is capable of containing damage
without catching fire and without fail-
ure of its mounting attachments when
operated for at least 15 seconds, unless
the resulting engine damage induces a
self shutdown, after each of the fol-
lowing events:

(1) Failure of the most critical com-

pressor or fan blade while operating at
maximum permissible r.p.m. The blade
failure must occur at the outermost re-
tention groove or, for integrally-bladed
rotor discs, at least 80 percent of the
blade must fail.

(2) Failure of the most critical tur-

bine blade while operating at max-
imum permissible r.p.m. The blade fail-
ure must occur at the outermost reten-
tion groove or, for integrally-bladed
rotor discs, at least 80 percent of the
blade must fail. The most critical tur-
bine blade must be determined by con-
sidering turbine blade weight and the
strength of the adjacent turbine case
at case temperatures and pressures as-
sociated with operation at maximum
permissible r.p.m.

(b) Analysis based on rig testing,

component testing, or service experi-
ence may be substitute for one of the
engine tests prescribed in paragraphs
(a)(1) and (a)(2) of this section if—

(1) That test, of the two prescribed,

produces the least rotor unbalance; and

(2) The analysis is shown to be equiv-

alent to the test.

(Secs. 313(a), 601, and 603, Federal Aviation
Act of 1958 (49 U.S.C. 1354(a), 1421, and 1423);
and 49 U.S.C. 106(g) Revised, Pub. L. 97–449,
Jan. 12, 1983)

[Amdt. 33–10, 49 FR 6854, Feb. 23, 1984]

§ 33.95

Engine-propeller systems tests.

If the engine is designed to operate

with a propeller, the following tests
must be made with a representative
propeller installed by either including
the tests in the endurance run or oth-
erwise performing them in a manner
acceptable to the Administrator:

(a) Feathering operation: 25 cycles.

(b) Negative torque and thrust sys-

tem operation: 25 cycles from rated
maximum continuous power.

cycles from rated maximum contin-
uous power (if repeated decoupling and
recoupling in service is the intended
function of the device).

(d) Reverse thrust operation: 175 cy-

cles from the flight-idle position to full
reverse and 25 cycles at rated max-
imum continuous power from full for-
ward to full reverse thrust. At the end
of each cycle the propeller must be op-
erated in reverse pitch for a period of
30 seconds at the maximum rotational
speed and power specified by the appli-
cant for reverse pitch operation.

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as
amended by Amdt. 33–3, 32 FR 3737, Mar. 4,
1967]

§ 33.96

Engine tests in auxiliary power

unit (APU) mode.

If the engine is designed with a pro-

peller brake which will allow the pro-
peller to be brought to a stop while the
gas generator portion of the engine re-
mains in operation, and remain stopped
during operation of the engine as an
auxiliary power unit (‘‘APU mode’’), in
addition to the requirements of § 33.87,
the applicant must conduct the fol-
lowing tests:

(a) Ground locking: A total of 45

hours with the propeller brake engaged
in a manner which clearly dem-
onstrates its ability to function with-
out adverse effects on the complete en-
gine while the engine is operating in
the APU mode under the maximum
conditions of engine speed, torque,
temperature, air bleed, and power ex-
traction as specified by the applicant.

(b) Dynamic braking: A total of 400

application-release cycles of brake en-
gagements must be made in a manner
which clearly demonstrates its ability
to function without adverse effects on
the complete engine under the max-
imum conditions of engine accelera-
tion/deceleration rate, speed, torque,
and temperature as specified by the ap-
plicant. The propeller must be stopped
prior to brake release.

stops with the propeller brake engaged.

(d) The tests required by paragraphs

(a), (b), and (c) of this section must be

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14 CFR Ch. I (1–1–24 Edition)

§ 33.97

performed on the same engine, but this
engine need not be the same engine
used for the tests required by § 33.87.

(e) The tests required by paragraphs

(a), (b), and (c) of this section must be
followed by engine disassembly to the
extent necessary to show compliance
with the requirements of § 33.93(a) and
§ 33.93(b).

[Amdt. 33–11, 51 FR 10346, Mar. 25, 1986]

§ 33.97

Thrust reversers.

(a) If the engine incorporates a re-

verser, the endurance, calibration, op-
eration, and vibration tests prescribed
in this subpart must be run with the
reverser installed. In complying with
this section, the power control lever
must be moved from one extreme posi-
tion to the other in not more than one
second except, if regimes of control op-
erations are incorporated necessitating
scheduling of the power-control lever
motion in going from one extreme posi-
tion to the other, a longer period of
time is acceptable but not more than
three seconds. In addition, the test pre-
scribed in paragraph (b) of this section
must be made. This test may be sched-
uled as part of the endurance run.

(b) 175 reversals must be made from

flight-idle forward thrust to maximum
reverse thrust and 25 reversals must be
made from rated takeoff thrust to max-
imum reverse thrust. After each rever-
sal the reverser must be operated at
full reverse thrust for a period of one
minute, except that, in the case of a re-
verser intended for use only as a brak-
ing means on the ground, the reverser
need only be operated at full reverse
thrust for 30 seconds.

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as
amended by Amdt. 33–3, 32 FR 3737, Mar. 4,
1967; Amdt. No. 33–35, 87 FR 75711, Dec. 9,
2022; 88 FR 2813, Jan. 18, 2023]

§ 33.99

General conduct of block tests.

(a) Each applicant may, in making a

block test, use separate engines of
identical design and construction in
the vibration, calibration, endurance,
and operation tests, except that, if a
separate engine is used for the endur-
ance test it must be subjected to a cali-
bration check before starting the en-
durance test.

(b) Each applicant may service and

make minor repairs to the engine dur-
ing the block tests in accordance with
the service and maintenance instruc-
tions submitted in compliance with
§ 33.4. If the frequency of the service is
excessive, or the number of stops due
to engine malfunction is excessive, or a
major repair, or replacement of a part
is found necessary during the block
tests or as the result of findings from
the teardown inspection, the engine or
its parts must be subjected to any addi-
tional tests the Administrator finds
necessary.

testing facilities, including equipment
and competent personnel, to conduct
the block tests.

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as
amended by Amdt. 33–6, 39 FR 35470, Oct. 1,
1974; Amdt. 33–9, 45 FR 60181, Sept. 11, 1980]

Subpart G—Special Requirements:

Turbine Aircraft Engines

OURCE

: Docket No. FAA–2002–6717, 72 FR

1877, Jan. 16, 2007, unless otherwise noted.

§ 33.201

Design and test requirements

for Early ETOPS eligibility.

An applicant seeking type design ap-

proval for an engine to be installed on
a two-engine airplane approved for
ETOPS without the service experience
specified in part 25, appendix K, K25.2.1
of this chapter, must comply with the
following:

(a) The engine must be designed

using a design quality process accept-
able to the FAA, that ensures the de-
sign features of the engine minimize
the occurrence of failures, malfunc-
tions, defects, and maintenance errors
that could result in an IFSD, loss of
thrust control, or other power loss.

(b) The design features of the engine

must address problems shown to result
in an IFSD, loss of thrust control, or
other power loss in the applicant’s
other relevant type designs approved
within the past 10 years, to the extent
that adequate service data is available
within that 10-year period. An appli-
cant without adequate service data
must show experience with and knowl-
edge of problem mitigating design
practices equivalent to that gained