870
14 CFR Ch. I (1–1–14 Edition)
§ 33.77
[Doc. No. FAA–1998–4815, 65 FR 55854, Sept.
14, 2000, as amended by Amdt. 33–20, 68 FR
75391, Dec. 31, 2003; Amdt. 33–24, 72 FR 50868,
Sept. 4, 2007; Amdt. 33–23, 72 FR 58974, Oct. 17,
2007]
§ 33.77
Foreign object ingestion—ice.
(a)–(b) [Reserved]
(c) Ingestion of ice under the condi-
tions of paragraph (e) of this section
may not—
(1) Cause a sustained power or thrust
loss; or
(2) Require the engine to be shut-
down.
(d) For an engine that incorporates a
protection device, compliance with this
section need not be demonstrated with
respect to foreign objects to be in-
gested under the conditions prescribed
in paragraph (e) of this section if it is
shown that—
(1) Such foreign objects are of a size
that will not pass through the protec-
tive device;
(2) The protective device will with-
stand the impact of the foreign objects;
and
(3) The foreign object, or objects,
stopped by the protective device will
not obstruct the flow of induction air
into the engine with a resultant sus-
tained reduction in power or thrust
greater than those values required by
paragraph (c) of this section.
(e) Compliance with paragraph (c) of
this section must be shown by engine
test under the following ingestion con-
ditions:
(1) Ice quantity will be the maximum
accumulation on a typical inlet cowl
and engine face resulting from a 2-
minute delay in actuating the anti-
icing system; or a slab of ice which is
comparable in weight or thickness for
that size engine.
(2) The ingestion velocity will simu-
late ice being sucked into the engine
inlet.
(3) Engine operation will be max-
imum cruise power or thrust.
(4) The ingestion will simulate a con-
tinuous maximum icing encounter at
25 degrees Fahrenheit.
[Doc. No. 16919, 49 FR 6852, Feb. 23, 1984, as
amended by Amdt. 33–19, 63 FR 14798, Mar. 26,
1998; 63 FR 53278, Oct. 5, 1998; Amdt. 33–20, 65
FR 55856, Sept. 14, 2000]
§ 33.78
Rain and hail ingestion.
(a)
All engines. (1) The ingestion of
large hailstones (0.8 to 0.9 specific grav-
ity) at the maximum true air speed, up
to 15,000 feet (4,500 meters), associated
with a representative aircraft oper-
ating in rough air, with the engine at
maximum continuous power, may not
cause unacceptable mechanical damage
or unacceptable power or thrust loss
after the ingestion, or require the en-
gine to be shut down. One-half the
number of hailstones shall be aimed
randomly over the inlet face area and
the other half aimed at the critical
inlet face area. The hailstones shall be
ingested in a rapid sequence to simu-
late a hailstone encounter and the
number and size of the hailstones shall
be determined as follows:
(i) One 1-inch (25 millimeters) diame-
ter hailstone for engines with inlet
areas of not more than 100 square
inches (0.0645 square meters).
(ii) One 1-inch (25 millimeters) di-
ameter and one 2-inch (50 millimeters)
diameter hailstone for each 150 square
inches (0.0968 square meters) of inlet
area, or fraction thereof, for engines
with inlet areas of more than 100
square inches (0.0645 square meters).
(2) In addition to complying with
paragraph (a)(1) of this section and ex-
cept as provided in paragraph (b) of
this section, it must be shown that
each engine is capable of acceptable op-
eration throughout its specified oper-
ating envelope when subjected to sud-
den encounters with the certification
standard concentrations of rain and
hail, as defined in appendix B to this
part. Acceptable engine operation pre-
cludes flameout, run down, continued
or non-recoverable surge or stall, or
loss of acceleration and deceleration
capability, during any three minute
continuous period in rain and during
any 30 second continuous period in
hail. It must also be shown after the
ingestion that there is no unacceptable
mechanical damage, unacceptable
power or thrust loss, or other adverse
engine anomalies.
(b)
Engines for rotorcraft. As an alter-
native to the requirements specified in
paragraph (a)(2) of this section, for
rotorcraft turbine engines only, it
must be shown that each engine is ca-
pable of acceptable operation during
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