[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR33.76]
[Page 781-784]
TITLE 14--AERONAUTICS AND SPACE
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
PART 33_AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES--Table of Contents
Subpart E_Design and Construction; Turbine Aircraft Engines
Sec. 33.76 Bird ingestion.
(a) General. Compliance with paragraphs (b) and (c) of this section
shall be in accordance with the following:
(1) All ingestion tests shall be conducted with the engine
stabilized at no less than 100-percent takeoff power or thrust, for test
day ambient conditions prior to the ingestion. In addition, the
demonstration of compliance must account for engine operation at sea
level takeoff conditions on the hottest day that a minimum engine can
achieve maximum rated takeoff thrust or power.
(2) The engine inlet throat area as used in this section to
determine the bird quantity and weights will be established by the
applicant and identified as a limitation in the installation
instructions required under Sec. 33.5.
(3) The impact to the front of the engine from the single large bird
and the single largest medium bird which can enter the inlet must be
evaluated. It must be shown that the associated components when struck
under the conditions prescribed in paragraphs (b) or (c) of this
section, as applicable, will not affect the engine to the extent that it
cannot comply with the requirements of paragraphs (b)(3) and (c)(6) of
this section.
(4) For an engine that incorporates an inlet protection device,
compliance with this section shall be established
[[Page 782]]
with the device functioning. The engine approval will be endorsed to
show that compliance with the requirements has been established with the
device functioning.
(5) Objects that are accepted by the Administrator may be
substituted for birds when conducting the bird ingestion tests required
by paragraphs (b) and (c) of this section.
(6) If compliance with the requirements of this section is not
established, the engine type certification documentation will show that
the engine shall be limited to aircraft installations in which it is
shown that a bird cannot strike the engine, or be ingested into the
engine, or adversely restrict airflow into the engine.
(b) Large birds. Compliance with the large bird ingestion
requirements shall be in accordance with the following:
(1) The large bird ingestion test shall be conducted using one bird
of a weight determined from Table 1 aimed at the most critical exposed
location on the first stage rotor blades and ingested at a bird speed of
200-knots for engines to be installed on airplanes, or the maximum
airspeed for normal rotorcraft flight operations for engines to be
installed on rotorcraft.
(2) Power lever movement is not permitted within 15 seconds
following ingestion of the large bird.
(3) Ingestion of a single large bird tested under the conditions
prescribed in this section may not cause the engine to:
(i) Catch fire;
(ii) Release hazardous fragments through the engine casing;
(iii) Generate loads greater than those ultimate loads specified
under Sec. 33.23(a); or
(iv) Lose the ability to be shut down.
(4) Compliance with the large bird ingestion requirements of this
paragraph may be shown by demonstrating that the requirements of Sec.
33.94(a) constitute a more severe demonstration of blade containment and
rotor unbalance than the requirements of this paragraph.
Table 1 to Sec. 33.76--Large Bird Weight Requirements
------------------------------------------------------------------------
Engine Inlet Throat Area (A)--Square-
meters (square-inches) Bird weight kg. (lb.)
------------------------------------------------------------------------
1.35 (2,092) A................. 1.85 (4.07) minimum, unless
a smaller bird is
determined to be a more
severe demonstration.
1.35 (2,092)<= A< 3.90 (6,045)............ 2.75 (6.05)
3.90 (6,045)<= A.......................... 3.65 (8.03)
------------------------------------------------------------------------
(c) Small and medium birds. Compliance with the small and medium
bird ingestion requirements shall be in accordance with the following:
(1) Analysis or component test, or both, acceptable to the
Administrator, shall be conducted to determine the critical ingestion
parameters affecting power loss and damage. Critical ingestion
parameters shall include, but are not limited to, the effects of bird
speed, critical target location, and first stage rotor speed. The
critical bird ingestion speed should reflect the most critical condition
within the range of airspeeds used for normal flight operations up to
1,500 feet above ground level, but not less than V1 minimum
for airplanes.
(2) Medium bird engine tests shall be conducted so as to simulate a
flock encounter, and will use the bird weights and quantities specified
in Table 2. When only one bird is specified, that bird will be aimed at
the engine core primary flow path; the other critical locations on the
engine face area must be addressed, as necessary, by appropriate tests
or analysis, or both. When two or more birds are specified in Table 2,
the largest of those birds must be aimed at the engine core primary flow
path, and a second bird must be aimed at the most critical exposed
location on the first stage rotor blades. Any remaining birds must be
evenly distributed over the engine face area.
(3) In addition, except for rotorcraft engines, it must also be
substantiated by appropriate tests or analysis or both, that when the
full fan assembly is subjected to the ingestion of the quantity and
weights of bird from Table 3, aimed at the fan assembly's most critical
location outboard of the primary core flowpath, and in accordance with
the applicable test conditions of this paragraph, that the engine
[[Page 783]]
can comply with the acceptance criteria of this paragraph.
(4) A small bird ingestion test is not required if the prescribed
number of medium birds pass into the engine rotor blades during the
medium bird test.
(5) Small bird ingestion tests shall be conducted so as to simulate
a flock encounter using one 85 gram (0.187 lb.) bird for each 0.032
square-meter (49.6 square-inches) of inlet area, or fraction thereof, up
to a maximum of 16 birds. The birds will be aimed so as to account for
any critical exposed locations on the first stage rotor blades, with any
remaining birds evenly distributed over the engine face area.
(6) Ingestion of small and medium birds tested under the conditions
prescribed in this paragraph may not cause any of the following:
(i) More than a sustained 25-percent power or thrust loss;
(ii) The engine to be shut down during the required run-on
demonstration prescribed in paragraphs (c)(7) or (c)(8) of this section;
(iii) The conditions defined in paragraph (b)(3) of this section.
(iv) Unacceptable deterioration of engine handling characteristics.
(7) Except for rotorcraft engines, the following test schedule shall
be used:
(i) Ingestion so as to simulate a flock encounter, with
approximately 1 second elapsed time from the moment of the first bird
ingestion to the last.
(ii) Followed by 2 minutes without power lever movement after the
ingestion.
(iii) Followed by 3 minutes at 75-percent of the test condition.
(iv) Followed by 6 minutes at 60-percent of the test condition.
(v) Followed by 6 minutes at 40-percent of the test condition.
(vi) Followed by 1 minute at approach idle.
(vii) Followed by 2 minutes at 75-percent of the test condition.
(viii) Followed by stabilizing at idle and engine shut down.
(ix) The durations specified are times at the defined conditions
with the power being changed between each condition in less than 10
seconds.
(8) For rotorcraft engines, the following test schedule shall be
used:
(i) Ingestion so as to simulate a flock encounter within
approximately 1 second elapsed time between the first ingestion and the
last.
(ii) Followed by 3 minutes at 75-percent of the test condition.
(iii) Followed by 90 seconds at descent flight idle.
(iv) Followed by 30 seconds at 75-percent of the test condition.
(v) Followed by stabilizing at idle and engine shut down.
(vi) The durations specified are times at the defined conditions
with the power being changed between each condition in less than 10
seconds.
(9) Engines intended for use in multi-engine rotorcraft are not
required to comply with the medium bird ingestion portion of this
section, providing that the appropriate type certificate documentation
is so endorsed.
(10) If any engine operating limit(s) is exceeded during the initial
2 minutes without power lever movement, as provided by paragraph
(c)(7)(ii) of this section, then it shall be established that the limit
exceedence will not result in an unsafe condition.
Table 2 to Sec. 33.76--Medium Flocking Bird Weight and Quantity
Requirements
------------------------------------------------------------------------
Engine Inlet Throat Area (A)-- Bird weight kg.
Square-meters (square-inches) Bird quantity (lb.)
------------------------------------------------------------------------
0.05 (77.5) A........ none.............. ..................
0.05 (77.5)<= A <0.10 (155)..... 1................. 0.35 (0.77)
0.10 (155)<= A <0.20 (310)...... 1................. 0.45 (0.99)
0.20 (310)<= A <0.40 (620)...... 2................. 0.45 (0.99)
0.40 (620)<= A <0.60 (930)...... 2................. 0.70 (1.54)
0.60 (930)<= A <1.00 (1,550).... 3................. 0.70 (1.54)
1.00 (1,550)<= A <1.35 (2,092).. 4................. 0.70 (1.54)
1.35 (2,092)<= A <1.70 (2,635).. 1................. 1.15 (2.53)
plus 3............ 0.70 (1.54)
1.70 (2,635)<= A <2.10 (3,255).. 1................. 1.15 (2.53)
plus 4............ 0.70 (1.54)
2.10 (3,255)<= A <2.50 (3,875).. 1................. 1.15 (2.53)
plus 5............ 0.70 (1.54)
2.50 (3,875)<= A <3.90 (6045)... 1................. 1.15 (2.53)
plus 6............ 0.70 (1.54)
3.90 (6045)<= A <4.50 (6975).... 3................. 1.15 (2.53)
4.50 (6975)<= A................. 4................. 1.15 (2.53)
------------------------------------------------------------------------
Table 3 to Sec. 33.76--Additional Integrity Assessment
------------------------------------------------------------------------
Engine Inlet Throat Area (A)-- Bird weight kg.
square-meters (square-inches) Bird quantity (lb.)
------------------------------------------------------------------------
1.35 (2,092) A....... none.............. ..................
1.35 (2,092)<= A <2.90 (4,495).. 1................. 1.15 (2.53)
2.90 (4,495)<= A <3.90 (6,045).. 2................. 1.15 (2.53)
3.90 (6,045)<= A................ 1................. 1.15 (2.53)
plus 6............ 0.70 (1.54)
------------------------------------------------------------------------
[[Page 784]]
[Doc. No. FAA-1998-4815, 65 FR 55854, Sept. 14, 2000, as amended by
Amdt. 33-20, 68 FR 75391, Dec. 31, 2003]