Federal Aviation Administration, DOT

Section 33.87

compliance can be shown shall be substantiated and defined in the installation instructions required by Section 33.5.
[Doc. No. 28107, 61 FR 28433, June 4, 1996, as
amended by Amdt. 33-33, 77 FR 39624, July 5,
2012; 77 FR 58301, Sept. 20, 2012]

spaschal on DSK3GDR082PROD with CFR

Section 33.84

Engine overtorque test.

(a) If approval of a maximum engine
overtorque is sought for an engine incorporating a free power turbine, compliance with this section must be demonstrated by testing.
(1) The test may be run as part of the
endurance test requirement of Section 33.87.
Alternatively, tests may be performed
on a complete engine or equivalent
testing on individual groups of components.
(2) Upon conclusion of tests conducted to show compliance with this
section, each engine part or individual
groups of components must meet the
requirements of Section 33.93(a)(1) and (a)(2).
(b) The test conditions must be as
follows:
(1) A total of 15 minutes run at the
maximum engine overtorque to be approved. This may be done in separate
runs, each being of at least 21-2 minutes
duration.
(2) A power turbine rotational speed
equal to the highest speed at which the
maximum overtorque can occur in
service. The test speed may not be
more than the limit speed of take-off
or OEI ratings longer than 2 minutes.
(3) For engines incorporating a reduction gearbox, a gearbox oil temperature equal to the maximum temperature when the maximum engine overtorque could occur in service; and for
all other engines, an oil temperature
within the normal operating range.
(4) A turbine entry gas temperature
equal to the maximum steady state
temperature approved for use during
periods longer than 20 seconds when operating at conditions not associated
with 30-second or 2 minutes OEI ratings. The requirement to run the test
at the maximum approved steady state
temperature may be waived by the
FAA if the applicant can demonstrate
that other testing provides substantiation of the temperature effects when
considered in combination with the
other parameters identified in para-

graphs (b)(1), (b)(2) and (b)(3) of this
section.
[Doc. No. 2007-28502, 74 FR 45310, Sept. 2, 2009]

Section 33.85

Calibration tests.

(a) Each engine must be subjected to
those calibration tests necessary to establish its power characteristics and
the conditions for the endurance test
specified Section 33.87. The results of the
power characteristics calibration tests
form the basis for establishing the
characteristics of the engine over its
entire operating range of speeds, pressures, temperatures, and altitudes.
Power ratings are based upon standard
atmospheric
conditions
with
no
airbleed for aircraft services and with
only those accessories installed which
are essential for engine functioning.
(b) A power check at sea level conditions must be accomplished on the endurance test engine after the endurance test and any change in power
characteristics which occurs during the
endurance test must be determined.
Measurements taken during the final
portion of the endurance test may be
used in showing compliance with the
requirements of this paragraph.
(c) In showing compliance with this
section, each condition must stabilize
before measurements are taken, except
as permitted by paragraph (d) of this
section.
(d) In the case of engines having 30second OEI, and 2-minute OEI ratings,
measurements taken during the applicable endurance test prescribed in
Section 33.87(f) (1) through (8) may be used in
showing compliance with the requirements of this section for these OEI ratings.
[Doc. No. 3025, 29 FR 7453, June 10, 1964, as
amended by Amdt. 33-6, 39 FR 35468, Oct. 1,
1974; Amdt. 33-18, 61 FR 31328, June 19, 1996]

Section 33.87

Endurance test.

(a) General. Each engine must be subjected to an endurance test that includes a total of at least 150 hours of
operation and, depending upon the type
and contemplated use of the engine,
consists of one of the series of runs
specified in paragraphs (b) through (g)
of this section, as applicable. For engines tested under paragraphs (b), (c),

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