729 

Federal Aviation Administration, DOT 

§ 33.87 

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 op-
erating at conditions not associated 
with 30-second or 2 minutes OEI rat-
ings. 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 substan-
tiation 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] 

§ 33.85

Calibration tests. 

(a) Each engine must be subjected to 

those calibration tests necessary to es-
tablish its power characteristics and 
the conditions for the endurance test 
specified § 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, pres-
sures, 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 condi-

tions must be accomplished on the en-
durance test engine after the endur-
ance 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 30- 

second OEI, and 2-minute OEI ratings, 
measurements taken during the appli-
cable endurance test prescribed in 
§ 33.87(f) (1) through (8) may be used in 
showing compliance with the require-

ments of this section for these OEI rat-
ings. 

[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] 

§ 33.87

Endurance test. 

(a) 

General. Each engine must be sub-

jected to an endurance test that in-
cludes 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 en-
gines tested under paragraphs (b), (c), 
(d), (e) or (g) of this section, the pre-
scribed 6-hour test sequence must be 
conducted 25 times to complete the re-
quired 150 hours of operation. Engines 
for which the 30-second OEI and 2- 
minute OEI ratings are desired must be 
further tested under paragraph (f) of 
this section. The following test re-
quirements apply: 

(1) The runs must be made in the 

order found appropriate by the FAA for 
the particular engine being tested. 

(2) Any automatic engine control 

that is part of the engine must control 
the engine during the endurance test 
except for operations where automatic 
control is normally overridden by man-
ual control or where manual control is 
otherwise specified for a particular test 
run. 

(3) Except as provided in paragraph 

(a)(5) of this section, power or thrust, 
gas temperature, rotor shaft rotational 
speed, and, if limited, temperature of 
external surfaces of the engine must be 
at least 100 percent of the value associ-
ated with the particular engine oper-
ation being tested. More than one test 
may be run if all parameters cannot be 
held at the 100 percent level simulta-
neously. 

(4) The runs must be made using fuel, 

lubricants and hydraulic fluid which 
conform to the specifications specified 
in complying with § 33.7(c). 

(5) Maximum air bleed for engine and 

aircraft services must be used during 
at least one-fifth of the runs, except for 
the test required under paragraph (f) of 
this section, provided the validity of 
the test is not compromised. However, 
for these runs, the power or thrust or 
the rotor shaft rotational speed may be 

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