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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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730 

14 CFR Ch. I (1–1–24 Edition) 

§ 33.87 

less than 100 percent of the value asso-
ciated with the particular operation 
being tested if the FAA finds that the 
validity of the endurance test is not 
compromised. 

(6) Each accessory drive and mount-

ing attachment must be loaded in ac-
cordance with paragraphs (a)(6)(i) and 
(ii) of this section, except as permitted 
by paragraph (a)(6)(iii) of this section 
for the test required under paragraph 
(f) of this section. 

(i) The load imposed by each acces-

sory used only for aircraft service must 
be the limit load specified by the appli-
cant for the engine drive and attach-
ment point during rated maximum con-
tinuous power or thrust and higher 
output. 

(ii) The endurance test of any acces-

sory drive and mounting attachment 
under load may be accomplished on a 
separate rig if the validity of the test 
is confirmed by an approved analysis. 

(iii) The applicant is not required to 

load the accessory drives and mounting 
attachments when running the tests 
under paragraphs (f)(1) through (f)(8) of 
this section if the applicant can sub-
stantiate that there is no significant 
effect on the durability of any acces-
sory drive or engine component. How-
ever, the applicant must add the equiv-
alent engine output power extraction 
from the power turbine rotor assembly 
to the engine shaft output. 

(7) During the runs at any rated 

power or thrust the gas temperature 
and the oil inlet temperature must be 
maintained at the limiting tempera-
ture except where the test periods are 
not longer than 5 minutes and do not 
allow stabilization. At least one run 
must be made with fuel, oil, and hy-
draulic fluid at the minimum pressure 
limit and at least one run must be 
made with fuel, oil, and hydraulic fluid 
at the maximum pressure limit with 
fluid temperature reduced as necessary 
to allow maximum pressure to be at-
tained. 

(8) If the number of occurrences of ei-

ther transient rotor shaft overspeed, 
transient gas overtemperature or tran-
sient engine overtorque is limited, that 
number of the accelerations required 
by paragraphs (b) through (g) of this 
section must be made at the limiting 
overspeed, overtemperature or over-

torque. If the number of occurrences is 
not limited, half the required accelera-
tions must be made at the limiting 
overspeed, overtemperature or over-
torque. 

(9) For each engine type certificated 

for use on supersonic aircraft the fol-
lowing additional test requirements 
apply: 

(i) To change the thrust setting, the 

power control lever must be moved 
from the initial position to the final 
position in not more than one second 
except for movements into the fuel 
burning thrust augmentor augmenta-
tion position if additional time to con-
firm ignition is necessary. 

(ii) During the runs at any rated aug-

mented thrust the hydraulic fluid tem-
perature must be maintained at the 
limiting temperature except where the 
test periods are not long enough to 
allow stabilization. 

(iii) During the simulated supersonic 

runs the fuel temperature and induc-
tion air temperature may not be less 
than the limiting temperature. 

(iv) The endurance test must be con-

ducted with the fuel burning thrust 
augmentor installed, with the primary 
and secondary exhaust nozzles in-
stalled, and with the variable area ex-
haust nozzles operated during each run 
according to the methods specified in 
complying with § 33.5(b). 

(v) During the runs at thrust settings 

for maximum continuous thrust and 
percentages thereof, the engine must 
be operated with the inlet air distor-
tion at the limit for those thrust set-
tings. 

(b) 

Engines other than certain rotor-

craft engines. For each engine except a 
rotorcraft engine for which a rating is 
desired under paragraph (c), (d), or (e) 
of this section, the applicant must con-
duct the following runs: 

(1) 

Takeoff and idling. One hour of al-

ternate five-minute periods at rated 
takeoff power or thrust and at idling 
power or thrust. The developed powers 
or thrusts at takeoff and idling condi-
tions and their corresponding rotor 
speed and gas temperature conditions 
must be as established by the power 
control in accordance with the sched-
ule established by the applicant. The 
applicant may, during any one period, 
manually control the rotor speed, 

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731 

Federal Aviation Administration, DOT 

§ 33.87 

power, or thrust while taking data to 
check performance. For engines with 
augmented takeoff power ratings that 
involve increases in turbine inlet tem-
perature, rotor speed, or shaft power, 
this period of running at takeoff must 
be at the augmented rating. For en-
gines with augmented takeoff power 
ratings that do not materially increase 
operating severity, the amount of run-
ning conducted at the augmented rat-
ing is determined by the FAA. In 
changing the power setting after each 
period, the power-control lever must be 
moved in the manner prescribed in 
paragraph (b)(5) of this section. 

(2) 

Rated maximum continuous and 

takeoff power or thrust. Thirty minutes 
at— 

(i) Rated maximum continuous power 

or thrust during fifteen of the twenty- 
five 6-hour endurance test cycles; and 

(ii) Rated takeoff power or thrust 

during ten of the twenty-five 6-hour en-
durance test cycles. 

(3) 

Rated maximum continuous power or 

thrust.  One hour and 30 minutes at 
rated maximum continuous power or 
thrust. 

(4) 

Incremental cruise power or thrust. 

Two hours and 30 minutes at the suc-
cessive power lever positions cor-
responding to at least 15 approximately 
equal speed and time increments be-
tween maximum continuous engine ro-
tational speed and ground or minimum 
idle rotational speed. For engines oper-
ating at constant speed, the thrust and 
power may be varied in place of speed. 
If there is significant peak vibration 
anywhere between ground idle and 
maximum continuous conditions, the 
number of increments chosen may be 
changed to increase the amount of run-
ning made while subject to the peak vi-
brations up to not more than 50 percent 
of the total time spent in incremental 
running. 

(5) 

Acceleration and deceleration runs. 

30 minutes of accelerations and decel-
erations, consisting of six cycles from 
idling power or thrust to rated takeoff 
power or thrust and maintained at the 
takeoff power lever position for 30 sec-
onds and at the idling power lever posi-
tion for approximately four and one- 
half minutes. In complying with this 
paragraph, the power-control lever 
must be moved from one extreme posi-

tion to the other in not more than one 
second, except that, if different re-
gimes of control operations are incor-
porated necessitating scheduling of the 
power-control lever motion in going 
from one extreme position to the other, 
a longer period of time is acceptable, 
but not more than two seconds. 

(6) 

Starts. One hundred starts must be 

made, of which 25 starts must be pre-
ceded by at least a two-hour engine 
shutdown. There must be at least 10 
false engine starts, pausing for the ap-
plicant’s specified minimum fuel drain-
age time, before attempting a normal 
start. There must be at least 10 normal 
restarts with not longer than 15 min-
utes since engine shutdown. The re-
maining starts may be made after com-
pleting the 150 hours of endurance test-
ing. 

(c) 

Rotorcraft engines for which a 30- 

minute OEI power rating is desired. For 
each rotorcraft engine for which a 30- 
minute OEI power rating is desired, the 
applicant must conduct the following 
series of tests: 

(1) 

Takeoff and idling. One hour of al-

ternate 5-minute periods at rated take-
off power and at idling power. The de-
veloped powers at takeoff and idling 
conditions and their corresponding 
rotor speed and gas temperature condi-
tions must be as established by the 
power control in accordance with the 
schedule established by the applicant. 
During any one period, the rotor speed 
and power may be controlled manually 
while taking data to check perform-
ance. For engines with augmented 
takeoff power ratings that involve in-
creases in turbine inlet temperature, 
rotor speed, or shaft power, this period 
of running at rated takeoff power must 
be at the augmented power rating. In 
changing the power setting after each 
period, the power control lever must be 
moved in the manner prescribed in 
paragraph (c)(6) of this section. 

(2) 

Rated maximum continuous and 

takeoff power. Thirty minutes at— 

(i) Rated maximum continuous power 

during fifteen of the twenty-five 6-hour 
endurance test cycles; and 

(ii) Rated takeoff power during ten of 

the twenty-five 6-hour endurance test 
cycles. 

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732 

14 CFR Ch. I (1–1–24 Edition) 

§ 33.87 

(3) 

Rated maximum continuous power. 

One hour at rated maximum contin-
uous power. 

(4) 

Rated 30-minute OEI power. Thirty 

minutes at rated 30-minute OEI power. 

(5) 

Incremental cruise power. Two 

hours and 30 minutes at the successive 
power lever positions corresponding 
with not less than 15 approximately 
equal speed and time increments be-
tween maximum continuous engine ro-
tational speed and ground or minimum 
idle rotational speed. For engines oper-
ating at constant speed, power may be 
varied in place of speed. If there are 
significant peak vibrations anywhere 
between ground idle and maximum 
continuous conditions, the number of 
increments chosen must be changed to 
increase the amount of running con-
ducted while subject to peak vibrations 
up to not more than 50 percent of the 
total time spent in incremental run-
ning. 

(6) 

Acceleration and deceleration runs. 

Thirty minutes of accelerations and de-
celerations, consisting of six cycles 
from idling power to rated takeoff 
power and maintained at the takeoff 
power lever position for 30 seconds and 
at the idling power lever position for 
approximately 4

1

2

minutes. In com-

plying with this paragraph, the power 
control lever must be moved from one 
extreme position to the other in not 
more than one second. If, however, dif-
ferent regimes of control operations 
are incorporated that necessitate 
scheduling of the power control lever 
motion from one extreme position to 
the other, then a longer period of time 
is acceptable, but not more than two 
seconds. 

(7) 

Starts.  One hundred starts, of 

which 25 starts must be preceded by at 
least a two-hour engine shutdown. 
There must be at least 10 false engine 
starts, pausing for the applicant’s spec-
ified minimum fuel drainage time, be-
fore attempting a normal start. There 
must be at least 10 normal restarts not 
more than 15 minutes after engine 
shutdown. The remaining starts may 
be made after completing the 150 hours 
of endurance testing. 

(d) 

Rotorcraft engines for which a con-

tinuous OEI rating is desired. For each 
rotorcraft engine for which a contin-
uous OEI power rating is desired, the 

applicant must conduct the following 
series of tests: 

(1) 

Takeoff and idling. One hour of al-

ternate 5-minute periods at rated take-
off power and at idling power. The de-
veloped powers at takeoff and idling 
conditions and their corresponding 
rotor speed and gas temperature condi-
tions must be as established by the 
power control in accordance with the 
schedule established by the applicant. 
During any one period the rotor speed 
and power may be controlled manually 
while taking data to check perform-
ance. For engines with augmented 
takeoff power ratings that involve in-
creases in turbine inlet temperature, 
rotor speed, or shaft power, this period 
of running at rated takeoff power must 
be at the augmented power rating. In 
changing the power setting after each 
period, the power control lever must be 
moved in the manner prescribed in 
paragraph (d)(6) of this section. 

(2) 

Rated maximum continuous and 

takeoff power. Thirty minutes at— 

(i) Rated maximum continuous power 

during fifteen of the twenty-five 6-hour 
endurance test cycles; and 

(ii) Rated takeoff power during ten of 

the twenty-five 6-hour endurance test 
cycles. 

(3) 

Rated continuous OEI power. One 

hour at rated continuous OEI power. 

(4) 

Rated maximum continuous power. 

One hour at rated maximum contin-
uous power. 

(5) 

Incremental cruise power. Two 

hours at the successive power lever po-
sitions corresponding with not less 
than 12 approximately equal speed and 
time increments between maximum 
continuous engine rotational speed and 
ground or minimum idle rotational 
speed. For engines operating at con-
stant speed, power may be varied in 
place of speed. If there are significant 
peak vibrations anywhere between 
ground idle and maximum continuous 
conditions, the number of increments 
chosen must be changed to increase the 
amount of running conducted while 
being subjected to the peak vibrations 
up to not more than 50 percent of the 
total time spent in incremental run-
ning. 

(6) 

Acceleration and deceleration runs. 

Thirty minutes of accelerations and de-
celerations, consisting of six cycles 

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733 

Federal Aviation Administration, DOT 

§ 33.87 

from idling power to rated takeoff 
power and maintained at the takeoff 
power lever position for 30 seconds and 
at the idling power lever position for 
approximately 4

1

2

minutes. In com-

plying with this paragraph, the power 
control lever must be moved from one 
extreme position to the other in not 
more than 1 second, except that if dif-
ferent regimes of control operations 
are incorporated necessitating sched-
uling of the power control lever motion 
in going from one extreme position to 
the other, a longer period of time is ac-
ceptable, but not more than 2 seconds. 

(7) 

Starts.  One hundred starts, of 

which 25 starts must be preceded by at 
least a 2-hour engine shutdown. There 
must be at least 10 false engine starts, 
pausing for the applicant’s specified 
minimum fuel drainage time, before at-
tempting a normal start. There must 
be at least 10 normal restarts with not 
longer than 15 minutes since engine 
shutdown. The remaining starts may 
be made after completing the 150 hours 
of endurance testing. 

(e) 

Rotorcraft engines for which a 2

1

2

minute OEI power rating is desired. For 
each rotorcraft engine for which a 2

1

2

minute OEI power rating is desired, the 
applicant must conduct the following 
series of tests: 

(1) 

Takeoff, 2

1

2

-minute OEI, and idling. 

One hour of alternate 5-minute periods 
at rated takeoff power and at idling 
power except that, during the third and 
sixth takeoff power periods, only 2

1

2

 

minutes need be conducted at rated 
takeoff power, and the remaining 2

1

2

 

minutes must be conducted at rated 
2

1

2

-minute OEI power. The developed 

powers at takeoff, 2

1

2

-minute OEI, and 

idling conditions and their cor-
responding rotor speed and gas tem-
perature conditions must be as estab-
lished by the power control in accord-
ance with the schedule established by 
the applicant. The applicant may, dur-
ing any one period, control manually 
the rotor speed and power while taking 
data to check performance. For engines 
with augmented takeoff power ratings 
that involve increases in turbine inlet 
temperature, rotor speed, or shaft 
power, this period of running at rated 
takeoff power must be at the aug-
mented rating. In changing the power 
setting after or during each period, the 

power control lever must be moved in 
the manner prescribed in paragraph 
(b)(5), (c)(6), or (d)(6) of this section, as 
applicable. 

(2) The tests required in paragraphs 

(b)(2) through (b)(6), or (c)(2) through 
(c)(7), or (d)(2) through (d)(7) of this 
section, as applicable, except that in 
one of the 6-hour test sequences, the 
last 5 minutes of the 30 minutes at 
takeoff power test period of paragraph 
(b)(2) of this section, or of the 30 min-
utes at 30-minute OEI power test pe-
riod of paragraph (c)(4) of this section, 
or of the l hour at continuous OEI 
power test period of paragraph (d)(3) of 
this section, must be run at 2

1

2

-minute 

OEI power. 

(f) 

Rotorcraft Engines for which 30-sec-

ond OEI and 2-minute OEI ratings are de-
sired.  
For each rotorcraft engine for 
which 30-second OEI and 2-minute OEI 
power ratings are desired, and fol-
lowing completion of the tests under 
paragraphs (b), (c), (d), or (e) of this 
section, the applicant may disassemble 
the tested engine to the extent nec-
essary to show compliance with the re-
quirements of § 33.93(a). The tested en-
gine must then be reassembled using 
the same parts used during the test 
runs of paragraphs (b), (c), (d), or (e) of 
this section, except those parts de-
scribed as consumables in the Instruc-
tions for Continued Airworthiness. Ad-
ditionally, the tests required in para-
graphs (f)(1) through (f)(8) of this sec-
tion must be run continuously. If a 
stop occurs during these tests, the in-
terrupted sequence must be repeated 
unless the applicant shows that the se-
verity of the test would not be reduced 
if it were continued. The applicant 
must conduct the following test se-
quence four times, for a total time of 
not less than 120 minutes: 

(1) 

Takeoff power. Three minutes at 

rated takeoff power. 

(2) 

30-second OEI power. Thirty sec-

onds at rated 30-second OEI power. 

(3) 

2-minute OEI power. Two minutes 

at rated 2-minute OEI power. 

(4) 

30-minute OEI power, continuous 

OEI power, or maximum continuous 
power.  
Five minutes at whichever is 
the greatest of rated 30-minute OEI 
power, rated continuous OEI power, or 

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734 

14 CFR Ch. I (1–1–24 Edition) 

§ 33.87 

rated maximum continuous power, ex-
cept that, during the first test se-
quence, this period shall be 65 minutes. 
However, where the greatest rated 
power is 30-minute OEI power, that 
sixty-five minute period shall consist 
of 30 minutes at 30-minute OEI power 
followed by 35 minutes at whichever is 
the greater of continuous OEI power or 
maximum continuous power. 

(5) 

50 percent takeoff power. One 

minute at 50 percent takeoff power. 

(6) 

30-second OEI power. Thirty sec-

onds at rated 30-second OEI power. 

(7) 

2-minute OEI power. Two minutes 

at rated 2-minute OEI power. 

(8) 

Idle. One minute at flight idle. 

(g) 

Supersonic aircraft engines. For 

each engine type certificated for use on 
supersonic aircraft the applicant must 
conduct the following: 

(1) 

Subsonic test under sea level ambient 

atmospheric conditions. Thirty runs of 
one hour each must be made, con-
sisting of— 

(i) Two periods of 5 minutes at rated 

takeoff augmented thrust each fol-
lowed by 5 minutes at idle thrust; 

(ii) One period of 5 minutes at rated 

takeoff thrust followed by 5 minutes at 
not more than 15 percent of rated take-
off thrust; 

(iii) One period of 10 minutes at rated 

takeoff augmented thrust followed by 2 
minutes at idle thrust, except that if 
rated maximum continuous augmented 
thrust is lower than rated takeoff aug-
mented thrust, 5 of the 10-minute peri-
ods must be at rated maximum contin-
uous augmented thrust; and 

(iv) Six periods of 1 minute at rated 

takeoff augmented thrust each fol-
lowed by 2 minutes, including accelera-
tion and deceleration time, at idle 
thrust. 

(2) 

Simulated supersonic test. Each run 

of the simulated supersonic test must 
be preceded by changing the inlet air 
temperature and pressure from that at-
tained at subsonic condition to the 
temperature and pressure attained at 
supersonic velocity, and must be fol-
lowed by a return to the temperature 
attained at subsonic condition. Thirty 
runs of 4 hours each must be made, 
consisting of— 

(i) One period of 30 minutes at the 

thrust obtained with the power control 
lever set at the position for rated max-

imum continuous augmented thrust 
followed by 10 minutes at the thrust 
obtained with the power control lever 
set at the position for 90 percent of 
rated maximum continuous augmented 
thrust. The end of this period in the 
first five runs must be made with the 
induction air temperature at the lim-
iting condition of transient over-
temperature, but need not be repeated 
during the periods specified in para-
graphs (g)(2)(ii) through (iv) of this sec-
tion; 

(ii) One period repeating the run 

specified in paragraph (g)(2)(i) of this 
section, except that it must be followed 
by 10 minutes at the thrust obtained 
with the power control lever set at the 
position for 80 percent of rated max-
imum continuous augmented thrust; 

(iii) One period repeating the run 

specified in paragraph (g)(2)(i) of this 
section, except that it must be followed 
by 10 minutes at the thrust obtained 
with the power control lever set at the 
position for 60 percent of rated max-
imum continuous augmented thrust 
and then 10 minutes at not more than 
15 percent of rated takeoff thrust; 

(iv) One period repeating the runs 

specified in paragraphs (g)(2)(i) and (ii) 
of this section; and 

(v) One period of 30 minutes with 25 

of the runs made at the thrust obtained 
with the power control lever set at the 
position for rated maximum contin-
uous augmented thrust, each followed 
by idle thrust and with the remaining 
5 runs at the thrust obtained with the 
power control lever set at the position 
for rated maximum continuous aug-
mented thrust for 25 minutes each, fol-
lowed by subsonic operation at not 
more than 15 percent or rated takeoff 
thrust and accelerated to rated takeoff 
thrust for 5 minutes using hot fuel. 

(3) 

Starts. One hundred starts must be 

made, of which 25 starts must be pre-
ceded by an engine shutdown of at 
least 2 hours. There must be at least 10 
false engine starts, pausing for the ap-
plicant’s specified minimum fuel drain-
age time before attempting a normal 
start. At least 10 starts must be normal 
restarts, each made no later than 15 
minutes after engine shutdown. The 

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735 

Federal Aviation Administration, DOT 

§ 33.91 

starts may be made at any time, in-
cluding the period of endurance test-
ing. 

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as 
amended by Amdt. 33–3, 32 FR 3737, Mar. 4, 
1967; Amdt. 33–6, 39 FR 35468, Oct. 1, 1974; 
Amdt. 33–10, 49 FR 6853, Feb. 23, 1984; Amdt. 
33–12, 53 FR 34220, Sept. 2, 1988; Amdt. 33–18, 
61 FR 31328, June 19, 1996; Amdt. 33–25, 73 FR 
48123, Aug. 18, 2008; Amdt. 33–30, 74 FR 45311, 
Sept. 2, 2009; Amdt. 33–32, 77 FR 22187, Apr. 
13, 2012] 

§ 33.88

Engine overtemperature test. 

(a) Each engine must run for 5 min-

utes at maximum permissible rpm with 
the gas temperature at least 75 

°

F (42 

°

C) higher than the maximum rating’s 

steady-state operating limit, excluding 
maximum values of rpm and gas tem-
perature associated with the 30-second 
OEI and 2-minute OEI ratings. Fol-
lowing this run, the turbine assembly 
must be within serviceable limits. 

(b) In addition to the test require-

ments in paragraph (a) of this section, 
each engine for which 30-second OEI 
and 2-minute OEI ratings are desired, 
that incorporates a means for auto-
matic temperature control within its 
operating limitations in accordance 
with § 33.28(k), must run for a period of 
4 minutes at the maximum power-on 
rpm with the gas temperature at least 
35 

°

F (19 

°

C) higher than the maximum 

operating limit at 30-second OEI rat-
ing. Following this run, the turbine as-
sembly may exhibit distress beyond the 
limits for an overtemperature condi-
tion provided the engine is shown by 
analysis or test, as found necessary by 
the FAA, to maintain the integrity of 
the turbine assembly. 

(c) A separate test vehicle may be 

used for each test condition. 

[Doc. No. 26019, 61 FR 31329, June 19, 1996, as 
amended by Amdt. 33–25, 73 FR 48124, Aug. 18, 
2008; Amdt. 33–26, 73 FR 48285, Aug. 19, 2008] 

§ 33.89

Operation test. 

(a) The operation test must include 

testing found necessary by the Admin-
istrator to demonstrate— 

(1) Starting, idling, acceleration, 

overspeeding, ignition, functioning of 
the propeller (if the engine is des-
ignated to operate with a propeller); 

(2) Compliance with the engine re-

sponse requirements of § 33.73; and 

(3) The minimum power or thrust re-

sponse time to 95 percent rated takeoff 
power or thrust, from power lever posi-
tions representative of minimum idle 
and of minimum flight idle, starting 
from stabilized idle operation, under 
the following engine load conditions: 

(i) No bleed air and power extraction 

for aircraft use. 

(ii) Maximum allowable bleed air and 

power extraction for aircraft use. 

(iii) An intermediate value for bleed 

air and power extraction representa-
tive of that which might be used as a 
maximum for aircraft during approach 
to a landing. 

(4) If testing facilities are not avail-

able, the determination of power ex-
traction required in paragraph (a)(3)(ii) 
and (iii) of this section may be accom-
plished through appropriate analytical 
means. 

(b) The operation test must include 

all testing found necessary by the Ad-
ministrator to demonstrate that the 
engine has safe operating characteris-
tics throughout its specified operating 
envelope. 

[Amdt. 33–4, 36 FR 5493, Mar. 24, 1971, as 
amended by Amdt. 33–6, 39 FR 35469, Oct. 1, 
1974; Amdt. 33–10, 49 FR 6853, Feb. 23, 1984] 

§ 33.90

Initial maintenance inspection 

test. 

Each applicant, except an applicant 

for an engine being type certificated 
through amendment of an existing type 
certificate or through supplemental 
type certification procedures, must 
complete one of the following tests on 
an engine that substantially conforms 
to the type design to establish when 
the initial maintenance inspection is 
required: 

(a) An approved engine test that sim-

ulates the conditions in which the en-
gine is expected to operate in service, 
including typical start-stop cycles. 

(b) An approved engine test con-

ducted in accordance with § 33.201 (c) 
through (f). 

[Doc. No. FAA–2002–6717, 72 FR 1877, Jan. 16, 
2007] 

§ 33.91

Engine system and component 

tests. 

(a) For those systems or components 

that cannot be adequately substan-
tiated in accordance with endurance 

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