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709 

Federal Aviation Administration, DOT 

§ 33.49 

occur within the endurance limit stress 
of the material. 

(c) Each accessory drive and mount-

ing attachment must be loaded, with 
the loads imposed by each accessory 
used only for an aircraft service being 
the limit load specified by the appli-
cant for the drive or attachment point. 

(d) The vibration survey described in 

paragraph (a) of this section must be 
repeated with that cylinder not firing 
which has the most adverse vibration 
effect, in order to establish the condi-
tions under which the engine can be op-
erated safely in that abnormal state. 
However, for this vibration survey, the 
engine speed range need only extend 
from idle to the maximum desired 
takeoff speed, and compliance with 
paragraph (b) of this section need not 
be shown. 

[Amdt. 33–6, 39 FR 35465, Oct. 1, 1974, as 
amended by Amdt. 33–10, 49 FR 6851, Feb. 23, 
1984] 

§ 33.45

Calibration tests. 

(a) Each engine must be subjected to 

the calibration tests necessary to es-
tablish its power characteristics and 
the conditions for the endurance test 
specified in § 33.49. The results of the 
power characteristics calibration tests 
form the basis for establishing the 
characteristics of the engine over its 
entire operating range of crankshaft 
rotational speeds, manifold pressures, 
fuel/air mixture settings, and altitudes. 
Power ratings are based upon standard 
atmospheric conditions with only those 
accessories installed which are essen-
tial 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. Any change in power charac-
teristics which occurs during the en-
durance 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. 

[Doc. No. 3025, 29 FR 7453, June 10, 1964, as 
amended by Amdt. 33–6, 39 FR 35465, Oct. 1, 
1974] 

§ 33.47

Detonation test. 

Each engine must be tested to estab-

lish that the engine can function with-

out detonation throughout its range of 
intended conditions of operation. 

§ 33.49

Endurance test. 

(a) 

General. Each engine must be sub-

jected to an endurance test that in-
cludes a total of 150 hours of operation 
(except as provided in paragraph 
(e)(1)(iii) of this section) and, depend-
ing upon the type and contemplated 
use of the engine, consists of one of the 
series of runs specified in paragraphs 
(b) through (e) of this section, as appli-
cable. The runs must be made in the 
order found appropriate by the Admin-
istrator for the particular engine being 
tested. During the endurance test the 
engine power and the crankshaft rota-
tional speed must be kept within 

±

percent of the rated values. During the 
runs at rated takeoff power and for at 
least 35 hours at rated maximum con-
tinuous power, one cylinder must be 
operated at not less than the limiting 
temperature, the other cylinders must 
be operated at a temperature not lower 
than 50 degrees F. below the limiting 
temperature, and the oil inlet tempera-
ture must be maintained within 

±

10 de-

grees F. of the limiting temperature. 
An engine that is equipped with a pro-
peller shaft must be fitted for the en-
durance test with a propeller that 
thrust-loads the engine to the max-
imum thrust which the engine is de-
signed to resist at each applicable op-
erating condition specified in this sec-
tion. Each accessory drive and mount-
ing attachment must be loaded. During 
operation at rated takeoff power and 
rated maximum continuous power, the 
load imposed by each accessory used 
only for an aircraft service must be the 
limit load specified by the applicant 
for the engine drive or attachment 
point. 

(b) 

Unsupercharged engines and en-

gines incorporating a gear-driven single- 
speed supercharger. 
For engines not in-
corporating a supercharger and for en-
gines incorporating a gear-driven sin-
gle-speed supercharger the applicant 
must conduct the following runs: 

(1) A 30-hour run consisting of alter-

nate periods of 5 minutes at rated take-
off power with takeoff speed, and 5 
minutes at maximum best economy 
cruising power or maximum rec-
ommended cruising power. 

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