711 

Federal Aviation Administration, DOT 

§ 33.49 

(9) A 20-hour run consisting of alter-

nate periods in the lower gear ratio of 
2 hours at rated maximum continuous 
power with maximum continuous 
speed, and 2 hours at maximum best 
economy cruising power and speed or 
at maximum recommended cruising 
power. 

(10) A 5-hour run in the lower gear 

ratio at maximum best economy cruis-
ing power and speed or at maximum 
recommended cruising power and 
speed. 

Where simulated altitude test equip-
ment is not available when operating 
in the higher gear ratio, the runs may 
be made at the observed horsepower ob-
tained with the critical altitude mani-
fold pressure or specified percentages 
thereof, and the fuel-air mixtures may 
be adjusted to be rich enough to sup-
press detonation. 

(d) 

Helicopter engines. 

To be eligible 

for use on a helicopter each engine 
must either comply with paragraphs 
(a) through (j) of § 29.923 of this chap-
ter, or must undergo the following se-
ries of runs: 

(1) A 35-hour run consisting of alter-

nate periods of 30 minutes each at 
rated takeoff power with takeoff speed, 
and at rated maximum continuous 
power with maximum continuous 
speed. 

(2) A 25-hour run consisting of alter-

nate periods of 2

1

⁄

2

hours each at rated 

maximum continuous power with max-
imum continuous speed, and at 70 per-
cent rated maximum continuous power 
with maximum continuous speed. 

(3) A 25-hour run consisting of alter-

nate periods of 2

1

⁄

2

hours each at rated 

maximum continuous power with max-
imum continuous speed, and at 70 per-
cent rated maximum continuous power 
with 80 to 90 percent maximum contin-
uous speed. 

(4) A 25-hour run consisting of alter-

nate periods of 2

1

⁄

2

hours each at 30 per-

cent rated maximum continuous power 
with takeoff speed, and at 30 percent 
rated maximum continuous power with 
80 to 90 percent maximum continuous 
speed. 

(5) A 25-hour run consisting of alter-

nate periods of 2

1

⁄

2

hours each at 80 per-

cent rated maximum continuous power 
with takeoff speed, and at either rated 
maximum continuous power with 110 

percent maximum continuous speed or 
at rated takeoff power with 103 percent 
takeoff speed, whichever results in the 
greater speed. 

(6) A 15-hour run at 105 percent rated 

maximum continuous power with 105 
percent maximum continuous speed or 
at full throttle and corresponding 
speed at standard sea level carburetor 
entrance pressure, if 105 percent of the 
rated maximum continuous power is 
not exceeded. 

(e) 

Turbosupercharged engines. 

For en-

gines incorporating a turbo-
supercharger the following apply ex-
cept that altitude testing may be simu-
lated provided the applicant shows that 
the engine and supercharger are being 
subjected to mechanical loads and op-
erating temperatures no less severe 
than if run at actual altitude condi-
tions: 

(1) For engines used in airplanes the 

applicant must conduct the runs speci-
fied in paragraph (b) of this section, ex-
cept— 

(i) The entire run specified in para-

graph (b)(1) of this section must be 
made at sea level altitude pressure; 

(ii) The portions of the runs specified 

in paragraphs (b)(2) through (7) of this 
section at rated maximum continuous 
power must be made at critical alti-
tude pressure, and the portions of the 
runs at other power must be made at 
8,000 feet altitude pressure; and 

(iii) The turbosupercharger used dur-

ing the 150-hour endurance test must 
be run on the bench for an additional 50 
hours at the limiting turbine wheel 
inlet gas temperature and rotational 
speed for rated maximum continuous 
power operation unless the limiting 
temperature and speed are maintained 
during 50 hours of the rated maximum 
continuous power operation. 

(2) For engines used in helicopters 

the applicant must conduct the runs 
specified in paragraph (d) of this sec-
tion, except— 

(i) The entire run specified in para-

graph (d)(1) of this section must be 
made at critical altitude pressure; 

(ii) The portions of the runs specified 

in paragraphs (d)(2) and (3) of this sec-
tion at rated maximum continuous 
power must be made at critical alti-
tude pressure and the portions of the 

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