763 

Federal Aviation Administration, DOT 

§ 35.41 

fixed-pitch wood propellers of conven-
tional design. 

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008] 

§ 35.39

Endurance test. 

Endurance tests on the propeller sys-

tem must be made on a representative 
engine in accordance with paragraph 
(a) or (b) of this section, as applicable, 
without evidence of failure or malfunc-
tion. 

(a) Fixed-pitch and ground adjust-

able-pitch propellers must be subjected 
to one of the following tests: 

(1) A 50-hour flight test in level flight 

or in climb. The propeller must be op-
erated at takeoff power and rated rota-
tional speed during at least five hours 
of this flight test, and at not less than 
90 percent of the rated rotational speed 
for the remainder of the 50 hours. 

(2) A 50-hour ground test at takeoff 

power and rated rotational speed. 

(b) Variable-pitch propellers must be 

subjected to one of the following tests: 

(1) A 110-hour endurance test that 

must include the following conditions: 

(i) Five hours at takeoff power and 

rotational speed and thirty 10-minute 
cycles composed of: 

(A) Acceleration from idle, 
(B) Five minutes at takeoff power 

and rotational speed, 

(C) Deceleration, and 
(D) Five minutes at idle. 
(ii) Fifty hours at maximum contin-

uous power and rotational speed, 

(iii) Fifty hours, consisting of ten 5- 

hour cycles composed of: 

(A) Five accelerations and decelera-

tions between idle and takeoff power 
and rotational speed, 

(B) Four and one half hours at ap-

proximately even incremental condi-
tions from idle up to, but not includ-
ing, maximum continuous power and 
rotational speed, and 

(C) Thirty minutes at idle. 
(2) The operation of the propeller 

throughout the engine endurance tests 
prescribed in part 33 of this chapter. 

(c) An analysis based on tests of pro-

pellers of similar design may be used in 
place of the tests of paragraphs (a) and 
(b) of this section. 

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008] 

§ 35.40

Functional test. 

The variable-pitch propeller system 

must be subjected to the applicable 
functional tests of this section. The 
same propeller system used in the en-
durance test (§ 35.39) must be used in 
the functional tests and must be driven 
by a representative engine on a test 
stand or on an airplane. The propeller 
must complete these tests without evi-
dence of failure or malfunction. This 
test may be combined with the endur-
ance test for accumulation of cycles. 

(a) Manually-controllable propellers. 

Five hundred representative flight cy-
cles must be made across the range of 
pitch and rotational speed. 

(b) Governing propellers. Fifteen 

hundred complete cycles must be made 
across the range of pitch and rota-
tional speed. 

(c) Feathering propellers. Fifty cy-

cles of feather and unfeather operation 
must be made. 

(d) Reversible-pitch propellers. Two 

hundred complete cycles of control 
must be made from lowest normal 
pitch to maximum reverse pitch. Dur-
ing each cycle, the propeller must run 
for 30 seconds at the maximum power 
and rotational speed selected by the 
applicant for maximum reverse pitch. 

(e) An analysis based on tests of pro-

pellers of similar design may be used in 
place of the tests of this section. 

[Amdt. 35–8, 73 FR 63349, Oct. 24, 2008] 

§ 35.41

Overspeed and overtorque. 

(a) When the applicant seeks ap-

proval of a transient maximum pro-
peller overspeed, the applicant must 
demonstrate that the propeller is capa-
ble of further operation without main-
tenance action at the maximum pro-
peller overspeed condition. This may 
be accomplished by: 

(1) Performance of 20 runs, each of 30 

seconds duration, at the maximum pro-
peller overspeed condition; or 

(2) Analysis based on test or service 

experience. 

(b) When the applicant seeks ap-

proval of a transient maximum pro-
peller overtorque, the applicant must 

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