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14 CFR Ch. I (1–1–24 Edition) 

§ 29.1025 

§ 29.1025

Oil valves. 

(a) Each oil shutoff must meet the re-

quirements of § 29.1189. 

(b) The closing of oil shutoffs may 

not prevent autorotation. 

(c) Each oil valve must have positive 

stops or suitable index provisions in 
the ‘‘on’’ and ‘‘off’’ positions and must 
be supported so that no loads resulting 
from its operation or from accelerated 
flight conditions are transmitted to 
the lines attached to the valve. 

§ 29.1027

Transmission and gearboxes: 

general. 

(a) The oil system for components of 

the rotor drive system that require 
continuous lubrication must be suffi-
ciently independent of the lubrication 
systems of the engine(s) to ensure— 

(1) Operation with any engine inoper-

ative; and 

(2) Safe autorotation. 
(b) Pressure lubrication systems for 

transmissions and gearboxes must 
comply with the requirements of 
§§ 29.1013, paragraphs (c), (d), and (f) 
only, 29.1015, 29.1017, 29.1021, 29.1023, and 
29.1337(d). In addition, the system must 
have— 

(1) An oil strainer or filter through 

which all the lubricant flows, and 
must— 

(i) Be designed to remove from the 

lubricant any contaminant which may 
damage transmission and drive system 
components or impede the flow of lu-
bricant to a hazardous degree; and 

(ii) Be equipped with a bypass con-

structed and installed so that— 

(A) The lubricant will flow at the 

normal rate through the rest of the 
system with the strainer or filter com-
pletely blocked; and 

(B) The release of collected contami-

nants is minimized by appropriate lo-
cation of the bypass to ensure that col-
lected contaminants are not in the by-
pass flowpath; 

(iii) Be equipped with a means to in-

dicate collection of contaminants on 
the filter or strainer at or before open-
ing of the bypass; 

(2) For each lubricant tank or sump 

outlet supplying lubrication to rotor 
drive systems and rotor drive system 
components, a screen to prevent en-
trance into the lubrication system of 
any object that might obstruct the 

flow of lubricant from the outlet to the 
filter required by paragraph (b)(1) of 
this section. The requirements of para-
graph (b)(1) of this section do not apply 
to screens installed at lubricant tank 
or sump outlets. 

(c) Splash type lubrication systems 

for rotor drive system gearboxes must 
comply with §§ 29.1021 and 29.1337(d). 

[Amdt. 29–26, 53 FR 34218, Sept. 2, 1988] 

C

OOLING

 

§ 29.1041

General. 

(a) The powerplant and auxiliary 

power unit cooling provisions must be 
able to maintain the temperatures of 
powerplant components, engine fluids, 
and auxiliary power unit components 
and fluids within the temperature lim-
its established for these components 
and fluids, under ground, water, and 
flight operating conditions for which 
certification is requested, and after 
normal engine or auxiliary power unit 
shutdown, or both. 

(b) There must be cooling provisions 

to maintain the fluid temperatures in 
any power transmission within safe 
values under any critical surface 
(ground or water) and flight operating 
conditions. 

(c) Except for ground-use-only auxil-

iary power units, compliance with 
paragraphs (a) and (b) of this section 
must be shown by flight tests in which 
the temperatures of selected power-
plant component and auxiliary power 
unit component, engine, and trans-
mission fluids are obtained under the 
conditions prescribed in those para-
graphs. 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–26, 53 FR 34218, Sept. 2, 
1988] 

§ 29.1043

Cooling tests. 

(a) 

General.  For the tests prescribed 

in § 29.1041(c), the following apply: 

(1) If the tests are conducted under 

conditions deviating from the max-
imum ambient atmospheric tempera-
ture specified in paragraph (b) of this 
section, the recorded powerplant tem-
peratures must be corrected under 
paragraphs (c) and (d) of this section, 
unless a more rational correction 
method is applicable. 

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