629 

Federal Aviation Administration, DOT 

§ 29.927 

minute OEI torque and the maximum 
speed for use with 30-minute OEI 
torque must be conducted as follows: 
For each engine, in sequence, that en-
gine must be inoperative and the re-
maining engines must be run for a 30- 
minute period. 

(2) 

Continuous OEI power run. 

For 

rotorcraft for which the use of contin-
uous OEI power is requested, a run at 
continuous OEI torque and the max-
imum speed for use with continuous 
OEI torque must be conducted as fol-
lows: For each engine, in sequence, 
that engine must be inoperative and 
the remaining engines must be run for 
1 hour. 

(3) The number of periods prescribed 

in paragraph (k)(1) or (k)(2) of this sec-
tion may not be less than the number 
of engines, nor may it be less than two. 

(l) [Reserved] 
(m) Any components that are af-

fected by maneuvering and gust loads 
must be investigated for the same 
flight conditions as are the main ro-
tors, and their service lives must be de-
termined by fatigue tests or by other 
acceptable methods. In addition, a 
level of safety equal to that of the 
main rotors must be provided for— 

(1) Each component in the rotor drive 

system whose failure would cause an 
uncontrolled landing; 

(2) Each component essential to the 

phasing of rotors on multirotor rotor-
craft, or that furnishes a driving link 
for the essential control of rotors in 
autorotation; and 

(3) Each component common to two 

or more engines on multiengine rotor-
craft. 

(n) 

Special tests. 

Each rotor drive sys-

tem designed to operate at two or more 
gear ratios must be subjected to special 
testing for durations necessary to sub-
stantiate the safety of the rotor drive 
system. 

(o) Each part tested as prescribed in 

this section must be in a serviceable 
condition at the end of the tests. No in-
tervening disassembly which might af-
fect test results may be conducted. 

(p) 

Endurance tests; operating lubri-

cants. 

To be approved for use in rotor 

drive and control systems, lubricants 
must meet the specifications of lubri-
cants used during the tests prescribed 
by this section. Additional or alternate 

lubricants may be qualified by equiva-
lent testing or by comparative analysis 
of lubricant specifications and rotor 
drive and control system characteris-
tics. In addition— 

(1) At least three 10-hour cycles re-

quired by this section must be con-
ducted with transmission and gearbox 
lubricant temperatures, at the location 
prescribed for measurement, not lower 
than the maximum operating tempera-
ture for which approval is requested; 

(2) For pressure lubricated systems, 

at least three 10-hour cycles required 
by this section must be conducted with 
the lubricant pressure, at the location 
prescribed for measurement, not higher 
than the minimum operating pressure 
for which approval is requested; and 

(3) The test conditions of paragraphs 

(p)(1) and (p)(2) of this section must be 
applied simultaneously and must be ex-
tended to include operation at any one- 
engine-inoperative rating for which ap-
proval is requested. 

(Secs. 313(a), 601, 603, 604, Federal Aviation 
Act of 1958 (49 U.S.C. 1354(a), 1421, 1423, 1424), 
sec. 6(c), Dept. of Transportation Act (49 
U.S.C. 1655(c))) 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–1, 30 FR 8778, July 13, 
1965; Amdt. 29–17, 43 FR 50600, Oct. 30, 1978; 
Amdt. 29–26, 53 FR 34215, Sept. 2, 1988; Amdt. 
29–31, 55 FR 38967, Sept. 21, 1990; Amdt. 29–34, 
59 FR 47768, Sept. 16, 1994; Amdt. 29–40, 61 FR 
21908, May 10, 1996; Amdt. 29–42, 63 FR 43285, 
Aug. 12, 1998] 

§ 29.927

Additional tests. 

(a) Any additional dynamic, endur-

ance, and operational tests, and vibra-
tory investigations necessary to deter-
mine that the rotor drive mechanism is 
safe, must be performed. 

(b) If turbine engine torque output to 

the transmission can exceed the high-
est engine or transmission torque 
limit, and that output is not directly 
controlled by the pilot under normal 
operating conditions (such as where 
the primary engine power control is ac-
complished through the flight control), 
the following test must be made: 

(1) Under conditions associated with 

all engines operating, make 200 appli-
cations, for 10 seconds each, of torque 
that is at least equal to the lesser of— 

(i) The maximum torque used in 

meeting § 29.923 plus 10 percent; or 

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