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14 CFR Ch. I (1–1–18 Edition) 

§ 29.903 

(1) Is necessary for propulsion; 
(2) Affects the control of the major 

propulsive units; or 

(3) Affects the safety of the major 

propulsive units between normal in-
spections or overhauls. 

(b) For each powerplant installa-


(1) The installation must comply 


(i) The installation instructions pro-

vided under § 33.5 of this chapter; and 

(ii) The applicable provisions of this 


(2) Each component of the installa-

tion must be constructed, arranged, 
and installed to ensure its continued 
safe operation between normal inspec-
tions or overhauls for the range of tem-
perature and altitude for which ap-
proval is requested. 

(3) Accessibility must be provided to 

allow any inspection and maintenance 
necessary for continued airworthiness; 

(4) Electrical interconnections must 

be provided to prevent differences of 
potential between major components of 
the installation and the rest of the 

(5) Axial and radial expansion of tur-

bine engines may not affect the safety 
of the installation. 

(6) Design precautions must be taken 

to minimize the possibility of incorrect 
assembly of components and equipment 
essential to safe operation of the rotor-
craft, except where operation with the 
incorrect assembly can be shown to be 
extremely improbable. 

(c) For each powerplant and auxiliary 

power unit installation, it must be es-
tablished that no single failure or mal-
function or probable combination of 
failures will jeopardize the safe oper-
ation of the rotorcraft except that the 
failure of structural elements need not 
be considered if the probability of any 
such failure is extremely remote. 

(d) Each auxiliary power unit instal-

lation must meet the applicable provi-
sions of this subpart. 

(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. 29–3, 33 FR 969, Jan. 26, 
1968; Amdt. 29–13, 42 FR 15046, Mar. 17, 1977; 
Amdt. 29–17, 43 FR 50600, Oct. 30, 1978; Amdt. 
29–26, 53 FR 34215, Sept. 2, 1988; Amdt. 29–36, 
60 FR 55776, Nov. 2, 1995] 

§ 29.903


(a)  Engine type certification. Each en-

gine must have an approved type cer-
tificate. Reciprocating engines for use 
in helicopters must be qualified in ac-
cordance with § 33.49(d) of this chapter 
or be otherwise approved for the in-
tended usage. 

(b)  Category A; engine isolation. For 

each category A rotorcraft, the power-
plants must be arranged and isolated 
from each other to allow operation, in 
at least one configuration, so that the 
failure or malfunction of any engine, or 
the failure of any system that can af-
fect any engine, will not— 

(1) Prevent the continued safe oper-

ation of the remaining engines; or 

(2) Require immediate action, other 

than normal pilot action with primary 
flight controls, by any crewmember to 
maintain safe operation. 

(c)  Category A; control of engine rota-

tion.  For each Category A rotorcraft, 
there must be a means for stopping the 
rotation of any engine individually in 
flight, except that, for turbine engine 
installations, the means for stopping 
the engine need be provided only where 
necessary for safety. In addition— 

(1) Each component of the engine 

stopping system that is located on the 
engine side of the firewall, and that 
might be exposed to fire, must be at 
least fire resistant; or 

(2) Duplicate means must be avail-

able for stopping the engine and the 
controls must be where all are not like-
ly to be damaged at the same time in 
case of fire. 

(d)  Turbine engine installation. For 

turbine engine installations— 

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