469 

Federal Aviation Administration, DOT 

§ 25.903 

(i) The installation instructions pro-

vided under §§ 33.5 and 35.3 of this chap-
ter; and 

(ii) The applicable provisions of this 

subpart; 

(2) The components of the installa-

tion must be constructed, arranged, 
and installed so as to ensure their con-
tinued safe operation between normal 
inspections or overhauls; 

(3) The installation must be acces-

sible for necessary inspections and 
maintenance; and 

(4) The major components of the in-

stallation must be electrically bonded 
to the other parts of the airplane. 

(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 airplane except that the 
failure of structural elements need not 
be considered if the probability of such 
failure is extremely remote. 

(d) Each auxiliary power unit instal-

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

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–23, 35 FR 5676, Apr. 8, 
1970; Amdt. 25–40, 42 FR 15042, Mar. 17, 1977; 
Amdt. 25–46, 43 FR 50597, Oct. 30, 1978; Amdt. 
25–126, 73 FR 63345, Oct. 24, 2008] 

§ 25.903

Engines. 

(a) 

Engine type certificate. (1) Each en-

gine must have a type certificate and 
must meet the applicable requirements 
of part 34 of this chapter. 

(2) Each turbine engine must comply 

with one of the following: 

(i) Sections 33.76, 33.77 and 33.78 of 

this chapter in effect on December 13, 
2000, or as subsequently amended; or 

(ii) Sections 33.77 and 33.78 of this 

chapter in effect on April 30, 1998, or as 
subsequently amended before Decem-
ber 13, 2000; or 

(iii) Comply with § 33.77 of this chap-

ter in effect on October 31, 1974, or as 
subsequently amended prior to April 
30, 1998, unless that engine’s foreign ob-
ject ingestion service history has re-
sulted in an unsafe condition; or 

(iv) Be shown to have a foreign object 

ingestion service history in similar in-
stallation locations which has not re-
sulted in any unsafe condition. 

N

OTE

: § 33.77 of this chapter in effect on Oc-

tober 31, 1974, was published in 14 CFR parts 
1 to 59, Revised as of January 1, 1975. See 39 
FR 35467, October 1, 1974. 

(b) 

Engine isolation. The powerplants 

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 
of any system that can affect the en-
gine, will not— 

(1) Prevent the continued safe oper-

ation of the remaining engines; or 

(2) Require immediate action by any 

crewmember for continued safe oper-
ation. 

(c) 

Control of engine rotation. There 

must be means for stopping the rota-
tion of any engine individually in 
flight, except that, for turbine engine 
installations, the means for stopping 
the rotation of any engine need be pro-
vided only where continued rotation 
could jeopardize the safety of the air-
plane. Each component of the stopping 
system on the engine side of the fire-
wall that might be exposed to fire must 
be at least fire-resistant. If hydraulic 
propeller feathering systems are used 
for this purpose, the feathering lines 
must be at least fire resistant under 
the operating conditions that may be 
expected to exist during feathering. 

(d) 

Turbine engine installations. For 

turbine engine installations— 

(1) Design precautions must be taken 

to minimize the hazards to the airplane 
in the event of an engine rotor failure 
or of a fire originating within the en-
gine which burns through the engine 
case. 

(2) The powerplant systems associ-

ated with engine control devices, sys-
tems, and instrumentation, must be de-
signed to give reasonable assurance 
that those engine operating limitations 
that adversely affect turbine rotor 
structural integrity will not be exceed-
ed in service. 

(e) 

Restart capability. (1) Means to re-

start any engine in flight must be pro-
vided. 

(2) An altitude and airspeed envelope 

must be established for in-flight engine 
restarting, and each engine must have 
a restart capability within that enve-
lope. 

(3) For turbine engine powered air-

planes, if the minimum windmilling 

VerDate Mar<15>2010 

10:12 Mar 18, 2014

Jkt 232046

PO 00000

Frm 00479

Fmt 8010

Sfmt 8010

Y:\SGML\232046.XXX

232046

pmangrum on DSK3VPTVN1PROD with CFR