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14 CFR Ch. I (1–1–14 Edition)
§ 25.934
§ 25.934
Turbojet engine thrust re-
verser system tests.
Thrust reversers installed on tur-
bojet engines must meet the require-
ments of § 33.97 of this chapter.
[Amdt. 25–23, 35 FR 5677, Apr. 8, 1970]
§ 25.937
Turbopropeller-drag limiting
systems.
Turbopropeller power airplane pro-
peller-drag limiting systems must be
designed so that no single failure or
malfunction of any of the systems dur-
ing normal or emergency operation re-
sults in propeller drag in excess of that
for which the airplane was designed
under § 25.367. Failure of structural ele-
ments of the drag limiting systems
need not be considered if the prob-
ability of this kind of failure is ex-
tremely remote.
§ 25.939
Turbine engine operating
characteristics.
(a) Turbine engine operating charac-
teristics must be investigated in flight
to determine that no adverse charac-
teristics (such as stall, surge, or flame-
out) are present, to a hazardous degree,
during normal and emergency oper-
ation within the range of operating
limitations of the airplane and of the
engine.
(b) [Reserved]
(c) The turbine engine air inlet sys-
tem may not, as a result of air flow dis-
tortion during normal operation, cause
vibration harmful to the engine.
[Amdt. 25–11, 32 FR 6912, May 5, 1967, as
amended by Amdt. 25–40, 42 FR 15043, Mar. 17,
1977]
§ 25.941
Inlet, engine, and exhaust
compatibility.
For airplanes using variable inlet or
exhaust system geometry, or both—
(a) The system comprised of the
inlet, engine (including thrust aug-
mentation systems, if incorporated),
and exhaust must be shown to function
properly under all operating conditions
for which approval is sought, including
all engine rotating speeds and power
settings, and engine inlet and exhaust
configurations;
(b) The dynamic effects of the oper-
ation of these (including consideration
of probable malfunctions) upon the aer-
odynamic control of the airplane may
not result in any condition that would
require exceptional skill, alertness, or
strength on the part of the pilot to
avoid exceeding an operational or
structural limitation of the airplane;
and
(c) In showing compliance with para-
graph (b) of this section, the pilot
strength required may not exceed the
limits set forth in § 25.143(d), subject to
the conditions set forth in paragraphs
(e) and (f) of § 25.143.
[Amdt. 25–38, 41 FR 55467, Dec. 20, 1976, as
amended by Amdt. 25–121, 72 FR 44669, Aug. 8,
2007]
§ 25.943
Negative acceleration.
No hazardous malfunction of an en-
gine, an auxiliary power unit approved
for use in flight, or any component or
system associated with the powerplant
or auxiliary power unit may occur
when the airplane is operated at the
negative accelerations within the
flight envelopes prescribed in § 25.333.
This must be shown for the greatest
duration expected for the acceleration.
[Amdt. 25–40, 42 FR 15043, Mar. 17, 1977]
§ 25.945
Thrust or power augmentation
system.
(a)
General. Each fluid injection sys-
tem must provide a flow of fluid at the
rate and pressure established for proper
engine functioning under each intended
operating condition. If the fluid can
freeze, fluid freezing may not damage
the airplane or adversely affect air-
plane performance.
(b)
Fluid tanks. Each augmentation
system fluid tank must meet the fol-
lowing requirements:
(1) Each tank must be able to with-
stand without failure the vibration, in-
ertia, fluid, and structural loads that it
may be subject to in operation.
(2) The tanks as mounted in the air-
plane must be able to withstand with-
out failure or leakage an internal pres-
sure 1.5 times the maximum operating
pressure.
(3) If a vent is provided, the venting
must be effective under all normal
flight conditions.
(4) [Reserved]
(5) Each tank must have an expan-
sion space of not less than 2 percent of
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