Federal Aviation Administration, DOT

Section 25.1521

Section 25.1511 Flap extended speed.
The established flap extended speed
VFE must be established so that it does
not exceed the design flap speed VF
chosen under SectionSection 25.335(e) and 25.345, for
the corresponding flap positions and
engine powers.
Section 25.1513 Minimum control speed.
The minimum control speed VMC determined under Section 25.149 must be established as an operating limitation.
Section 25.1515 Landing gear speeds.
(a) The established landing gear operating speed or speeds, VLO, may not exceed the speed at which it is safe both
to extend and to retract the landing
gear, as determined under Section 25.729 or by
flight characteristics. If the extension
speed is not the same as the retraction
speed, the two speeds must be designated as VLO(EXT) and VLO(RET), respectively.
(b) The established landing gear extended speed VLE may not exceed the
speed at which it is safe to fly with the
landing gear secured in the fully extended position, and that determined
under Section 25.729.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-38, 41 FR 55468, Dec. 20,
1976]

Section 25.1516 Other speed limitations.
Any other limitation associated with
speed must be established.

spaschal on DSK3GDR082PROD with CFR

[Doc. No. 2000-8511, 66 FR 34024, June 26, 2001]

Section 25.1517 Rough air speed, VRA.
(a) A rough air speed, VRA, for use as
the recommended turbulence penetration airspeed, and a rough air Mach
number, MRA, for use as the recommended
turbulence
penetration
Mach number, must be established.
VRA/MRA must be sufficiently less than
VMO/MMO to ensure that likely speed
variation during rough air encounters
will not cause the overspeed warning to
operate too frequently.
(b) At altitudes where VMO is not limited by Mach number, in the absence of
a rational investigation substantiating
the use of other values, VRA must be
less than VMO - 35 KTAS.
(c) At altitudes where VMO is limited
by Mach number, MRA may be chosen

to provide an optimum margin between
low and high speed buffet boundaries.
[Amdt. 25-141, 79 FR 73469, Dec. 11, 2014]

Section 25.1519 Weight, center of gravity, and
weight distribution.
The airplane weight, center of gravity, and weight distribution limitations determined under SectionSection 25.23 through
25.27 must be established as operating
limitations.
Section 25.1521 Powerplant limitations.
(a) General. The powerplant limitations prescribed in this section must be
established so that they do not exceed
the corresponding limits for which the
engines or propellers are type certificated and do not exceed the values on
which compliance with any other requirement of this part is based.
(b) Reciprocating engine installations.
Operating limitations relating to the
following must be established for reciprocating engine installations:
(1) Horsepower or torque, r.p.m.,
manifold pressure, and time at critical
pressure altitude and sea level pressure
altitude for - 
(i) Maximum continuous power (relating to unsupercharged operation or
to operation in each supercharger mode
as applicable); and
(ii) Takeoff power (relating to unsupercharged operation or to operation in
each supercharger mode as applicable).
(2) Fuel grade or specification.
(3) Cylinder head and oil temperatures.
(4) Any other parameter for which a
limitation has been established as part
of the engine type certificate except
that a limitation need not be established for a parameter that cannot be
exceeded during normal operation due
to the design of the installation or to
another established limitation.
(c) Turbine engine installations. Operating limitations relating to the following must be established for turbine
engine installations:
(1) Horsepower, torque or thrust,
r.p.m., gas temperature, and time for - 
(i) Maximum continuous power or
thrust (relating to augmented or unaugmented operation as applicable).
(ii) Takeoff power or thrust (relating
to augmented or unaugmented operation as applicable).

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