[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR25.149]
[Page 354-355]
TITLE 14--AERONAUTICS AND SPACE
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES--Table of Contents
Subpart B--Flight
Sec. 25.149 Minimum control speed.
(a) In establishing the minimum control speeds required by this
section, the method used to simulate critical engine failure must
represent the most critical mode of powerplant failure with respect to
controllability expected in service.
(b) VMC is the calibrated airspeed at which, when the
critical engine is suddenly made inoperative, it is possible to maintain
control of the airplane with that engine still inoperative and maintain
straight flight with an angle of bank of not more than 5 degrees.
(c) VMC may not exceed 1.13 VSR with--
(1) Maximum available takeoff power or thrust on the engines;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for takeoff;
(4) The maximum sea level takeoff weight (or any lesser weight
necessary to show VMC);
(5) The airplane in the most critical takeoff configuration existing
along the flight path after the airplane becomes airborne, except with
the landing gear retracted;
(6) The airplane airborne and the ground effect negligible; and
(7) If applicable, the propeller of the inoperative engine--
(i) Windmilling;
(ii) In the most probable position for the specific design of the
propeller control; or
(iii) Feathered, if the airplane has an automatic feathering device
acceptable for showing compliance with the climb requirements of
Sec. 25.121.
(d) The rudder forces required to maintain control at VMC
may not exceed 150 pounds nor may it be necessary to reduce power or
thrust of the operative engines. During recovery, the airplane may not
assume any dangerous attitude or require exceptional piloting skill,
alertness, or strength to prevent a heading change of more than 20
degrees.
(e) VMCG, the minimum control speed on the ground, is the
calibrated airspeed during the takeoff run at which, when the critical
engine is suddenly made inoperative, it is possible to maintain control
of the airplane using the rudder control alone (without the use of
nosewheel steering), as limited by 150 pounds of force, and the lateral
control to the extent of keeping the wings level to enable the takeoff
to be safely continued using normal piloting skill. In the determination
of VMCG, assuming that the path of the airplane accelerating
with all engines operating is along the centerline of the runway, its
path from the point at which the critical engine is made inoperative to
the point at which recovery to a direction parallel to the centerline is
completed may not deviate more than 30 feet laterally from the
centerline at any point. VMCG must be established with--
(1) The airplane in each takeoff configuration or, at the option of
the applicant, in the most critical takeoff configuration;
(2) Maximum available takeoff power or thrust on the operating
engines;
(3) The most unfavorable center of gravity;
(4) The airplane trimmed for takeoff; and
(5) The most unfavorable weight in the range of takeoff weights.
(f) VMCL, the minimum control speed during approach and
landing with all
[[Page 355]]
engines operating, is the calibrated airspeed at which, when the
critical engine is suddenly made inoperative, it is possible to maintain
control of the airplane with that engine still inoperative, and maintain
straight flight with an angle of bank of not more than 5 degrees.
VMCL must be established with--
(1) The airplane in the most critical configuration (or, at the
option of the applicant, each configuration) for approach and landing
with all engines operating;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for approach with all engines operating;
(4) The most favorable weight, or, at the option of the applicant,
as a function of weight;
(5) For propeller airplanes, the propeller of the inoperative engine
in the position it achieves without pilot action, assuming the engine
fails while at the power or thrust necessary to maintain a three degree
approach path angle; and
(6) Go-around power or thrust setting on the operating engine(s).
(g) For airplanes with three or more engines, VMCL-2, the
minimum control speed during approach and landing with one critical
engine inoperative, is the calibrated airspeed at which, when a second
critical engine is suddenly made inoperative, it is possible to maintain
control of the airplane with both engines still inoperative, and
maintain straight flight with an angle of bank of not more than 5
degrees. VMCL-2 must be established with--
(1) The airplane in the most critical configuration (or, at the
option of the applicant, each configuration) for approach and landing
with one critical engine inoperative;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for approach with one critical engine
inoperative;
(4) The most unfavorable weight, or, at the option of the applicant,
as a function of weight;
(5) For propeller airplanes, the propeller of the more critical
inoperative engine in the position it achieves without pilot action,
assuming the engine fails while at the power or thrust necessary to
maintain a three degree approach path angle, and the propeller of the
other inoperative engine feathered;
(6) The power or thrust on the operating engine(s) necessary to
maintain an approach path angle of three degrees when one critical
engine is inoperative; and
(7) The power or thrust on the operating engine(s) rapidly changed,
immediately after the second critical engine is made inoperative, from
the power or thrust prescribed in paragraph (g)(6) of this section to--
(i) Minimum power or thrust; and
(ii) Go-around power or thrust setting.
(h) In demonstrations of VMCL and VMCL-2--
(1) The rudder force may not exceed 150 pounds;
(2) The airplane may not exhibit hazardous flight characteristics or
require exceptional piloting skill, alertness, or strength;
(3) Lateral control must be sufficient to roll the airplane, from an
initial condition of steady flight, through an angle of 20 degrees in
the direction necessary to initiate a turn away from the inoperative
engine(s), in not more than 5 seconds; and
(4) For propeller airplanes, hazardous flight characteristics must
not be exhibited due to any propeller position achieved when the engine
fails or during any likely subsequent movements of the engine or
propeller controls.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-42,
43 FR 2321, Jan. 16, 1978; Amdt. 25-72, 55 FR 29774, July 20, 1990; 55
FR 37607, Sept. 12, 1990; Amdt. 25-84, 60 FR 30749, June 9, 1995; Amdt.
25-108, 67 FR 70827, Nov. 26, 2002]
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