[Federal Register Volume 83, Number 93 (Monday, May 14, 2018)]
[Proposed Rules]
[Pages 22214-22219]
[FR Doc No: 2018-10168]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

Docket No. FAA-2015-0310; Notice No. 25-18-02-SC]

Special Conditions: Gulfstream Aerospace Corporation Model GVII-
G500 Series Airplanes; Flight Envelope Protection--High Incidence
Protection System.

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Gulfstream
Aerospace Corporation (Gulfstream) Model GVII-G500 series airplanes.
These airplanes will have a novel or unusual design feature when
compared to the state of technology and design envisioned in the
airworthiness standards for transport category airplanes. This design
feature is a high incidence protection system that limits the angle of
attack at which the airplane can be flown during normal low speed
operation. The applicable airworthiness regulations do not contain
adequate or appropriate safety standards for this design feature. These
special conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.

DATES: Send your comments on or before June 4, 2018.

ADDRESSES: Send comments identified by docket number FAA-2015-0310
using any of the following methods:
     Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending
your comments electronically.
     Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at<PHONE_NUMBER>.
    Privacy: The FAA will post all comments it receives, without
change, to http://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket website, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478).
    Docket: Background documents or comments received may be read at
http://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, Airframe & Flight Crew
Interface Section, AIR-671, Transport Standards Branch, Policy and
Innovation Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 SE 216th Street, Des Moines, Washington 98098;
telephone and facsimile<PHONE_NUMBER>; email [email protected].

SUPPLEMENTARY INFORMATION: Certification of the Gulfstream Model GVII-
G500 series airplanes is currently scheduled for July 2018. Because a
delay in design approval would significantly affect the certification
of the airplane and thus delivery of the airplane, we are shortening
the public-comment period to 20 days.

Comments Invited

    We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
    We will consider all comments we receive by the closing date for
comments. We may change these special conditions based on the comments
we receive.

Background

    On June 30, 2013, Gulfstream Aerospace Corporation applied for a
type certificate for its new Model GVII-G500 series airplane. The
Gulfstream Model GVII-G500 series airplane will be a business jet with
seating for up to 19 passengers. It will incorporate a low, swept-wing
design with a T-tail. The powerplant will consist of two aft-fuselage-
mounted turbofan engines. The Gulfstream Model GVII-G500 series
airplane's maximum takeoff weight will be approximately 79,600 lbs.
    The high incidence protection system prevents the airplane from
stalling at low speeds and, therefore, a stall warning system is not
needed during normal flight conditions.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.17, Gulfstream Aerospace Corporation must show that the Model
GVII-G500 series airplane meets the applicable provisions of 14 CFR
part 25, as amended by amendments 25-1 through 25-137.
    If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Gulfstream Model GVII-G500 series
airplane because of a novel or unusual design feature, special
conditions are prescribed under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, these special conditions would also apply to
the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special
conditions, the Gulfstream Model GVII-

G500 series airplanes must comply with the fuel vent and exhaust
emission requirements of 14 CFR part 34, and the noise certification
requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec.  11.38, and they become part of the type
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Gulfstream Model GVII-G500 series airplane will incorporate the
following novel or unusual design feature: A high incidence protection
system, which limits the angle of attack at which the airplane can be
flown during normal low speed operation, prohibits the airplane from
stalling, and cannot be overridden by the flightcrew. The application
of this angle of attack limit influences the stall speed determination,
stall characteristics, stall warning demonstration, and longitudinal
handling characteristics of the airplane. Existing airworthiness
regulations do not contain adequate standards to address this feature.

Discussion

    The high incidence protection system prevents the airplane from
stalling at low speeds and, therefore, a stall warning system is not
needed during normal flight conditions. However, during failures, which
are not shown to be extremely improbable, the requirements of
Sec. Sec.  25.203 and 25.207 apply, although slightly modified by these
conditions. If there are failures of the high incidence protection
system that are not shown to be extremely improbable, the flight
characteristics at the angle of attack for CLMAX must be
suitable in the traditional sense, and stall warning must be provided
in a conventional manner.
    Part I of the following special conditions is in lieu of Sec. Sec.
25.21(b), 25.103, 25.145(a), 25.145(b)(6), 25.175(c) and (d), 25.201,
25.203, 25.207, and 25.1323(d). Part II is in lieu of Sec. Sec.
25.21(g)(1), 25.105(a)(2)(i), 25.107(c) and (g), 25.121(b)(2)(ii)(A),
25.121(c)(2)(ii)(A), 25.121(d)(2)(ii), 25.123(b)(2)(i),
25.125(b)(2)(ii)(B), and 25.143(j).
    These proposed special conditions address this novel or unusual
design feature on the Gulfstream Model GVII-G500 airplane, and contain
the additional safety standards that the Administrator considers
necessary to establish a level of safety equivalent to that established
by the existing airworthiness standards.
    These proposed special conditions are different from special
conditions previously issued on this topic. In Part 1, sections
3.b.iv., 3.b.vi., 3.e.vi., 5.a.i.1., 5.a.i.4., 5.a.i.6., 5.a.i.7.,
5.c.i.4., 5.c.i.5., 5.c.i.6, 5.c.ii.4., and 5.cii.5., previously used
verbiage was updated to reflect language recommended in the ARAC Flight
Test Harmonization Working Group (FTHWG) Phase 2 report. This language
more accurately describes the actions required and formulas to be used
to obtain the required result. In Part 1, sections 3.b.ii and
5.a.ii.4., the ARAC FTHWG language was adapted to reflect specific
Gulfstream design features.
    In several previous special conditions on this subject, we used the
nomenclature VCLMAX. To avoid confusion with previous
Gulfstream special conditions, we have changed the nomenclature to
VCLMAX Demo to highlight a difference. The difference is not
significant, but the change in nomenclature was considered clarifying
and therefore was adopted in this instance.

Applicability

    As discussed above, these special conditions are applicable to the
Gulfstream Model GVII-G500 series airplanes. Should Gulfstream
Aerospace Corporation apply at a later date for a change to the type
certificate to include another model incorporating the same novel or
unusual design feature, these special conditions would apply to that
model as well.

Conclusion

    This action affects only certain novel or unusual design features
on Gulfstream Model GVII-G500 series of airplanes. It is not a rule of
general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting, and recordkeeping
requirements.

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Gulfstream Model GVII-G500 series airplanes.

Part I: Stall Protection and Scheduled Operating Speeds

    In the following sections, ``in icing conditions,'' means with ice
accretions (relative to the relevant flight phase) as defined in
appendix C to part 25, at amendment 25-121.
1. Definitions
    These special conditions use terminology that does not appear in 14
CFR part 25. For the purpose of these special conditions, the following
terms describe certain aspects of this novel or unusual design feature:
High-Incidence Protection System
    A system that operates directly and automatically on the airplane's
flight controls to limit the maximum angle of attack that can be
attained to a value below that at which an aerodynamic stall would
occur.
Alpha-Limit
    The maximum angle of attack at which an airplane stabilizes with
the high incidence protection system operating and the longitudinal
control held on its aft stop.
VMIN
    The minimum steady flight speed in the airplane's configuration
under consideration with the high incidence protection system
operating. See Part I, Section 3, ``Minimum Steady Flight Speed and
Reference Stall Speed,'' of these special conditions.
VMIN1g
    VMIN corrected to 1g acceleration of gravity conditions.
See Part I, Section 3, ``Minimum Steady Flight Speed and Reference
Stall Speed,'' of these special conditions. This is the minimum
calibrated airspeed at which the airplane can develop a lift force
normal to the flight path and equal to its weight when at an angle of
attack not greater than that determined for VMIN.
2. Capability and Reliability of the High Incidence Protection System
    The applicant must establish the capability and reliability of the
high incidence protection system. The applicant may establish this
capability and reliability by flight testing, simulation, or analysis
as appropriate. The capability and reliability required are:
    a. It must not be possible to encounter a stall during the pilot-
induced maneuvers required by Part I, section 5(a), ``High Incidence
Handling Demonstrations,'' and the handling characteristics must be
acceptable as required by Part I, section 5(b), ``Characteristics in
High Incidence Maneuvers'' of these special conditions;
    b. The airplane must be protected against stalling due to the
effects of wind shears and gusts at low speeds as required by Section
6, ``Atmospheric Disturbances'' of these special conditions;

    c. The ability of the high incidence protection system to
accommodate any reduction in stalling incidence must be verified in
icing conditions;
    d. The high incidence protection system must be provided in each
abnormal configuration of the high lift devices that is likely to be
used in flight following system failures; and
    e. The reliability of the system and the effects of failures must
be acceptable in accordance with Sec.  25.1309.
3. Minimum Steady Flight Speed and Reference Stall Speed
    In lieu of Sec.  25.103, ``Stall speed,'' the following applies:
    a. The minimum steady flight speed, VMIN, is the final,
stabilized, calibrated airspeed obtained when an airplane is
decelerated until the longitudinal control is on its stop in such a way
that the entry rate does not exceed 1 knot per second.
    b. The minimum steady flight speed, VMIN, must be
determined in icing and non-icing conditions with:
    i. The high incidence protection system operating normally;
    ii. Idle thrust;
    iii. All combinations of flap settings and landing gear positions
for which VMIN is required to be determined;
    iv. The weight used when the reference stall speed, VSR,
is used as a factor to determine compliance with a required performance
standard;
    v. The most unfavorable center of gravity (CG) allowable; and
    vi. The airplane trimmed for straight flight at a speed selected by
the applicant, but not less than 1.13 VSR and not greater
than 1.3 VSR.
    c. The 1g minimum steady flight speed, VMIN1g, is the
minimum calibrated airspeed at which an airplane can develop a lift
force (normal to the flight path) equal to its weight, while at an
angle of attack not greater than that at which the minimum steady
flight speed referenced in section 3(a) of this special condition is
determined. These minimum calibrated airspeeds must be determined for
both icing and non-icing conditions.
    d. The reference stall speed, VSR, is a calibrated
airspeed defined by the applicant. VSR may not be less than
a 1g stall speed. VSR must be determined in non-icing
conditions and expressed as:
[GRAPHIC] [TIFF OMITTED] TP14MY18.000

Where:

VCLMAX Demo = Demonstrated calibrated airspeed obtained
when the corrected lift coefficient of the load factor
[GRAPHIC] [TIFF OMITTED] TP14MY18.001

 is first a maximum during the
 maneuver prescribed in
 section 3(e)(viii)
 of this
 special condition.
nZW = Load factor normal to the flight path at
VCLMAX Demo
W = Airplane gross weight;
S = Aerodynamic reference wing area; and
q = Dynamic pressure.

    e. VCLMAX Demo is determined in non-icing conditions
with:
    i. Engines idling, or, if that resultant thrust causes an
appreciable decrease in stall speed, not more than zero thrust at the
stall speed;
    ii. The airplane in other respects (such as flaps and landing gear)
in the condition existing in the test or performance standard in which
VSR is being used;
    iii. The weight used when VSR is being used as a factor
to determine compliance with a required performance standard;
    iv. The CG position that results in the highest value of the
reference stall speed;
    v. The airplane trimmed for straight flight at a speed selected by
the applicant, but not less than 1.13 VSR and not greater
than 1.3 VSR;
    vi. At the option of the applicant, the high incidence protection
system can be disabled or adjusted to allow full development of the
maneuver to the angle of attack corresponding to VSR; and
    vii. Starting from the stabilized trim condition, with an
application of the longitudinal control to decelerate the airplane so
that the speed reduction does not exceed 1 knot per second.
4. Stall Warning
    In lieu of Sec.  25.207, the following apply:
a. Normal Operation
    If the design meets all conditions of Part I, section 2 of these
special conditions, then the airplane need not provide stall warning
during normal operation. The conditions of Part I, section 2 provide a
level of safety equal to the intent of Sec.  25.207, ``Stall warning,''
so the provision of an additional, unique warning device for normal
operations is not required.
b. High Incidence Protection System Failure
    For any failures of the high incidence protection system that the
applicant cannot show to be extremely improbable, and that result in
the capability of the system no longer satisfying any part of sections
2(a), (b), and (c) of Part I of these special conditions: The design
must provide stall warning that protects against encountering
unacceptable characteristics and against encountering stall.
    i. This stall warning, with the flaps and landing gear in any
normal position, must be clear and distinctive to the pilot, and must
meet the requirements specified in sections 4(b)(iv) and 4(b)(v) of
Part I of these special conditions.
    ii. The design must also provide this stall warning in each
abnormal configuration of the high lift devices that is likely to be
used in flight following system failures.
    iii. The design may furnish this stall warning either through the
inherent aerodynamic qualities of the airplane or by a device that will
provide clearly distinguishable indications to the flightcrew under all
expected conditions of flight. However, a visual stall warning device
that requires the attention of the flightcrew within the flight deck is
not acceptable by itself. If a warning device is used, it must provide
a warning in each of the airplane configurations prescribed in section
4(b)(i), above, and for the conditions prescribed in sections 4(b)(iv)
and 4(b)(v) of Part I of these special conditions.
    iv. In non-icing conditions, the stall warning must provide
sufficient margin to prevent encountering unacceptable characteristics
and encountering stall in the following conditions:
    1. In power-off straight deceleration not exceeding 1 knot per
second to a speed of 5 knots or 5 percent calibrated airspeed (CAS),
whichever is greater, below the warning onset; and
    2. In turning flight, stall deceleration at entry rates up to 3
knots per second when recovery is initiated not less than 1 second
after the warning onset.
    v. In icing conditions, the stall warning must provide sufficient
margin to prevent encountering unacceptable characteristics and
encountering stall in power-off straight and turning flight
decelerations not exceeding 1 knot per second, when the pilot starts a
recovery maneuver not less than three seconds after the onset of stall
warning.
    vi. An airplane is considered stalled when the behavior of the
airplane gives the pilot a clear, distinctive, and acceptable
indication that the airplane is stalled. Acceptable indications of a
stall, occurring either individually or in combination, are:
    1. A nose-down pitch that cannot be readily arrested;
    2. Buffeting of a magnitude and severity that is strong and thereby
an

effective deterrent to further speed reduction; or
    3. The pitch control reaches the aft stop, and no further increase
in pitch attitude occurs when the control is held full aft for a short
time before recovery is initiated.
    vii. An airplane exhibits unacceptable characteristics during
straight or turning flight decelerations if it is not always possible
to produce and to correct roll and yaw by unreversed use of aileron and
rudder controls, or abnormal nose-up pitching occurs.
5. Handling Characteristics at High Incidence
a. High Incidence Handling Demonstrations
    In lieu of Sec.  25.201, ``Stall demonstration,'' the following is
required:
    i. Maneuvers to the limit of the longitudinal control, in the nose-
up sense, must be demonstrated in straight flight and in 30-degree
banked turns with:
    1. The high incidence protection system operating normally;
    2. Initial power conditions of:
    a. Power off; and
    b. Power necessary to maintain level flight at 1.5 VSR1,
where VSR1 is the reference stall speed with flaps in
approach position, landing gear retracted, and maximum landing weight;
    3. None;
    4. Flaps, landing gear, and deceleration devices in any likely
combination of positions not prohibited by the airplane flight manual
(AFM);
    5. Representative weights within the range for which certification
is requested;
    6. The most adverse CG for recovery; and
    7. The airplane trimmed for straight flight at the speed prescribed
in section 3(e)(v) of these special conditions.
    ii. The following procedures must be used to show compliance in
non-icing and icing conditions:
    1. Starting at a speed sufficiently above the minimum steady flight
speed to ensure that a steady rate of speed reduction can be
established, apply the longitudinal control so that the speed reduction
does not exceed 1 knot per second until the control reaches the stop.
    2. The longitudinal control must be maintained at the stop until
the airplane has reached a stabilized flight condition, and must then
be recovered by normal recovery techniques.
    3. Maneuvers with increased deceleration rates:
    a. In non-icing conditions, the requirements must also be met with
increased rates of entry to the incidence limit, up to the maximum rate
achievable.
    b. In icing conditions, with the anti-ice system working normally,
the requirements must also be met with increased rates of entry to the
incidence limit, up to three knots per second.
    4. Maneuvers with ice accretion prior to normal operation of the
ice protection system:
    For flight in icing conditions before the ice protection system has
been activated and is performing its intended function, the handling
demonstration requirements identified in section 5(a)(i) must be
satisfied using the procedures specified in sections 5(a)(ii)(1) and
5(a)(ii)(2) of these special conditions. The airplane configurations
required to be tested must be in accordance with the limitations and
procedures for operating the ice protection system provided in the AFM,
per Sec.  25.21(g)(1), as modified by and Part II of these special
conditions.
b. Characteristics in High Incidence Maneuvers
    In lieu of Sec.  25.203, ``Stall characteristics,'' the following
apply:
    i. Throughout maneuvers with a rate of deceleration of not more
than 1 knot per second, both in straight flight and in 30-degree banked
turns, the airplane's characteristics must be as follows:
    1. There must not be any abnormal nose-up pitching;
    2. There must not be any uncommanded nose-down pitching, which
would be indicative of stall. However, reasonable attitude changes
associated with stabilizing the incidence at Alpha limit, as the
longitudinal control reaches the stop would be acceptable;
    3. There must not be any uncommanded lateral or directional motion,
and the pilot must retain good lateral and directional control by
conventional use of the controls throughout the maneuver; and
    4. The airplane must not exhibit buffeting of a magnitude and
severity that would act as a deterrent from completing the maneuver
specified in section 5(a)(i) of these special conditions.
    ii. In maneuvers with increased rates of deceleration, some
degradation of characteristics is acceptable, associated with a
transient excursion beyond the stabilized Alpha limit. However, the
airplane must not exhibit dangerous characteristics or characteristics
that would deter the pilot from holding the longitudinal control on the
stop for a period of time appropriate to the maneuver.
    iii. It must always be possible for flightcrew to reduce incidence
by conventional use of the controls.
    iv. The rate at which the airplane can be maneuvered from trim
speeds, associated with scheduled operating speeds such as
V2 and VREF up to Alpha limit, must not be unduly
damped or be significantly slower than can be achieved on
conventionally controlled transport airplanes.
c. Characteristics Up to the Maximum Lift Angle of Attack
    In addition to the requirements in section 5(b) of this special
condition, the following requirements apply:
    i. In non-icing conditions, maneuvers with a rate of deceleration
of not more than 1 knot per second, up to the angle of attack
corresponding to VSR obtained using sections 3(d) and (e) of
this special condition, must be demonstrated in straight flight and in
30-degree banked turns in the following configurations:
    1. The high incidence protection system deactivated or adjusted, at
the option of the applicant, to allow higher incidence than is possible
with the normal production system;
    2. Automatic-thrust-increase system inhibited (if applicable);
    3. Engines idling;
    4. Flaps, landing gear, and deceleration devices in any likely
combination of positions not prohibited by the AFM;
    5. The most adverse CG for recovery; and
    6. The airplane trimmed for straight flight at the speed prescribed
in section 3(e)(v) of this special condition.
    ii. In icing conditions, maneuvers with a rate of deceleration of
not more than 1 knot per second up to the maximum angle of attack
reached during maneuvers from section 5(a)(ii)(3)(b) must be
demonstrated in straight flight with:
    1. The high incidence protection system deactivated or adjusted, at
the option of the applicant, to allow higher incidence than is possible
with the normal production system;
    2. Automatic-thrust-increase system inhibited (if applicable);
    3. Engines idling;
    4. Flaps, landing gear, and deceleration devices in any likely
combination of positions not prohibited by the AFM;
    5. The most adverse CG for recovery; and
    6. The airplane trimmed for straight flight at the speed prescribed
in section 3(e)(v) of this special condition.

    iii. During the maneuvers used to show compliance with sections
5(c)(i) and 5(c)(ii) of Part I of these special conditions, the
airplane must not exhibit dangerous characteristics and it must always
be possible for flightcrew to reduce angle of attack by conventional
use of the controls. The pilot must retain good lateral and directional
control, by conventional use of the controls, throughout the maneuver.
6. Atmospheric Disturbances
    Operation of the high incidence protection system must not
adversely affect airplane control during expected levels of atmospheric
disturbances, nor impede the application of recovery procedures in case
of wind shear. This must be demonstrated in non-icing and icing
conditions.
7. None
8. Proof of Compliance
    Add the following requirement to that of Sec.  25.21:
    (b) The flying qualities will be evaluated at the most unfavorable
CG position.
9. The Design Must Meet the Following Modified Requirements

------------------------------------------------------------------------
              14 CFR  section                          Change
------------------------------------------------------------------------
25.145(a).................................  ``VMIN'' in lieu of ``stall
                                             identification''.
25.145(b)(6)..............................  ``VMIN'' in lieu of ``VSW''.
25.175(c) and (d).........................  ``VMIN'' in lieu of ``VSW''.
25.1323(d)................................  ``From 1.23 VSR to VMIN'' in
                                             lieu of ``From 1.23 VSR to
                                             the speed at which stall
                                             warning begins;'' and
                                             ``speeds below VMIN'' in
                                             lieu of ``speeds below
                                             stall warning speed.''
------------------------------------------------------------------------

Part II: Credit for Robust Envelope Protection in Icing Conditions

    1. In lieu of Sec.  25.21(g)(1), the following applies:
    (g) The requirements of this subpart associated with icing
conditions apply only if certification for flight in icing conditions
is desired. If certification for flight in icing conditions is desired,
the following requirements also apply (see AC 25-25):
    (1) Each requirement of this subpart, except Sec. Sec.  25.121(a),
25.123(c), 25.143(b)(1) and (b)(2), 25.149, 25.201(c)(2), 25.207(c) and
(d), and 25.251(b) through (e), must be met in icing conditions.
Compliance must be shown using the ice accretions defined in appendix C
to part 25, assuming normal operation of the airplane and its ice
protection system in accordance with the operating limitations and
operating procedures established by the applicant and provided in the
Airplane Flight Manual.
    2. In lieu of Sec.  25.103, ``Stall speed,'' define the stall speed
as provided in Special Conditions Part I, section 3, ``Minimum Steady
Flight Speed and Reference Stall Speed.''
    3. In lieu of Sec.  25.105(a)(2)(i) to read as follows:
    (2) In icing conditions, if in the configuration of Sec.  25.121(b)
with the ``Takeoff Ice'' accretion defined in appendix C to part 25:
    (i) the V2 speed scheduled in non-icing conditions does not provide
the maneuvering capability specified in Sec.  25.143(h) for the takeoff
configuration, or
    4. In lieu of Sec.  25.107(c) and (g), the following apply, with
additional sections (c') and (g'):
    (c) In non-icing conditions, V2, in terms of calibrated
airspeed, must be selected by the applicant to provide at least the
gradient of climb required by Sec.  25.121(b) but may not be less
than--
    1. V2MIN;
    2. VR plus the speed increment attained (in accordance
with Sec.  25.111(c)(2)) before reaching a height of 35 feet above the
takeoff surface; and
    3. A speed that provides the maneuvering capability specified in
Sec.  25.143(h).
    (c') In icing conditions with the ``Takeoff Ice'' accretion defined
in appendix C to part 25, V2 may not be less than--
    1. The V2 speed determined in non-icing conditions.
    2. A speed that provides the maneuvering capability specified in
Sec.  25.143(h).
    (g) In non-icing conditions, VFTO, in terms of
calibrated airspeed, must be selected by the applicant to provide at
least the gradient of climb required by Sec.  25.121(c), but may not be
less than--
    1. 1.18 VSR; and
    2. A speed that provides the maneuvering capability specified in
Sec.  25.143(h).
    (g') In icing conditions with the ``Final Takeoff Ice'' accretion
defined in appendix C to part 25, VFTO may not be less
than--
    1. The VFTO speed determined in non-icing conditions.
    2. A speed that provides the maneuvering capability specified in
Sec.  25.143(h).
    5. In lieu of Sec. Sec.  25.121(b)(2)(ii)(A), 25.121(c)(2)(ii)(A),
and 25.121(d)(2)(ii), the following apply:
    Sec.  25.121 Climb: One-engine inoperative:
    (b) Takeoff; landing gear retracted. In the takeoff configuration
existing at the point of the flight path at which the landing gear is
fully retracted, and in the configuration used in Sec.  25.111, but
without ground effect,
    * * *
    2. The requirements of subparagraph (b)(1) of this section must be
met:
    * * *
    (ii) In icing conditions with the ``Takeoff Ice'' accretion defined
in appendix C of part 25, if in the configuration of Sec.  25.121(b)
with the ``Takeoff Ice'' accretion:
    (A) The V2 speed scheduled in non-icing conditions does
not provide the maneuvering capability specified in Sec.  25.143(h) for
the takeoff configuration; or
    (c) Final takeoff. In the en route configuration at the end of the
takeoff path determined in accordance with Sec.  25.111:
    * * *
    2. The requirements of subparagraph (c)(1) of this section must be
met:
    * * *
    (ii) In icing conditions with the ``Final Takeoff Ice'' accretion
defined in appendix C of part 25, if:
    (A) The VFTO speed scheduled in non-icing conditions
does not provide the maneuvering capability specified in Sec.
25.143(h) for the en route configuration; or
    (d) Approach. In a configuration corresponding to the normal all-
engines operating procedure in which VSR for this
configuration does not exceed 110 percent of the VSR for the
related all-engines-operating landing configuration:
* * * * *
    2. The requirements of sub-paragraph (d)(1) of this section must be
met:
* * * * *
    (ii) In icing conditions with the ``Approach Ice'' accretion
defined in appendix C to part 25, in a configuration corresponding to
the normal all-engines-operating procedure in which VMIN1g
for this configuration does not exceed 110% of the VMIN1g
for the related all engines-operating landing configuration in icing,
with a climb speed established with normal landing procedures, but not
more than 1.4 VSR (VSR determined in non-icing
conditions).
    6. In lieu of Sec.  25.123 (b)(2)(i), the following applies:
    Sec.  25.123 En route flight paths:
    (b) The one-engine-inoperative net flight path data must represent
the actual climb performance diminished by a gradient of climb of 1.1
percent for two-engine airplanes, 1.4 percent for three-engine
airplanes, and 1.6 percent for four-engine airplanes.
* * * * *
    2. In icing conditions with the ``En route Ice'' accretion defined
in appendix C to part 25 if:

    (i) The minimum en route speed scheduled in non-icing conditions
does not provide the maneuvering capability specified in Sec.
25.143(h) for the en route configuration, or
    7. In lieu of Sec.  25.125(b)(2)(ii)(B) and Sec.
25.125(b)(2)(ii)(C), the following applies:
    Sec.  25.125 Landing.
    (b) In determining the distance in (a):
* * * * *
    2. A stabilized approach, with a calibrated airspeed of not less
than VREF, must be maintained down to the 50-foot height.
* * * * *
    (ii) In icing conditions, VREF may not be less than:
    (A) The speed determined in sub-paragraph (b)(2)(i) of this
section;
    (B) A speed that provides the maneuvering capability specified in
Sec.  25.143(h) with the ``Landing Ice'' accretion defined in appendix
C to part 25.
    8. In lieu of Sec.  25.143(j), the following applies:
    Sec.  25.143 General.
    (j) For flight in icing conditions--before the ice protection
system has been activated and is performing its intended function--the
following requirements apply:
    (1) If activating the ice protection system depends on the pilot
seeing a specified ice accretion on a reference surface (not just the
first indication of icing), the requirements of Sec.  25.143 apply with
the ice accretion defined in part II(e) of appendix C to part 25.
    (2) For other means of activating the ice protection system, it
must be demonstrated in flight with the ice accretion defined in part
II(e) of appendix C to part 25 that:
    (i) The airplane is controllable in a pull-up maneuver up to 1.5 g
load factor or lower if limited by AOA protection; and
    (ii) There is no reversal of pitch control force during a pushover
maneuver down to 0.5 g load factor.
    9. In lieu of Sec.  25.207, ``Stall warning,'' to read as the
requirements defined in Part I of these special conditions.

    Issued in Renton, Washington, on May 8, 2018.
Victor Wicklund,
Manager, Transport Standards Branch, Policy and Innovation Division,
Aircraft Certification Service.
[FR Doc. 2018-10168 Filed 5-11-18; 8:45 am]
 BILLING CODE 4910-13-P