[Federal Register Volume 76, Number 59 (Monday, March 28, 2011)]
[Rules and Regulations]
[Pages 17022-17025]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-7144]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM438 Special Conditions No. 25-423-SC]


Special Conditions: Gulfstream Model GVI Airplane; High Incidence 
Protection

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Gulfstream GVI 
airplane. This airplane will have novel or unusual design features when 
compared to the state of technology envisioned in the airworthiness 
standards for transport category airplanes associated with the use of 
high incidence protection. The applicable airworthiness regulations do 
not contain adequate or appropriate safety standards for these design 
features. 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: Effective Date: April 27, 2011.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and Flight 
Crew Interface Branch, ANM-111, Transport Standards Staff, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue, 
SW., Renton, Washington 98057-3356; telephone (425) 227-2011; facsimile 
(425) 227-1320.

SUPPLEMENTARY INFORMATION:

Background

    On March 29, 2005, Gulfstream Aerospace Corporation (hereafter 
referred to as ``Gulfstream'') applied for an FAA type certificate for 
its new Gulfstream Model GVI passenger airplane. Gulfstream later 
applied for, and was granted, an extension of time for the type 
certificate, which changed the effective application date to September 
28, 2006. The Gulfstream Model GVI airplane will be an all-new, two-
engine jet transport airplane with an executive cabin interior. The 
maximum takeoff weight will be 99,600 pounds, with a maximum passenger 
count of 19 passengers.

Type Certification Basis

    Under provisions of Title 14 Code of Federal Regulations (14 CFR) 
21.17, Gulfstream must show that the Gulfstream Model GVI airplane 
(hereafter referred to as ``the GVI'') meets the applicable provisions 
of 14 CFR part 25, as amended by Amendments 25-1 through 25-119, 25-122 
and 25-124. 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 GVI 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 features, the special conditions would also apply to the 
other model under the provisions of Sec.  21.101.
    In addition to complying with the applicable airworthiness 
regulations and special conditions, the GVI 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 must also issue a 
finding of regulatory adequacy pursuant to section 611 of Public Law 
92-574, the ``Noise Control Act of 1972.''
    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 GVI is equipped with a novel or unusual design feature: A high 
incidence protection system that replaces the stall warning system 
during normal operating conditions, prohibits the airplane from 
stalling, limits the angle of attack at which the airplane can be flown 
during normal low speed operation, and cannot be overridden by the 
flight crew. The system's application of this angle of attack limit 
impacts the stall speed determination, the stall characteristics, the 
stall warning demonstration, and the longitudinal airplane handling 
characteristics. The current regulations, including Sec. Sec.  25.103, 
25.145, 25.201, 25.203, 25.207 and 25.1323, do not address this type of 
protection feature.

Discussion

    These special conditions, which include airplane performance 
requirements, will establish a level of

[[Page 17023]]

safety equivalent to the current regulations for reference stall 
speeds, stall warning, stall characteristics, and miscellaneous other 
minimum reference speeds.

Discussion of Comments

    Notice of proposed special conditions No. 25-10-03-SC for 
Gulfstream GVI airplanes was published in the Federal Register on 
December 23, 2010 (75 FR 80735). One supportive comment was received.

Applicability

    As discussed above, these special conditions are applicable to the 
high incidence protection system on the GVI. Should Gulfstream apply at 
a later date for a change to the type certificate to include another 
model incorporating the same novel or unusual design features, these 
special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
of the GVI. 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(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Gulfstream GVI airplanes.
    1. Definitions. For terminology that does not appear in the 
regulations, the following definitions apply to these special 
conditions:
    (a) Electronic Flight Control System (EFCS)--The electronic and 
software command and control elements of the flight control system.
    (b) High Incidence Protection Function--An airplane level function 
that automatically limits the maximum angle of attack that can be 
attained to a value below that at which an aerodynamic stall would 
occur.
    (c) Alpha-Limit--The maximum angle of attack at which the airplane 
stabilizes with the high incidence protection function operating and 
the longitudinal control held on its aft stop.
    (d) Vmin--The minimum stabilized flight speed in calibrated 
airspeed obtained when the airplane is decelerated at an entry rate not 
exceeding 1 knot/sec until the longitudinal pilot control is on the aft 
stop with the high incidence protection function operating.
    (e) Vmin1g--Vmin corrected to 1g conditions. 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--In lieu of Sec. Sec.  25.103, 25.145, 25.201, 25.203, 25.207 
and 25.1323, the following special conditions are issued for capability 
and reliability requirements:
    (a) It must not be possible during pilot-induced maneuvers to 
encounter a stall, and handling characteristics must be acceptable as 
required by paragraphs 5 and 6 of this special condition.
    (b) The airplane must be protected against stalling due to the 
effects of environmental conditions such as windshear and gusts at low 
speeds as required by paragraph 7 of this special condition.
    (c) The ability of the high incidence protection function to 
accommodate any reduction in stalling angle of attack resulting from 
flight in the atmospheric icing conditions of 14 CFR part 25, appendix 
C, must be verified.
    (d) The reliability of the high incidence protection function and 
the effects of failures must be acceptable in accordance with Sec.  
25.1309.
    (e) The high incidence protection function must not impede 
maneuvering for pitch angles up to the maximum required for normal 
maneuvering including an all-engines operating takeoff plus a suitable 
margin to allow for satisfactory speed control.
    3. Minimum Steady Flight Speed and Reference Stall Speed--In lieu 
of the requirements of Sec.  25.103, the following special condition is 
issued:
    (a) Vmin--The minimum steady flight speed, for the airplane 
configuration under consideration and with the high incidence 
protection function operating, is the final stabilized calibrated 
airspeed obtained when the airplane is decelerated at an entry rate not 
exceeding 1 knot per second until the longitudinal pilot control is on 
its stop.
    (b) The minimum steady flight speed, Vmin, must be determined with:
    (1) The high incidence protection function operating normally.
    (2) Idle thrust.
    (3) All combinations of flap settings and landing gear positions.
    (4) The weight used when V<INF>SR</INF> is being used as a factor 
to determine compliance with a required performance standard.
    (5) The most unfavorable center of gravity allowable.
    (6) The airplane trimmed for straight flight at a speed selected by 
the applicant, but not less than 1.13 V<INF>SR</INF> and not greater 
than 1.3 V<INF>SR</INF>.
    (7) The settings of the high incidence protection function, stall 
warning system, and stall identification system (if applicable) set at 
the low angle of attack tolerance limit, unless the production 
tolerances are acceptably small so as to produce insignificant changes 
in performance determinations.
    (c) Vmin1g--Vmin corrected to 1g conditions, which 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. Vmin1g is defined as 
follows:
[GRAPHIC] [TIFF OMITTED] TR28MR11.007

Where:

n<INF>ZW</INF> = load factor normal to the flight path at 
V<INF>min</INF>.

    (d) The reference stall speed, V<INF>SR</INF>, is a calibrated 
airspeed selected by the applicant. V<INF>SR</INF> may not be less than 
a 1g stall speed. V<INF>SR</INF> is expressed as:

[[Page 17024]]

[GRAPHIC] [TIFF OMITTED] TR28MR11.008

    (e) V<INF>SR</INF> must be determined with the following 
conditions:
    (1) Engines idling, or, if that resultant thrust causes an 
appreciable decrease in stall speed, not more than zero thrust at the 
stall speed.
    (2) The airplane in other respects (such as flaps and landing gear) 
in the condition existing in the test or performance standard in which 
V<INF>SR</INF> is being used.
    (3) The weight used when V<INF>SR</INF> is being used as a factor 
to determine compliance with a required performance standard.
    (4) The center of gravity position that results in the highest 
value of reference stall speed.
    (5) The airplane trimmed for straight flight at a speed selected by 
the applicant, but not less than 1.13 V<INF>SR</INF> and not greater 
than 1.3 V<INF>SR</INF>.
    (f) The flight characteristics at the angle of attack corresponding 
to V<INF>SR</INF> must be suitable in the traditional sense at forward 
and aft center of gravity in straight and turning flight at IDLE power.
    (g) If V<INF>SR</INF> is chosen equal to V<INF>MIN,1g</INF>, an 
equivalent safety finding to the intent of Sec.  25.103 may be 
considered to have been met. The applicant may choose V<INF>SR</INF> to 
be less than V<INF>MIN,1g</INF> but not less than V<INF>S1g</INF> if 
compensating factors are provided to ensure safe characteristics.
    4. Stall Warning
    (a) Normal Operation--If the conditions of paragraph 2 of this 
special condition are satisfied, a level of safety equivalent to that 
intended by Sec.  25.207, Stall warning, will have been met.
    (b) Failure Cases--Following failures of the high incidence 
protection function not shown to be extremely improbable, if the 
function no longer satisfies paragraphs 2(a), 2(b), and 2(c) of this 
special condition, stall warning must be provided in accordance with 
Sec.  25.207. The stall warning should prevent inadvertent stall in the 
following conditions:
    (1) Power off straight stall approaches to a speed 5 percent below 
the warning onset.
    (2) Turning flight stall approaches with at least 1.5g load factor 
normal to the flight path at an entry rate of at least 2 knots per 
second when recovery is initiated not less than one second after the 
warning onset.
    5. High Incidence Handling Demonstrations--In lieu of the 
requirements of Sec.  25.201, the following special condition are 
issued:
    (a) Maneuvers to the limit of the longitudinal control, in the nose 
up direction, must be demonstrated in straight flight and in 30 degree 
banked turns under the following conditions:
    (1) The high incidence protection function operating normally.
    (2) Power off.
    (3) At a power level necessary to maintain level flight at 1.5 
V<INF>SR1</INF>, where V<INF>SR1</INF> is the reference stall speed 
with the flaps in the approach position, the landing gear retracted, 
and with the aircraft at its maximum landing weight. The flap position 
to be used to determine this power setting is that position in which 
the stall speed, V<INF>SR1</INF>, does not exceed 110% of the stall 
speed, V<INF>SR0</INF>, with the flaps in the most extended landing 
position.
    (b) In each condition required by paragraph (a) of this section, it 
must be possible to meet the applicable requirements of Sec.  25.203 
defined in paragraph 6 of this special condition with:
    (1) Flaps, landing gear, and deceleration devices in any likely 
combination of positions not prohibited.
    (2) Deceleration devices include spoilers and other drag devices 
when used as air brakes, and thrust reversers. High incidence maneuver 
demonstrations with deceleration devices deployed should be carried out 
with power off except where power is normally applied during operations 
(e.g., use of extended airbrakes during landing).
    (3) Representative weights within the range for which certification 
is requested.
    (4) The most adverse center of gravity.
    (5) The airplane trimmed for straight flight at the speed 
prescribed in paragraph 3(e)(5) of this special condition.
    (6) The settings of the high incidence protection function, stall 
warning system, and stall identification system (if applicable) set at 
the high angle of attack tolerance limit, unless the production 
tolerances are acceptably small so as to produce insignificant changes 
in performance determinations.
    (c) The following procedures must be used to show compliance with 
Sec.  25.203 as amended by paragraph 6 of this special condition:

[[Page 17025]]

    (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 one 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 then 
recovered by normal recovery techniques.
    (3) The requirements for turning flight maneuver demonstrations 
must also be met with accelerated rates of entry to the incidence 
limit, up to the maximum rate achievable.
    6. Characteristics in High Incidence Maneuvers--In lieu of the 
requirements of Sec.  25.203, the following special condition is 
issued:
    (a) 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) No abnormal airplane nose-up pitching.
    (2) No uncommanded nose-down pitching (which is indicative of 
stall). However, reasonable attitude changes associated with 
stabilizing the incidence at alpha limit as the longitudinal control 
reaches the stop is acceptable. Any reduction of pitch attitude 
associated with stabilizing the incidence at the alpha limit should be 
achieved smoothly and at a low pitch rate, so it is not likely to be 
mistaken for natural stall identification.
    (3) No uncommanded lateral or directional motion, and the pilot 
must retain good lateral and directional control by conventional use of 
the cockpit controls throughout the maneuver.
    (4) The airplane must not exhibit buffeting of a magnitude or 
severity that would act as a deterrent to completing the maneuver 
specified in Sec.  25.201(a) as amended by this special condition.
    (b) In maneuvers with increased rates of deceleration, some 
degradation of characteristics associated with a transient excursion 
beyond the stabilized alpha-limit is acceptable. However, the airplane 
must not exhibit dangerous characteristics or characteristics that 
would deter the pilot from holding the longitudinal control on the aft 
stop for a period of time appropriate to the maneuvers.
    (c) It must always be possible to reduce incidence by conventional 
use of the longitudinal control.
    (d) The rate at which the airplane can be maneuvered from trim 
speeds associated with scheduled operating speeds, such as 
V<INF>2</INF> and V<INF>REF</INF> up to alpha-limit, should not be 
unduly damped or significantly slower than can be achieved on 
conventionally controlled transport airplanes.
    7. Atmospheric Disturbances--Operation of the high incidence 
protection function must not adversely affect aircraft control during 
expected levels of atmospheric disturbances, nor impede the application 
of recovery procedures in case of windshear. Simulator tests and 
analysis may be used to evaluate such conditions, but must be validated 
by limited flight testing to confirm handling qualities at critical 
loading conditions.
    8. Longitudinal Control--In lieu of the requirements of Sec.  
25.145(a), (a)(1) and (b)(6), the following special conditions are 
issued:
    (a) It must be possible, at any point between the trim speed 
prescribed in Sec.  25.103(b)(6) as amended by this special condition 
and Vmin, to pitch the nose downward so that the acceleration to this 
selected trim speed is prompt.
    (b) With the landing gear extended, no change in trim control, or 
exertion of more than 50 pounds control force (representative of the 
maximum short-term force that can be applied readily by one hand) may 
be required for the following maneuver: With power off, flaps extended 
and the airplane trimmed at 1.3 V<INF>SR1</INF>, obtain and maintain 
airspeeds between Vmin and either 1.6V<INF>SR1</INF> or V<INF>FE</INF>, 
whichever is lower.
    9. Airspeed Indicating System--In lieu of Sec.  25.1323(c)(1) and 
(c)(2), the following special conditions are issued:
    (a) VMO to Vmin with the flaps retracted; and
    (b) Vmin to VFE with flaps in the landing position.

    Issued in Renton, Washington, on March 18, 2011.
KC Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-7144 Filed 3-25-11; 8:45 am]
BILLING CODE 4910-13-P