[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 VSR 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 VSR and not greater
than 1.3 VSR.
(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:
nZW = load factor normal to the flight path at
Vmin.
(d) The reference stall speed, VSR, is a calibrated
airspeed selected by the applicant. VSR may not be less than
a 1g stall speed. VSR is expressed as:
[[Page 17024]]
[GRAPHIC] [TIFF OMITTED] TR28MR11.008
(e) VSR 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
VSR is being used.
(3) The weight used when VSR 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 VSR and not greater
than 1.3 VSR.
(f) The flight characteristics at the angle of attack corresponding
to VSR must be suitable in the traditional sense at forward
and aft center of gravity in straight and turning flight at IDLE power.
(g) If VSR is chosen equal to VMIN,1g, an
equivalent safety finding to the intent of Sec. 25.103 may be
considered to have been met. The applicant may choose VSR to
be less than VMIN,1g but not less than VS1g 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
VSR1, where VSR1 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, VSR1, does not exceed 110% of the stall
speed, VSR0, 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
V2 and VREF 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 VSR1, obtain and maintain
airspeeds between Vmin and either 1.6VSR1 or VFE,
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