[Federal Register Volume 80, Number 159 (Tuesday, August 18, 2015)]
[Proposed Rules]
[Pages 49936-49938]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-20297]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2015-1482; Notice No. 25-15-08-SC]
Special Conditions: Gulfstream Model GVII-G500 Airplanes,
Automatic Speed Protection for Design Dive Speed
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
Model GVII-G500 airplanes. These airplanes will have a novel or unusual
design feature associated with a reduced margin between design cruising
speed, VC/MC, and design diving speed,
VD/MD, based on the incorporation of a high-speed
protection system that limits nose-down pilot authority at speeds above
VC/MC. The applicable airworthiness regulations
do not contain adequate or appropriate safety standards for this design
feature. These proposed 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 October 2, 2015.
ADDRESSES: Send comments identified by docket number FAA-2015-1482
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 202-493-2251.
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 Web site, 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), as well as at http://DocketsInfo.dot.gov/.
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: Walt Sippel, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-2774; facsimile 425-227-1232.
SUPPLEMENTARY INFORMATION:
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 March 29, 2012, Gulfstream Aerospace Corporation applied for a
type certificate for their new Model GVII-G500 airplane. The Model
GVII-G500 airplane will be a large-cabin business jet with seating for
19 passengers. It will incorporate a low, swept-wing design with
winglets and a T-tail. The powerplant will consist of two aft-fuselage-
mounted Pratt & Whitney turbofan engines. Avionics will include four
primary display units and multiple touchscreen controllers. The flight-
control system is a three-axis, fly-by-wire system incorporating active
control/coupled side sticks.
The Model GVII-G500 will have a wingspan of approximately 87 feet
and a length of just over 91 feet. Maximum takeoff weight will be
approximately 76,850 pounds and maximum takeoff thrust will be
approximately 15,135 pounds. Maximum range will be
[[Page 49937]]
approximately 5,000 nautical miles, and maximum operating altitude will
be 51,000 feet.
Type Certification Basis
Under the provisions ofTitle 14, Code of Federal Regulations (14
CFR) 21.17, Gulfstream must show that the Model GVII-G500 airplane
meets the applicable provisions of part 25 as amended by Amendments 25-
1 through 25-137.
In addition, the certification basis includes other regulations,
special conditions, and exemptions that are not relevant to these
proposed special conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for Model GVII-G500 airplanes 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, the special conditions would also apply to the
other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Model GVII-G500 airplane 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; and the FAA must issue a
finding of regulatory adequacy under Sec. 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 Model GVII-G500 airplane will incorporate the following novel
or unusual design features:
Gulfstream proposes to reduce the margin between VC/
MC and VD/MD, required by 14 CFR
25.335(b), based on the incorporation of a high-speed protection system
in the airplane's flight-control laws. The high-speed protection system
limits nose-down pilot authority at speeds above VC/
MC, and prevents the airplane from performing the maneuver
required under Sec. 25.335(b)(1).
These proposed 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.
Discussion
Title 14, Code of Federal Regulations (14 CFR) 25.335(b)(1) is an
analytical envelope condition which was originally adopted in Part 4b
of the Civil Air Regulations to provide an acceptable speed margin
between design cruise speed and design dive speed. Flutter clearance
design speeds and airframe design loads are impacted by the design dive
speed. While the initial condition for the upset specified in the rule
is 1g level flight, protection is afforded for other inadvertent
overspeed conditions as well. Section 25.335(b)(1) is intended as a
conservative enveloping condition for potential overspeed conditions,
including non-symmetric ones. To establish that potential overspeed
conditions are enveloped, Gulfstream must demonstrate that any reduced
speed margin based on the high-speed protection system in the Model
GVII-G500 airplane will not be exceeded in inadvertent or gust-induced
upsets resulting in initiation of the dive from non-symmetric
attitudes; or that the airplane is protected by the flight-control laws
from getting into non-symmetric upset conditions. Gulfstream must
conduct a demonstration that includes a comprehensive set of conditions
as described below.
These special conditions are proposed in lieu of Sec.
25.335(b)(1). Section 25.335(b)(2), which also addresses the design
dive speed, is applied separately (Advisory Circular (AC) 25.335-1A
provides an acceptable means of compliance to Sec. 25.335(b)(2)).
Special conditions are necessary to address the Model GVII-G500
airplane high-speed protection system.These proposed special conditions
identify various symmetric and non-symmetric maneuvers that will ensure
that an appropriate design dive speed, VD/MD, is
established.
Special Condition 2 of these proposed special conditions references
AC 25-7C, section 8, paragraph 32, ``Gust Upset,'' included here for
reference:
In the following three upset tests, the values of displacement
should be appropriate to the airplane type and should depend upon
airplane stability and inertia characteristics. The lower and upper
limits should be used for airplanes with low and high maneuverability,
respectively.
(i) With the airplane trimmed in wings-level flight, simulate a
transient gust by rapidly rolling to the maximum bank angle appropriate
for the airplane, but not less than 45 degrees nor more than 60
degrees. The rudder and longitudinal control should be held fixed
during the time that the required bank is being attained. The rolling
velocity should be arrested at this bank angle. Following this, the
controls should be abandoned for a minimum of 3 seconds after
VMO/MMO, or after 10 seconds, whichever occurs
first.
(ii) Perform a longitudinal upset from normal cruise. Airplane trim
is determined at VMO/MMO using power and thrust
required for level flight, but with not more than maximum continuous
power and thrust. This is followed by a decrease in speed, after which
an attitude of 6 to l2 degrees nose down, as appropriate for the
airplane type, is attained with the power, thrust, and trim initially
required for VMO/MMO in level flight. The
airplane is permitted to accelerate until 3 seconds after
VMO/MMO. The force limits of Sec. 25.143(d) for
short term application apply.
(iii) Perform a two-axis upset, consisting of combined longitudinal
and lateral upsets. Perform the longitudinal upset, as in paragraph
(ii) above, and when the pitch attitude is set, but before reaching
VMO/MMO, roll the airplane to between 15 and 25
degrees. The established attitude should be maintained until 3 seconds
after VMO/MMO.
Special Conditions 3 and 4 of these proposed special conditions
indicate that failures of the high-speed protection system must be
improbable and must be annunciated to the pilots. If these two criteria
are not met, then the probability that the established dive speed will
be exceeded, and the resulting risk to the airplane, are too great. On
the other hand, if the high-speed protection system is known to be
inoperative, then dispatch of the airplane may be acceptable as allowed
by proposed Special Condition 5. Dispatch would only be acceptable if
appropriate reduced operating speeds, VMO/MMO, as
well as the overspeed warning for exceeding those speeds, are provided
in both the airplane flight manual and on the flightdeck display, and
are equivalent to that of the normal airplane with the high-speed
protection system operative.
We do not believe that application of the ``Interaction of Systems
and Structures'' Special Conditions (reference GVI Issue Paper A-2), or
EASA Certification Specification 25.302, are appropriate in this case,
because design dive speed is, in and of itself, part of the design
criteria. Stability and control, flight loads, and flutter evaluations
all depend on the design dive speed. Therefore, a single design dive
speed should be established
[[Page 49938]]
that will not be exceeded, taking into account the performance of the
high-speed protection system as well as its failure modes, failure
indications, and accompanying flight-manual instructions.
Applicability
As discussed above, these special conditions are applicable to the
Model GVII-G500 airplane. 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 feature, the special conditions would
apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model of airplane. 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 Proposed Special Conditions
0
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Gulfstream Model GVII-G500 airplanes.
1. In lieu of compliance with Sec. 25.335(b)(1), if the flight-
control system includes functions that act automatically to initiate
recovery before the end of the 20-second period specified in Sec.
25.335(b)(1), VD/MD must be determined from the
greater of the speeds resulting from conditions (a) and (b) of these
special cConditions. The speed increase occurring in these maneuvers
may be calculated if reliable or conservative aerodynamic data are
used.
(a) From an initial condition of stabilized flight at
VC/MC, the airplane is upset so as to take up a
new flight path 7.5 degrees below the initial path. Control
application, up to full authority, is made to try to maintain this new
flight path. Twenty seconds after initiating the upset, manual recovery
is made at a load factor of 1.5g (0.5 acceleration increment), or such
greater load factor that is automatically applied by the system with
the pilot's pitch control neutral. Power, as specified in Sec.
25.175(b)(1)(iv), is assumed until recovery is initiated, at which time
power reduction, and the use of pilot-controlled drag devices, may be
used.
(b) From a speed below VC/MC, with power to
maintain stabilized level flight at this speed, the airplane is upset
so as to accelerate through VC/MC at a flight
path 15 degrees below the initial path (or at the steepest nose-down
attitude that the system will permit with full control authority if
less than 15 degrees). The pilot's controls may be in the neutral
position after reaching VC/MC and before recovery
is initiated. Recovery may be initiated 3 seconds after operation of
the high-speed warning system by application of a load of 1.5g (0.5
acceleration increment), or such greater load factor that is
automatically applied by the system with the pilot's pitch control
neutral. Power may be reduced simultaneously. All other means of
decelerating the airplane, the use of which is authorized up to the
highest speed reached in the maneuver, may be used. The interval
between successive pilot actions must not be less than 1 second.
2. The applicant must also demonstrate that the speed margin,
established as above, will not be exceeded in inadvertent or gust-
induced upsets resulting in initiation of the dive from non-symmetric
attitudes, unless the airplane is protected by the flight-control laws
from getting into non-symmetric upset conditions. The upset maneuvers
described in Advisory Circular 25-7C, ``Flight Test Guide for
Certification of Transport Category Airplanes,'' section 8, paragraph
32, sub-paragraphs c(3)(a), (b), and (c), may be used to comply with
this requirement.
3. The probability of any failure of the high-speed protection
system, which would result in an airspeed exceeding those determined by
Special Conditions 1 and 2, must be less than 10-5 per
flight hour.
4. Failures of the system must be annunciated to the pilots. Flight
manual instructions must be provided that reduce the maximum operating
speeds, VMO/MMO. With the system failed, the
operating speed must be reduced to a value that maintains a speed
margin between VMO/MMO and VD/
MD, and that is consistent with showing compliance with
Sec. 25.335(b) without the benefit of the high-speed protection
system.
5. The applicant may request that the Master Minimum Equipment List
relief for the high-speed protection system be considered by the FAA
Flight Operations Evaluation Board, provided that the flight manual
instructions indicate reduced maximum operating speeds as described in
Special Condition 4. In addition, the flightdeck display of the reduced
operating speeds, as well as the overspeed warning for exceeding those
speeds, must be equivalent to that of the normal airplane with the
high-speed protection system operative. Also, the applicant must show
that no additional hazards are introduced with the high-speed
protection system inoperative.
Issued in Renton, Washington, on August 5, 2015.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate Aircraft Certification
Service.
[FR Doc. 2015-20297 Filed 8-17-15; 8:45 am]
BILLING CODE 4910-13-P