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[Federal Register Volume 80, Number 192 (Monday, October 5, 2015)]
[Rules and Regulations]
[Pages 60028-60030]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-25275]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-1482; Special Conditions No. 25-600-SC]

Special Conditions: Gulfstream Model GVII-G500 Airplanes, 
Automatic Speed Protection for Design Dive Speed

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Gulfstream Model 
GVII-G500 airplane. This airplane will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport-category airplanes.
    This design feature is 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 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 November 4, 2015.

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:

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.
    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 approximately 5,000 
nautical miles, and maximum operating altitude will be 51,000 feet.

Type Certification Basis

    Under the provisions of Title 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 
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

[[Page 60029]]

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 Gulfstream Model GVII-G500 airplane will incorporate the 
following novel or unusual design feature:
    For this airplane, Gulfstream will 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).

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 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 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 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 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 Special Condition 5 of these special conditions. 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 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.
    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.

Discussion of Comments

    Notice of proposed special conditions no. 25-15-08-SC for the 
Gulfstream Model GVII-G500 airplane was published in the Federal 
Register on August 18, 2015 [80 FR 49936]. No comments were received, 
and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Gulfstream 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.

0
The authority citation for these special conditions is as follows:

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

[[Page 60030]]

The Special Conditions

0
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 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 conditions. 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, September 25, 2015.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-25275 Filed 10-2-15; 8:45 am]
 BILLING CODE 4910-13-P
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