Special Conditions: Gulfstream Model GVI Airplane; Interaction of Systems and Structures, 8316-8319 [2011-3215]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 76, Number 30 (Monday, February 14, 2011)]
[Proposed Rules]
[Pages 8316-8319]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-3215]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM442 Special Conditions No. 25-11-02-SC]


Special Conditions: Gulfstream Model GVI Airplane; Interaction of 
Systems and Structures

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 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. These design features 
include systems that affect the structural capability of the airplane. 
The applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. The 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: We must receive your comments by March 31, 2011.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. NM442, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356. You may deliver two copies to the Transport 
Airplane Directorate at the above address. You must mark your comments: 
Docket No. NM442. You can inspect comments in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Carl Niedermeyer, FAA, Airframe/Cabin 
Safety Branch, ANM-115, Transport Standards Staff, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW., 
Renton, Washington 98057-3356; telephone (425) 227-2279; facsimile 
(425) 227-1320.

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 ask 
that you send us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. You can inspect the docket before 
and after the comment closing date. If you wish to review the docket in 
person, go to the address in the ADDRESSES section of this preamble 
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions based on the comments we receive.
    If you want us to acknowledge receipt of your comments on this 
proposal, include with your comments a self-addressed, stamped postcard 
on which you have written the docket number. We will stamp the date on 
the postcard and mail it back to you.

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.
    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).
    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 provisions of Sec.  21.101.

Novel or Unusual Design Features

    The Model GVI airplane will incorporate novel or unusual design 
features. These features are systems that may affect the airplane's 
structural performance, either directly or as a result of failure or 
malfunction. That is, the airplane's systems affect how it responds in 
maneuver and gust conditions, and thereby affect its structural 
capability. These systems may also affect the aeroelastic stability of 
the airplane. These systems include the GVI's flight control systems, 
autopilots, stability augmentation systems, load alleviation systems, 
and fuel management systems. Such systems represent a novel and unusual 
feature when compared to the technology envisioned in the current 
airworthiness standards.

Discussion of Proposed Special Conditions

    Special conditions are needed to require consideration of the 
effects of systems on the structural capability and aeroelastic 
stability of the airplane, both in the normal and in the failed state, 
because these effects are not covered by current regulations.
    These proposed special conditions are identical or nearly identical 
to those previously required for type certification of other transport 
airplane models. These proposed special conditions were derived 
initially from standardized requirements developed by the Aviation 
Rulemaking Advisory Committee (ARAC), comprised of representatives of 
the FAA, Europe's Joint Aviation Authorities (now replaced by the 
European Aviation Safety Agency), and industry.

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    These proposed special conditions require that the airplane meets 
the structural requirements of subparts C and D of 14 CFR part 25 when 
the airplane systems are fully operative. These proposed special 
conditions also require that the airplane meet these requirements 
considering failure conditions. In some cases, reduced margins are 
allowed for failure conditions based on system reliability.
    These special conditions establish a level of safety that neither 
raises nor lowers the standard set forth in the applicable regulations.
    In these proposed special conditions and in the current standards 
and regulations, the term ``any'' is used. Use of this term has 
traditionally been understood to require all items covered by the term 
are addressed, rather than addressing only a portion of the items. The 
use of the term ``any'' in these proposed special conditions continues 
this traditional understanding.

Applicability

    As discussed above, these proposed special conditions are 
applicable to 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 proposed 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 this special condition is as follows:

    Authority: 49 U.S.C. 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 the GVI airplanes.

A. General

    The GVI is equipped with systems that affect structural 
performance, either directly or as a result of a failure or 
malfunction. The influence of these systems and their failure 
conditions on structural performance must be taken into account when 
showing compliance with the requirements of Subparts C and D of part 25 
of Title 14, Code of Federal Regulations.
    1. The following criteria must be used for showing compliance with 
this proposed special condition for airplanes equipped with flight 
control systems, autopilots, stability augmentation systems, load 
alleviation systems, fuel management systems, and other systems that 
either directly or as a result of failure or malfunction affect 
structural performance.
    2. The criteria defined herein only address the direct structural 
consequences of the system responses and performance. They cannot be 
considered in isolation but should be included in the overall safety 
evaluation of the airplane. These criteria may in some instances 
duplicate standards already established for this evaluation. These 
criteria are only applicable to structure whose failure could prevent 
continued safe flight and landing. Specific criteria that define 
acceptable limits on handling characteristics or stability requirements 
when operating in the system degraded or inoperative mode are not 
provided in this proposed special condition.
    3. Depending upon the specific characteristics of the airplane, 
additional studies may be required that go beyond the criteria provided 
in this proposed special condition in order to demonstrate the 
capability of the airplane to meet other realistic conditions such as 
alternative gust or maneuver descriptions for an airplane equipped with 
a load alleviation system.
    4. The following definitions are applicable to this proposed 
special condition.
    (a) Structural performance: Capability of the airplane to meet the 
structural requirements of 14 CFR part 25.
    (b) Flight limitations: Limitations that can be applied to the 
airplane flight conditions following an in-flight occurrence and that 
are included in the flight manual (e.g., speed limitations, avoidance 
of severe weather conditions, etc.).
    (c) Operational limitations: Limitations, including flight 
limitations, that can be applied to the airplane operating conditions 
before dispatch (e.g., fuel, payload and master minimum equipment list 
limitations).
    (d) Probabilistic terms: The probabilistic terms (probable, 
improbable, extremely improbable) used in this proposed special 
condition are the same as those used in Sec.  25.1309.
    (e) Failure condition: The term failure condition is the same as 
that used in Sec.  25.1309; however, this proposed special condition 
applies only to system failure conditions that affect the structural 
performance of the airplane (e.g., system failure conditions that 
induce loads, change the response of the airplane to inputs such as 
gusts or pilot actions, or lower flutter margins).

B. Effects of Systems on Structures

    1. General. The following criteria will be used in determining the 
influence of a system and its failure conditions on the airplane 
structure.
    2. System fully operative. With the system fully operative, the 
following apply:
    (a) Limit loads must be derived in all normal operating 
configurations of the system from all the limit conditions specified in 
Subpart C (or used in lieu of those specified in Subpart C), taking 
into account any special behavior of such a system or associated 
functions or any effect on the structural performance of the airplane 
that may occur up to the limit loads. In particular, any significant 
nonlinearity (rate of displacement of control surface, thresholds or 
any other system nonlinearities) must be accounted for in a realistic 
or conservative way when deriving limit loads from limit conditions.
    (b) The airplane must meet the strength requirements of part 25 
(static strength, residual strength), using the specified factors to 
derive ultimate loads from the limit loads defined above. The effect of 
nonlinearities must be investigated beyond limit conditions to ensure 
the behavior of the system presents no anomaly compared to the behavior 
below limit conditions. However, conditions beyond limit conditions 
need not be considered when it can be shown that the airplane has 
design features that will not allow it to exceed those limit 
conditions.
    (c) The airplane must meet the aeroelastic stability requirements 
of Sec.  25.629.
    3. System in the failure condition. For any system failure 
condition not shown to be extremely improbable, the following apply:
    (a) At the time of occurrence. Starting from 1-g level flight 
conditions, a realistic scenario, including pilot corrective actions, 
must be established to determine the loads occurring at the time of 
failure and immediately after the failure.
    (1) For static strength substantiation, these loads multiplied by 
an appropriate factor of safety that is related to the probability of 
occurrence of the failure are ultimate loads to be considered for 
design. The factor of safety (FS) is defined in Figure 1.

[[Page 8318]]

[GRAPHIC] [TIFF OMITTED] TP14FE11.012

    (2) For residual strength substantiation, the airplane must be able 
to withstand two thirds of the ultimate loads defined in subparagraph 
B.3(a)(1). For pressurized cabins, these loads must be combined with 
the normal operating differential pressure.
    (3) Freedom from aeroelastic instability must be shown up to the 
speeds defined in Sec.  25.629(b)(2). For failure conditions that 
result in speeds beyond VC/MC, freedom from 
aeroelastic instability must be shown to increased speeds, so that the 
margins intended by Sec.  25.629(b)(2) are maintained.
    (4) Failures of the system that result in forced structural 
vibrations (oscillatory failures) must not produce loads that could 
result in detrimental deformation of primary structure.
    (b) For the continuation of the flight. For the airplane in the 
system failed state, and considering any appropriate reconfiguration 
and flight limitations, the following apply:
    (1) The loads derived from the following conditions (or used in 
lieu of the following conditions) at speeds up to VC/
MC (or the speed limitation prescribed for the remainder of 
the flight) must be determined:
    (i) The limit symmetrical maneuvering conditions specified in Sec.  
25.331 and in Sec.  25.345.
    (ii) The limit gust and turbulence conditions specified in Sec.  
25.341 and in Sec.  25.345.
    (iii) The limit rolling conditions specified in Sec.  25.349 and 
the limit unsymmetrical conditions specified in Sec.  25.367 and Sec.  
25.427(b) and (c).
    (iv) The limit yaw maneuvering conditions specified in Sec.  
25.351.
    (v) The limit ground loading conditions specified in Sec.  25.473 
and Sec.  25.491.
    (2) For static strength substantiation, each part of the structure 
must be able to withstand the loads in paragraph B.3(b)(1) of this 
proposed special condition multiplied by a factor of safety depending 
on the probability of being in this failure state. The factor of safety 
is defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TP14FE11.013

Qj = (Tj)(Pj)

Where:

Qj = Probability of being in failure condition j
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)

    Note:  If Pj is greater than 10-3 per flight hour 
then a 1.5 factor of safety must be applied to all limit load 
conditions specified in Subpart C.

    (3) For residual strength substantiation, the airplane must be able 
to withstand two thirds of the ultimate loads defined in paragraph 
B.3(b)(2) of this proposed special condition. For pressurized cabins, 
these loads must be combined with the normal operating differential 
pressure.
    (4) If the loads induced by the failure condition have a 
significant effect on fatigue or damage tolerance then their effects 
must be taken into account.
    (5) Freedom from aeroelastic instability must be shown up to a 
speed determined from Figure 3. Flutter clearance speeds V' and V'' may 
be

[[Page 8319]]

based on the speed limitation specified for the remainder of the flight 
using the margins defined by Sec.  25.629(b).
[GRAPHIC] [TIFF OMITTED] TP14FE11.014

V' = Clearance speed as defined by Sec.  25.629(b)(2).
V'' = Clearance speed as defined by Sec.  25.629(b)(1).
Qj = (Tj)(Pj) where:
Qj = Probability of being in failure condition j
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)

    Note:  If Pj is greater than 10-3 per flight hour, 
then the flutter clearance speed must not be less than V''.

    (6) Freedom from aeroelastic instability must also be shown up to 
V' in Figure 3 above, for any probable system failure condition 
combined with any damage required or selected for investigation by 
Sec.  25.571(b).
    (c) Consideration of certain failure conditions may be required by 
other sections of 14 CFR part 25 regardless of calculated system 
reliability. Where analysis shows the probability of these failure 
conditions to be less than 10-9, criteria other than those 
specified in this paragraph may be used for structural substantiation 
to show continued safe flight and landing.
    4. Failure indications. For system failure detection and 
indication, the following apply:
    (a) The system must be checked for failure conditions, not 
extremely improbable, that degrade the structural capability below the 
level required by part 25 or significantly reduce the reliability of 
the remaining system. As far as reasonably practicable, the flight crew 
must be made aware of these failures before flight. Certain elements of 
the control system, such as mechanical and hydraulic components, may 
use special periodic inspections, and electronic components may use 
daily checks, in lieu of detection and indication systems to achieve 
the objective of this requirement. These certification maintenance 
requirements must be limited to components that are not readily 
detectable by normal detection and indication systems, and where 
service history shows that inspections will provide an adequate level 
of safety.
    (b) The existence of any failure condition, not extremely 
improbable, during flight that could significantly affect the 
structural capability of the airplane and for which the associated 
reduction in airworthiness can be minimized by suitable flight 
limitations, must be signaled to the flight crew. For example, failure 
conditions that result in a factor of safety between the airplane 
strength and the loads of Subpart C below 1.25, or flutter margins 
below V'', must be signaled to the crew during flight.
    5. Dispatch with known failure conditions. If the airplane is to be 
dispatched in a known system failure condition that affects structural 
performance, or that affects the reliability of the remaining system to 
maintain structural performance, then the provisions of this proposed 
special condition must be met, including the provisions of paragraph 
B.2 for the dispatched condition and paragraph B.3 for subsequent 
failures. Expected operational limitations may be taken into account in 
establishing Pj as the probability of failure occurrence for 
determining the safety margin in Figure 1. Flight limitations and 
expected operational limitations may be taken into account in 
establishing Qj as the combined probability of being in the dispatched 
failure condition and the subsequent failure condition for the safety 
margins in Figures 2 and 3. These limitations must be such that the 
probability of being in this combined failure state and then 
subsequently encountering limit load conditions is extremely 
improbable. No reduction in these safety margins is allowed if the 
subsequent system failure rate is greater than 1E-3 per hour.

    Issued in Renton, Washington, on February 3, 2011.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-3215 Filed 2-11-11; 8:45 am]
BILLING CODE 4910-13-P