80 FR 55228 - Special Conditions: Gulfstream Aerospace Corporation Model GVII-G500 Airplanes; Limit Engine Torque Loads

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 80, Issue 178 (September 15, 2015)

These special conditions are issued for the Gulfstream Model GVII-G500 airplane. These airplanes have a novel or unusual design feature as compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. This design feature includes engine size and the potential torque loads imposed by sudden engine stoppage. 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.

[Federal Register Volume 80, Number 178 (Tuesday, September 15, 2015)]
[Rules and Regulations]
[Pages 55228-55229]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2015-23100]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-1483; Special Conditions No. 25-598-SC]


Special Conditions: Gulfstream Aerospace Corporation Model GVII-
G500 Airplanes; Limit Engine Torque Loads

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Gulfstream Model 
GVII-G500 airplane. These airplanes have a novel or unusual design 
feature as compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. This design 
feature includes engine size and the potential torque loads imposed by 
sudden engine stoppage. 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: The effective date of these special conditions is September 15, 
2015. We must receive your comments by October 30, 2015.

ADDRESSES: Send comments identified by docket number FAA-2015-1483 
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: The FAA has determined that notice of, and 
opportunity for, prior public comment on these special conditions are 
impracticable because these procedures would significantly delay 
issuance of the design approval and thus delivery of the affected 
airplane.
    In addition, the substance of these special conditions has been 
subject to the public-comment process in several prior instances with 
no substantive comments received. The FAA therefore finds that good 
cause exists for making these special conditions effective upon 
issuance.

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 on or before 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 GVII airplane is a large-cabin business jet with seating for 19 
passengers. It incorporates a low, swept-wing design with winglets and 
a T-tail. The Model GVII-G500 airplane is powered by 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 controlled by active 
control/coupled side sticks.
    The Model GVII-G500 airplane wingspan is approximately 87 ft with a 
length of just over 91 ft. Maximum takeoff weight will be approximately 
76,850 lbs and maximum takeoff thrust will be approximately 15,135 lbs. 
Maximum range will be approximately 5,000 nm and maximum operating 
altitude will be 51,000 ft.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Gulfstream Aerospace Corporation must show that the Model 
GVII-500 airplane meets the applicable provisions of part 25, as 
amended by Amendments 25-1 through 25-137 thereto.
    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 Model GVII-G500 airplane 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 or similar 
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.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of

[[Page 55229]]

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: Large-bypass engines capable of larger and 
more complex dynamic loads than were envisioned when the 14 CFR 
25.361(b) rule was developed in 1957, thereby requiring issuance of 
special conditions to establish appropriate design standards for the 
Model GVII-G500 airplane.

Discussion

    The limit engine torque load imposed by sudden engine stoppage due 
to malfunction or structural failure (such as a compressor jamming) has 
been a specific requirement for transport-category airplanes since 
1957. In the past, the design torque loads associated with typical 
failure scenarios have been estimated by the engine manufacturer and 
were provided to the airframe manufacturer as limit loads. These limit 
loads were considered simple, pure-torque static loads.
    It is evident from service history that the engine-failure events 
that tend to cause the most severe loads are fan-blade failures, and 
these events occur much less frequently than the typical ``limit'' load 
condition.
    To maintain the level of safety envisioned by Sec.  25.361(b), more 
comprehensive criteria are required for the new generation of high-
bypass engines. These special conditions distinguish between the more 
common engine-failure events and those rare events resulting from 
structural failures. The more-common events are regarded as static 
torque limit load conditions. The more-severe events resulting from 
extreme engine-failure conditions (such as loss of a full fan blade at 
redline speed) are regarded as full dynamic load conditions. These are 
considered ultimate loads, and include all transient loads associated 
with the event. An additional safety factor is applied to the more-
critical airframe supporting structure.

Applicability

    As discussed above, these special conditions are applicable to the 
Model GVII-G500 airplane. Should Gulfstream Aerospace 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 series 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 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 the Gulfstream Aerospace Corporation 
Model GVII-G500 airplane.
    In lieu of Sec.  25.361(b) the following special conditions apply:
    1. For turbine engine installations, the engine mounts, pylons, and 
adjacent supporting airframe structure must be designed to withstand 1g 
level flight loads acting simultaneously with the maximum limit torque 
loads imposed by each of the following:
    a. Sudden engine deceleration due to a malfunction that could 
result in a temporary loss of power or thrust, and
    b. The maximum acceleration of the engine.
    2. For auxiliary power unit (APU) installations, the power unit 
mounts and adjacent supporting airframe structure must be designed to 
withstand 1g level-flight loads acting simultaneously with the maximum 
limit torque loads imposed by each of the following:
    a. Sudden APU deceleration due to malfunction or structural 
failure; and
    b. The maximum acceleration of the APU.
    3. For engine supporting structure, an ultimate loading condition 
must be considered that combines 1g flight loads with the transient 
dynamic loads resulting from:
    a. The loss of any fan, compressor, or turbine blade; and 
separately,
    b. Where applicable to a specific engine design, any other engine 
structural failure that results in higher loads.
    4. The ultimate loads developed from the conditions specified in 
special conditions 3(a) and 3(b), above, are to be multiplied by a 
factor of 1.0 when applied to engine mounts and pylons, and multiplied 
by a factor of 1.25 when applied to adjacent supporting airframe 
structure.
    5. Any permanent deformation that results from the conditions 
specified in special condition 3, above, must not prevent continued 
safe flight and landing.

    Issued in Renton, Washington, on September 1, 2015.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-23100 Filed 9-14-15; 8:45 am]
 BILLING CODE 4910-13-P