[Federal Register Volume 82, Number 60 (Thursday, March 30, 2017)]
[Rules and Regulations]
[Pages 15611-15612]
[FR Doc No: 2017-06277]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2017-0171; Special Conditions No. 33-018-SC

Special Conditions: General Electric Company, GE9X Engine Models;
Incorporation of Composite Fan Blades

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 General Electric
(GE) GE9X turbofan engine models. These engine models will have novel
or unusual design features associated with composite fan blades. 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: The effective date of these special conditions is April 14,
2017. We must receive your comments by May 1, 2017.

ADDRESSES: Send comments identified by docket number FAA-2017-0171
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<PHONE_NUMBER>.
    Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments
from the public to better inform its rulemaking process. DOT posts
these comments, without edit, including any personal information the
commenter provides, to www.regulations.gov, as described in the system
of records notice (DOT/ALL-14 FDMS), which can be reviewed at
www.dot.gov/privacy.
    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 the 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: For technical questions concerning
these special conditions, contact Jay Turnberg, Engine and Propeller
Directorate, Aircraft Certification Service, 1200 District Avenue,
Burlington, Massachusetts, 01803-5213; telephone<PHONE_NUMBER>;
facsimile<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and
opportunity for prior public comment on, these special conditions is
impracticable because these procedures would significantly delay
issuance of the Type Certificate approval and thus, delivery of the
affected engines.
    In addition, the substance of these special conditions has been
subjected to the notice and comment period in several prior instances,
and has been derived without substantive change from those previously
issued. It is unlikely that prior public comment would result in a
significant change from the substance contained herein. Therefore,
because a delay would significantly affect the certification of the
engine, which is imminent, the FAA has determined that prior public
notice and comment are unnecessary and impracticable, and good cause
exists for adopting these special conditions.

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 January 29, 2016, GE applied for a type certificate for their
new GE9X turbofan engine models. The High-Bypass-Ratio GE9X engine
models incorporate composite fan blades, a novel or unusual design
feature. These fan blades have significant material property
characteristics differences from conventional, single load path,
metallic fan blades. Additionally, they have multiple load path
features and/or crack arresting feature capabilities that, during the
blade life, may prevent delamination, crack propagation, and/or blade
failure.
    Because of their novel or unusual design, these fan blades require
additional airworthiness standards for GE9X engine type certification,
to account for material property and failure mode differences with
conventional fan blades. The applicable airworthiness regulations that
exist do not contain appropriate safety standards for these new blades.
The FAA may allow for application of different fan blade containment
requirements, if GE demonstrates improved load path features and/or
crack arresting feature capabilities of the new blade design, below the
inner annulus flow path line.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, GE must show that the GE9X engine models meet the
applicable provisions of part 33, ``Airworthiness Standards, Aircraft
Engines,'' dated February 1, 1965, as amended by Amendments 33-1
through 33-34, dated January 5, 2015. The FAA has determined that the
applicable airworthiness regulations in part 33 do not contain adequate
or appropriate safety standards for the GE9X engine models because of
their novel and unusual fan blade design features. Therefore, these
special conditions are prescribed under the provisions of 14 CFR 11.19
and 21.16, and will become part of the type certification basis for
GE9X engine models in accordance with Sec.  21.17(a)(2).
    Special conditions are initially applicable to the engine models
for which they are issued. Should the type certificate for that engine
model be amended later to include any other engine models that
incorporate the same novel or unusual design features, the special
conditions would also apply to the other engine models under Sec.
21.101.
    In addition to complying with the applicable product airworthiness
regulations and special conditions, the GE9X engine models must comply
with the fuel venting and exhaust emission requirements of 14 CFR part
34.
    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 GE9X engine models will incorporate the following novel or

unusual design features: Composite fan blades. These fan blades will
have significant differences in material property characteristics as
compared to conventionally designed fan blades using non-composite
metallic materials. Composite material designs can incorporate multiple
load paths and/or crack arresting features that prevent delamination or
crack propagation that could result in blade failure during the blade
service life. These blades require additional airworthiness standards
for type certification of the GE9X engine models.

Discussion

    As discussed in the summary section, the GE9X engine models
incorporate composite fan blades instead of conventional, single load
path, metallic fan blades, which is a novel or unusual design feature
for aircraft engines. The applicable airworthiness regulations do not
contain adequate or appropriate safety standards for this design
feature.

Applicability

    As discussed above, these special conditions are applicable to the
GE9X engine models. Should GE apply at a later date for a change to the
type certificate to include another model on the same type certificate
incorporating the same novel or unusual design features, the special
conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features
on GE9X engine models. It is not a rule of general applicability and
applies only to GE, who requested FAA approval of this engine feature.

List of Subjects in 14 CFR Part 33

    Aircraft, Engines, 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 GE9X engine models.
    1. Special Conditions: General Electric Company, GE9X Engine
Models; Incorporation of Composite Fan Blades. In lieu of the fan blade
containment test with the fan blade failing at the outermost retention
groove as specified in Sec.  33.94(a)(1), complete the following
requirements:
    (a) Conduct an engine fan blade containment test with the fan blade
failing at the inner annulus flow path line instead of at the outermost
retention groove.
    (b) Substantiate by test and analysis, or other methods acceptable
to the FAA, that a fan disk and fan blade retention system with minimum
material properties can withstand, without failure, a centrifugal load
equal to two times the maximum load the retention system could
experience within approved engine operating limitations. The fan blade
retention system includes the portion of the fan blade from the inner
annulus flow path line inward to the blade dovetail, the blade
retention components, and the fan disk and fan blade attachment
features.
    (c) Using a procedure approved by the FAA, establish an operating
limitation that specifies the maximum allowable number of start-stop
stress cycles for the fan blade retention system. The life evaluation
must include the combined effects of high-cycle and low-cycle fatigue.
If the operating limitation is less than 100,000 cycles, that
limitation must be specified in Chapter 5 of the Engine Manual
Airworthiness Limitation Section. The procedure used to establish the
maximum allowable number of start-stop stress cycles for the fan blade
retention system will incorporate the integrity requirements specified
in paragraphs (c)(1), (c)(2), and (c)(3) of these special conditions
for the fan blade retention system.
    (1) An engineering plan which establishes and maintains that the
combinations of loads, material properties, environmental influences,
and operating conditions, including the effects of parts influencing
these parameters, are well known or predictable through validated
analysis, test, or service experience.
    (2) A manufacturing plan that identifies the specific manufacturing
constraints necessary to consistently produce the fan blade retention
system with the attributes required by the engineering plan.
    (3) A service management plan that defines in-service processes for
maintenance and repair of the fan blade retention system, which will
maintain attributes consistent with those required by the engineering
plan.
    (d) Substantiate by test and analysis, or other methods acceptable
to the FAA, that the blade design below the inner annulus flow path
line provides multiple load paths and/or crack arresting features that
prevent delamination or crack propagation to blade failure during the
life of the blade.
    (e) Substantiate that, during the service life of the engine, the
total probability of the occurrence of a hazardous engine effect
defined in Sec.  33.75 due to an individual blade retention system
failure resulting from all possible causes will be extremely
improbable, with (a cumulative calculated probability of failure of
less than 10-9) per engine flight hour.
    (f) Substantiate by test or analysis that not only will the engine
continue to meet the requirements of Sec.  33.75 following a lightning
strike on the composite fan blade structure, but that the lightning
strike will not cause damage to the fan blades that would prevent
continued safe operation of the affected engine.
    (g) Account for the effects of in-service deterioration,
manufacturing variations, minimum material properties, and
environmental effects during the tests and analyses required by
paragraphs (b), (c), (d), (e), and (f) of these special conditions.
    (h) Propose fleet leader monitoring and field sampling programs
that will monitor the effects of engine fan blade usage on fan blade
retention system integrity. The programs must be approved by the FAA
prior to certification of the GE9X engine models.
    (i) Mark each fan blade legibly and permanently with a part number
and a serial number.

    Issued in Burlington, Massachusetts, on March 23, 2017.
Robert J. Ganley,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 2017-06277 Filed 3-29-17; 8:45 am]
BILLING CODE 4910-13-P