[Federal Register Volume 82, Number 121 (Monday, June 26, 2017)]
[Proposed Rules]
[Pages 28790-28793]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-13210]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2017-0537; Notice No. 33-17-02-SC]


Special Conditions: General Electric Company, GE9X Engine Models; 
Endurance Test Special Conditions

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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[[Page 28791]]

SUMMARY: This action proposes special conditions for the General 
Electric turbofan engine models GE9X-105B1A, -105B1A1, -105B1A2, -
105B1A3, -102B1A, -102B1A1, -102B1A2, -102B1A3, and -93B1A. These 
engine models will be referred to as ``GE9X'' in these special 
conditions. The engines will have a novel or unusual design features 
associated with the engine design. 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 August 10, 2017.

ADDRESSES: Send comments identified by docket number FAA-2017-0537 
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: 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: Dorina Mihail, ANE-111, Engine and 
Propeller Directorate, Aircraft Certification Service, 1200 District 
Avenue, Burlington, Massachusetts, 01803-5213; telephone (781) 238-
7153; facsimile (781) 238-7199; email [email protected].

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite interested people to participate in this rulemaking by 
sending written comments, data, or views. The agency also invites 
comments relating to the economic, environmental, energy, or federalism 
impacts that might result from adopting the proposals in this document. 
The most helpful comments reference a specific portion of the proposed 
special conditions, explain the reason for any recommended change, and 
include supporting data. To ensure the docket does not contain 
duplicate comments, commenters should send only one copy of written 
comments, or if comments are filed electronically, commenters should 
submit only one time.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning this proposed rulemaking. Before acting on this proposal, we 
will consider all comments we receive on or before the closing date for 
comments. We will consider comments filed after the comment period has 
closed if it is possible to do so without incurring expense or delay. 
We may change these special conditions based on the comments we 
receive.
    Proprietary or Confidential Business Information: Commenters should 
not file proprietary or confidential business information in the 
docket. Such information must be sent or delivered directly to the 
person identified in the FOR FURTHER INFORMATION CONTACT section of 
this document, and marked as proprietary or confidential. If submitting 
information on a disk or CD-ROM, mark the outside of the disk or CD-
ROM, and identify electronically within the disk or CD-ROM the specific 
information that is proprietary or confidential.
    Under 14 CFR 11.35(b), if the FAA is aware of proprietary 
information filed with a comment, the agency does not place it in the 
docket. It is held in a separate file to which the public does not have 
access, and the FAA places a note in the docket that it has received 
it. If the FAA receives a request to examine or copy this information, 
it treats it as any other request under the Freedom of Information Act 
(5 U.S.C. 552). The FAA processes such a request under Department of 
Transportation procedures found in 49 CFR part 7.

Background

    On January 29, 2016, General Electric Company (GE) applied for type 
certificate application for GE's GE9X turbofan engine models. The GE9X 
engine models are high-bypass-ratio engines that incorporate novel and 
unusual design features. The GE9X engine models incorporate new 
technologies such that it cannot run the endurance test conditions 
prescribed in Sec.  33.87 without significant test-enabling 
modifications, making the test vehicle non-representative of the 
proposed type design. An alternative endurance test cycle has been 
developed that provides a level of safety equivalent with that intended 
by Sec.  33.87. The proposed alternate endurance test provides the test 
conditions that allow the engine to be run in type design configuration 
and demonstrate engine operability and durability as well as systems 
functionality to a level intended by the current Sec.  33.87 rule.

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, as amended by Amendments 33-1 through 
33-34.
    If the FAA finds that the applicable airworthiness regulations do 
not contain adequate or appropriate safety standards for the GE9X 
engine models 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 engine model 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 or similar 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: Technological advances that reduce noise and 
emissions while improving fuel

[[Page 28792]]

efficiency and increasing thrust, when compared to previous similar 
certificated GE engine models.
    The GE9X series engine type design incorporates new technologies 
such that it cannot run the endurance test conditions prescribed in 
Sec.  33.87 without significant test-enabling modifications, making the 
test vehicle non-representative of the proposed type design. The 
modifications needed to run the Sec.  33.87 endurance test have become 
increasingly complex over time, and reconciling the test results to the 
proposed type design has also become increasingly difficult.
    For past certifications, GE has shown that the proposed engine 
design, as modified, still represented the durability and operating 
characteristics of the intended type design but the modifications 
needed to the GE9X engine model to run the Sec.  33.87 endurance test 
cannot be reconciled and would affect the test outcome.

Discussion

    These proposed special conditions provide the necessary conditions 
for verification of engine-level and component-level effects as 
intended by the current Sec.  33.87 endurance test. The special 
conditions include a demonstration for the oil, fuel, air bleed, and 
accessory drive systems as required in the current Sec.  33.87 
endurance test.
    The level of severity is provided by an engine test demonstration 
at the gas path limiting temperature and at shaft speed redlines and at 
the most extreme shaft speeds as determined through a critical point 
analysis (CPA). In addition, times on condition and cycle counts were 
developed to allow additional challenges to the new and novel features 
that would not have been as challenged by the current Sec.  33.87 test 
schedule. The alternate test demonstrates no potential safety issue 
will develop while operating in service.
    The proposed cycles dwell time duration reflect that GE9X does not 
have a 10-minute OEI extension for the takeoff rating.
    The special conditions for Sec.  33.4 and Sec.  33.29 are added to 
support an equivalent compliance by means of mandatory inspections 
prescribed in paragraph (b)(3) of the Sec.  33.87 special conditions.
    These special condition requirements maintain a level of safety 
equivalent to the level intended by the applicable airworthiness 
standards in effect on the date of application.

Applicability

    As discussed above, the proposed special conditions are applicable 
to the GE9X engine model(s). 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 
feature, the special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on the GE9X turbofan 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 Proposed Special Conditions

0
Accordingly, the FAA proposes the following special conditions as part 
of the type certification basis for the GE9X engine models: GE9X-
105B1A, -105B1A1, -105B1A2, -105B1A3, -102B1A, -102B1A1, -102B1A2, -
102B1A3, and -93B1A.

PART 33--REQUIREMENTS


Sec.  33.4   Instructions for Continued Airworthiness.

    (a) The Airworthiness Limitations section must prescribe the 
mandatory post-flight inspections and maintenance actions associated 
with any exceedance required by Sec.  33.87, paragraph (b)(3), of these 
special conditions.


Sec.  33.29   Instrument connection.

    (a) The engine must have means, or provisions for means, to 
automatically record and alert maintenance personnel for each 
occurrence of any exceedance required by Sec.  33.87 paragraph (b)(3), 
of these special conditions.


Sec.  33.87  Endurance Test.

    (a) General: The applicant must show that the endurance test 
schedule in combination with any prescribed mandatory actions provide 
an equivalent level of severity and demonstration of durability and 
operability as that intended by Sec.  33.87(a) and (b) for a turbofan 
engine. When showing that the level of durability is equivalent with 
that intended by the rule, the applicant must consider the damage 
accumulated during the test for the limiting damage mechanisms for 
components and engine systems, up to and including the applicable 
limitations declared in the Type Certificate Data Sheets (TCDS). The 
test cycle content must create conditions in the engine for a 
sufficient amount of time to demonstrate no potential safety issue will 
develop from the limiting damage mechanisms while operating in service. 
The following minimum requirements apply:
    (1) The tests in paragraphs (b), (c), and (d) of these special 
conditions, for total cumulative and dwell time duration between ground 
idle and the takeoff thrust prescribed in these special conditions. The 
test cycle durations must include all maximums allowed in the TCDS and 
expected service operation.
    (2) Requirements of Sec.  33.87(a)(1), (2), (4), and (6) applicable 
to turbofan engines.
    (3) Requirements of Sec.  33.87(a)(3) applicable to the temperature 
of external surfaces of the engine, if limited.
    (4) Testing for maximum air bleed must be at least equal with the 
prescribed test required in Sec.  33.87(a)(5). However, for these 
cycles, the thrust or the rotor shaft rotational speed may be less than 
100 percent of the value associated with the particular operation being 
tested if the FAA finds that the validity of the endurance test is not 
compromised.
    (5) Testing for engine fuel, oil, and hydraulic fluid pressure and 
oil temperature must be at least equal with the prescribed test 
required in Sec.  33.87(a)(7).
    (6) If the number of occurrences of either transient rotor shaft 
overspeed or transient gas over temperature is not limited, at least 
155 accelerations must be made at the limiting overspeed or over 
temperature. If the number of occurrences is limited, that number of 
accelerations must be made at the limiting overspeed or over 
temperature.
    (7) One hundred starts must be made, of which 25 starts must be 
preceded by at least a two-hour engine shutdown. There must be at least 
10 false engine starts, pausing for the applicant's specified minimum 
fuel drainage time, before attempting a normal start. There must be at 
least 10 normal restarts with not longer than 15 minutes since engine 
shutdown. The remaining starts may be made after completing the 
endurance testing prescribed by these special conditions.
    (8) Unless otherwise specified (i.e. (d)(2)), for accelerations 
from ground idle to takeoff, the throttle must be moved in not more 
than one second, except that, if different regimes of control 
operations are incorporated necessitating scheduling of the thrust-
control lever motion in going from one

[[Page 28793]]

extreme position to the other, a longer period of time is acceptable, 
but not more than two seconds.
    (i) When operating with max oil temperatures the throttle movement 
may be `stair-stepped' to allow for oil temperature stabilization for 
durations greater than two seconds.
    (9) The applicant must validate any analytical methods used for 
compliance with these special conditions. Validation includes the 
ability to accurately predict an outcome applicable to the engine being 
tested.
    (10) The applicant must perform the endurance test on an engine 
that substantially conforms to its type design. Modifications may be 
made as needed to achieve test conditions and/or engine operating 
conditions representative of the type design.
    (b) Conduct the endurance test at or above the declared shaft 
speeds and gas temperatures limits, and at or above conditions 
representative of critical points (speeds, temperatures, rated thrust) 
in the operating envelope.
    (1) Conduct the endurance test at or above the rated takeoff thrust 
and rated maximum continuous thrust and with the associated limits for 
rotor speeds and gas temperature (redlines), as follows:
    (i) Either rotor speed or gas temperature, or concurrent rotor 
speed and gas temperature if analysis indicates a combination of 
redline operational conditions is possible to occur in service, must be 
at least 100 percent of the values associated with the engine rating 
being tested.
    (ii) The cumulative test time duration and number of cycles must be 
representative of the rotor speed and gas temperature excursions to 
redlines that can be expected to occur in between overhauls.
    (iii) The time durations for each takeoff or maximum continuous 
segment must include all maximums allowed in the TCDS and expected 
service operation and must include the following cycles:
    (A) At least one (1) takeoff cycle of 5 minutes time duration at 
the low pressure rotor speed limit and gas temperature limit 
(redlines).
    (B) At least one (1) takeoff cycle of 5 minutes time duration at 
the high pressure rotor speed limit and gas temperature limit 
(redlines).
    (C) In lieu of the separate cycles specified in paragraphs (A) and 
(B) of this section, the applicant may run the low pressure and high 
pressure rotor speeds and gas temperature limits (redlines) in the same 
cycle. However in this case, the applicant must run at least 2 cycles 
of 5 minutes time duration each.
    (2) Conduct the endurance test at or above the rated takeoff thrust 
and the rated maximum continuous thrust with rotor speeds at or above 
those determined by a critical point analysis (CPA) and with gas 
temperature redline conditions as follows:
    (i) The applicant must determine through a CPA the highest rotor 
shaft rotational speeds (CPA speeds) expected to occur for each rotor 
shaft system within the declared operating envelope. The CPA must be 
conducted for the takeoff and maximum continuous rated thrust and must 
consider the declared operating envelope, engine deterioration, engine-
to-engine variability, and any other applicable variables that can 
cause the engine to operate at the extremes of its performance ratings.
    (ii) Except as provided in paragraph (b)(3)(ii) of these special 
conditions, conduct a cyclic test between ground idle and combined 
takeoff and maximum continuous thrust ratings, as follows:
    (A) Eighteen hours and forty five minutes (18.75 hours) cumulated 
time duration at or above the rated takeoff thrust, the gas temperature 
limit for takeoff (redline), and the CPA rotor speeds for takeoff 
determined per paragraph (b)(2)(i) of these special conditions.
    (B) Forty five (45) hours cumulated time duration at or above the 
rated maximum continuous thrust, the gas temperature limit for maximum 
continuous (redline), and the CPA rotor speeds for maximum continuous 
determined per paragraph (b)(2)(i) of these special conditions.
    (C) The time durations for each takeoff or maximum continuous 
segments must include all maximums allowed in the TCDS and expected 
service operation, and must include at least one maximum continuous 
cycle of 30 minutes run continuously.
    (3) If the cyclic shaft speed excursions specified in paragraphs 
(b)(1) or (b)(2) of these special conditions cannot be demonstrated in 
the test, then an alternative equivalent with the rule intent must be 
provided. Alternatives may include alternate means of test 
demonstration, mandatory actions, or other means found acceptable to 
the FAA. The applicant must prescribe a mandatory action plan for 
engine operation between the shaft speeds demonstrated for a minimum of 
cumulated 18.75 hours at or above rated takeoff and 45 hours at or 
above rated maximum continuous, respectively, and the declared speed 
limits (redlines), as follows:
    (i) Prescribe post-event actions or operating limitations 
acceptable to the FAA for operation below the declared speed limits 
(redlines) and above the CPA speeds.
    (ii) If the test required by (b)(2)(ii) of these special conditions 
can only be accomplished at a rotor shaft speed lower than the CPA 
speed, prescribe post-event actions or operating limitations acceptable 
to the FAA for operation below that CPA speed and above the value 
demonstrated during the test.
    (c) Conduct the endurance test at the incremental cruise thrust 
that must be at least equal with the prescribed test required in Sec.  
33.87(b)(4). The 25 incremental test cycles must be uniformly 
distributed throughout the entire endurance test.
    (d) Conduct at least 300 cycles between ground idle and combined 
takeoff and maximum continuous thrust, as follows:
    (1) Each cycle to include acceleration to or above rated takeoff 
thrust, deceleration from takeoff to ground idle, followed by 5 to 15 
seconds at ground idle, acceleration to or above rated maximum 
continuous thrust, and deceleration to ground idle.
    (2) The throttle movement from ground idle to rated takeoff or 
maximum continuous thrust and from rated takeoff thrust to ground idle 
should be not more than one (1) second, except that, if different 
regimes of control operations are incorporated necessitating scheduling 
of the thrust-control lever motion in going from one extreme position 
to the other, a longer period of time is acceptable, but not more than 
two seconds. The throttle move from rated maximum continuous thrust to 
ground idle should not be more than five (5) seconds.
    (3) The time durations for each cycle associated with either 
takeoff or maximum continuous thrust segments must include all maximums 
allowed in the TCDS and expected service operation, and must include 
the following cycles:
    (i) Three (3) cycles of 5 minutes each and one (1) cycle of 10 
minutes at the takeoff thrust.
    (ii) Three (3) cycles of 30 minutes each at the maximum continuous 
thrust.

    Issued in Burlington, Massachusetts, on June 1, 2017.
Carlos A. Pestana,
Acting Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2017-13210 Filed 6-23-17; 8:45 am]
 BILLING CODE 4910-13-P