82 FR 30800 - Special Conditions: Safran Aircraft Engines, Silvercrest-2 SC-2D; Rated Takeoff Thrust at High Ambient Temperature

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 82, Issue 126 (July 3, 2017)

This action proposes special conditions for the Safran Aircraft Engines (SAE), Silvercrest-2 SC-2D engine model. This engine will have a novel or unusual design feature associated with an additional takeoff rating that increases the exhaust gas temperature (EGT) limit to maintain takeoff thrust in certain high ambient temperature conditions for a maximum accumulated usage of 20 minutes in any one flight. 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.

[Federal Register Volume 82, Number 126 (Monday, July 3, 2017)]
[Proposed Rules]
[Pages 30800-30802]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2017-14043]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2017-0586; Notice No. 33-17-01-SC]


Special Conditions: Safran Aircraft Engines, Silvercrest-2 SC-2D; 
Rated Takeoff Thrust at High Ambient Temperature

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Safran 
Aircraft Engines (SAE), Silvercrest-2 SC-2D engine model. This engine 
will have a novel or unusual design feature associated with an 
additional takeoff rating that increases the exhaust gas temperature 
(EGT) limit to maintain takeoff thrust in certain high ambient 
temperature conditions for a maximum accumulated usage of 20 minutes in 
any one flight. 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 July 6, 2017.

ADDRESSES: Send comments identified by docket number [FAA-2017-0586] 
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 of 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 8 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 http://www.regulations.gov, as described in the 
system of records notice (DOT/ALL-14 FDMS), which can be reviewed at 
http://www.transportation.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 Room in 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: Tara Fitzgerald, ANE-112, Engine and 
Propeller Directorate, Aircraft Certification Service, 1200 District 
Avenue, Burlington, Massachusetts, 01803-5213; telephone (781) 238-
7130; facsimile (781) 238-7199; email [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    Certification of the Silvercrest-2 SC-2D engine model is currently 
scheduled for August 2018. The substance of these special conditions 
has been subject to the notice and public comment procedure. Therefore, 
because a delay would significantly affect the applicant's 
certification of the engine, we are shortening the public comment 
period to end on July 6, 2017.
    We invite interested persons to participate in this rulemaking by 
submitting 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 special 
condition, 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.

Background

    On April 19, 2011, SNECMA, now known as SAE, applied for a type 
certificate for the Silvercrest-2 SC-2D engine model. On April 30, 
2014, SAE requested an extension to their original type certificate 
application, which the FAA granted through June 30, 2015. On May 26, 
2015, SAE requested another extension to their type certificate 
application, which the FAA granted through September 30, 2018.
    SAE proposed an additional takeoff rating to maintain takeoff 
thrust in certain high ambient temperature conditions with all engines 
operating (AEO) for the Silvercrest-2 SC-2D engine model. Therefore, 
the Silvercrest-2 SC-2D engine model would have two different takeoff 
ratings. The first rating corresponds with the rated takeoff thrust of 
the engine. The second takeoff rating maintains the takeoff thrust in 
certain high ambient temperature conditions. This additional takeoff 
rating is named ``Rated Takeoff Thrust at High Ambient Temperature'' 
(Rated TOTHAT). The Rated TOTHAT is an approved engine thrust developed 
under specified altitudes and temperatures within the operating 
limitations established for the engine during takeoff operation for a 
maximum usage of 20 minutes in any one flight.

Type Certification Basis

    Under the provisions of title 14, Code of Federal Regulations (14 
CFR) 21.17, SAE must show that the Silvercrest-2 SC-2D meets the 
applicable provisions of 14 CFR part 33, as amended by Amendments 33-1 
through 33-34 in effect on the date of application.
    If the FAA finds that the applicable airworthiness regulations do 
not contain adequate or appropriate safety standards for the 
Silvercrest-2 SC-2D engine model, 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

[[Page 30801]]

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 complying with the applicable product airworthiness 
regulations and the requirements of the special conditions, the 
Silvercrest-2 SC-2D engine model 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 Silvercrest-2 SC-2D engine model will incorporate a novel or 
unusual design feature, referred to as ``Rated TOTHAT''. This 
additional takeoff rating increases the EGT limit to maintain takeoff 
thrust in certain high ambient temperature conditions for a maximum of 
20 minutes in any one flight.

Discussion

    The Rated TOTHAT is designed for use during takeoff in specified 
high altitudes and high ambient temperature conditions to maintain 
thrust during takeoff for a maximum of 20 minutes in any one flight. 
These proposed special conditions contain additional mandatory post-
flight inspection and maintenance action requirements associated with 
any use of the Rated TOTHAT. These requirements add a rating definition 
in part 1.1 and mandate mandatory inspections in the instructions for 
continued airworthiness (ICA); instructions for installing and 
operating the engine; engine rating and operating limitations; 
instrument connection; and endurance testing.
    The current requirements of the endurance test under Sec.  33.87 
represent a typical airplane flight profile and the severity of the 
takeoff rating. Therefore, the endurance test under Sec.  33.87 covers 
normal, all-engines-operating takeoff conditions for which the engine 
control system limits the engine to the takeoff thrust rating. It is 
intended to represent the airplane flight profile during takeoff under 
specified ambient temperatures for a time until the mandatory 
inspection and maintenance actions can be performed.
    These proposed special conditions require additional test cycles 
that include at least a 150 hours of engine operation as specified in 
Sec.  33.87(a), to demonstrate the engine is capable of performing the 
Rated TOTHAT rating during AEO conditions without disassembly or 
modification.
    The associated engine deterioration, after use of the Rated TOTHAT, 
is not known without the intervening mandatory inspections in these 
special conditions. These mandatory inspections ensure the engine will 
continue to comply with its certification basis, which includes these 
proposed special conditions, after any use of the Rated TOTHAT. The 
applicant is expected to assess the deterioration from use of the Rated 
TOTHAT. The airworthiness limitations section (ALS) must prescribe the 
mandatory post-flight inspections and maintenance actions associated 
with any use of the Rated TOTHAT.
    These 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, these proposed special conditions are 
applicable to the Silvercrest-2 SC-2D engine model. Should SAE 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 the Rated TOTHAT features on the 
Silvercrest-2 SC-2D engine model. It is not a rule of general 
applicability and applies only to SAE, 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, and 44704.

The Proposed Special Conditions

    Accordingly, the FAA proposes, the following special conditions as 
part of the type certification basis for SAE, Silvercrest-2 SC-2D 
engine model.

1. Part 1 Definition

    ``Rated Take-off Thrust at High Ambient Temperature'' (Rated 
TOTHAT) means the approved engine thrust developed under specified 
altitudes and temperatures within the operating limitations established 
for the engine during takeoff operation. Use is limited to two periods, 
no longer than 10 minutes each under one engine inoperative (OEI) 
conditions or 5 minutes each under AEO conditions in any one flight for 
a maximum accumulated usage of 20 minutes in any one flight. Each 
flight where the Rated TOTHAT is used must be followed by mandatory 
inspection and maintenance actions.

2. Part 33 Requirements

    In addition to the airworthiness standards in 14 CFR part 33, 
effective February 1, 1965, amendments 33-1 through 33-34 applicable to 
the engine and the Rated TOTHAT, the following special conditions 
apply:
    (a) Section 33.4, Instructions for Continued Airworthiness.
    (1) The ALS must prescribe the mandatory post-flight inspections 
and maintenance actions associated with any use of the Rated TOTHAT.
    (2) The applicant must validate the adequacy of the inspections and 
maintenance actions required under paragraph 2(a)(1) of these special 
conditions.
    (3) The applicant must establish an in-service engine evaluation 
program to ensure the continued adequacy of the instructions for 
mandatory post-flight inspections and maintenance actions prescribed 
under paragraph 2(a)(1) of these special conditions, and of the data 
for thrust assurance procedures required by paragraph 2(b)(2) of these 
special conditions. The program must include service engine tests or 
equivalent service engine test experience on engines of similar design 
and evaluations of service usage of the Rated TOTHAT.
    (b) Section 33.5, Instruction manual for installing and operating 
the engine.
    (1) Installation Instructions:
    (i) The applicant must identify the means, or provisions for means, 
provided in compliance with the requirements of paragraph 2(e) of these 
special conditions.
    (ii) The applicant must specify that the engine thrust control 
system automatically resets the thrust on the operating engine to the 
Rated TOTHAT level when one engine fails during takeoff at specified 
altitudes and temperatures.
    (iii) The applicant must specify that the Rated TOTHAT is available 
by manual crew selection at specified altitudes and temperatures in AEO 
conditions.
    (2) Operating Instructions: The applicant must provide data on 
engine performance characteristics and variability to enable the 
airplane manufacturer to establish airplane thrust assurance 
procedures.
    (c) Section 33.7, Engine ratings and operating limitations.

[[Page 30802]]

    (1) Rated TOTHAT and the associated operating limitations are 
established as follows:
    (i) The thrust is the same as the engine takeoff rated thrust with 
extended flat rating corner point.
    (ii) The rotational speed limits are the same as those associated 
with the engine takeoff rated thrust.
    (iii) The applicant must establish a gas temperature steady-state 
limit and, if necessary, a transient gas over temperature limit for 
which the duration is no longer than 30 seconds.
    (iv) The use is limited to two periods of no longer than 10 minutes 
each under OEI conditions or 5 minutes each under AEO conditions in any 
one flight, for a maximum accumulated usage of 20 minutes in any one 
flight. Each flight where the Rated TOTHAT is used must be followed by 
mandatory inspections and maintenance actions prescribed by paragraph 
2(a)(1) of these special conditions.
    (2) The applicant must propose language to include in the type 
certificate data sheet specified in Sec.  21.41 for the following:
    (i) Rated TOTHAT and associated limitations.
    (ii) As required by Sec.  33.5(b), Operating instructions, include 
a note stating that ``Rated Takeoff Thrust at High Ambient Temperature 
(Rated TOTHAT) means the approved engine thrust developed under 
specified altitudes and temperatures within the operating limitations 
established for the engine. Use is limited to two periods, no longer 
than 10 minutes each under OEI conditions or 5 minutes each under AEO 
conditions in any one flight, for a maximum accumulated usage of 20 
minutes in any one flight. Each flight where the Rated TOTHAT is used 
must be followed by mandatory inspection and maintenance actions.''
    (iii) As required by Sec.  33.5(b), Operating instructions, include 
a note stating that the engine thrust control system automatically 
resets the thrust on the operating engine to the Rated TOTHAT level 
when one engine fails during takeoff at specified altitudes and 
temperatures, and the Rated TOTHAT is available by manual selection 
when all engines are operational during takeoff at specified altitudes 
and temperatures.
    (d) Section 33.28, Engine Control Systems.
    The engine must incorporate a means, or a provision for a means, 
for automatic availability and automatic control of the Rated TOTHAT 
under OEI conditions and must permit manual activation of the Rated 
TOTHAT under AEO conditions.
    (e) Section 33.29, Instrument connection.
    The engine must:
    (1) Have means, or provisions for means, to alert the pilot when 
the Rated TOTHAT is in use, when the event begins and when the time 
interval expires.
    (2) Have means, or provision for means, which cannot be reset in 
flight, to:
    (i) Automatically record each use and duration of the Rated TOTHAT, 
and
    (ii) Alert maintenance personnel that the engine has been operated 
at the Rated TOTHAT and permit retrieval of recorded data.
    (3) Have means, or provision for means, to enable routine 
verification of the proper operation of the means in paragraph 2(e)(1) 
and (e)(2) of these special conditions.
    (f) Section 33.85(b), Calibration tests.
    The applicant must base the calibration test on the thrust check at 
the end of the endurance test required by Sec.  33.87 of these special 
conditions.
    (g) Section 33.87, Endurance test.
    (1) In addition to the applicable requirements of Sec.  33.87(a):
    (i) The Sec.  33.87 endurance test must be modified as follows:
    (A) Modify the thirty minute test cycle at the rated takeoff thrust 
in Sec.  33.87(b)(2)(ii) to run one minute at rated takeoff thrust, 
followed by five minutes at the Rated TOTHAT, followed by the rated 
takeoff thrust for the remaining twenty-four minutes.
    (B) The modified thirty minute period described above in paragraph 
2(g)(1)(i)(A) must be repeated ten times in cycles 16 through 25 of the 
Sec.  33.87 endurance test.
    (2) After completion of the tests required by Sec.  33.87(b), as 
modified in paragraph 2(g)(1)(i) above, and without intervening 
disassembly, except as needed to replace those parts described as 
consumables in the ICA, the applicant must conduct the following test 
sequence for a total time of not less than 120 minutes:
    (i) Ten minutes at Rated TOTHAT.
    (ii) Eighty-eight minutes at rated maximum continuous thrust.
    (iii) One minute at 50 percent of rated takeoff thrust.
    (iv) Ten minutes at Rated TOTHAT.
    (v) Ten minutes at rated maximum continuous thrust.
    (vi) One minute at flight idle.
    (3) The test sequence of Sec.  33.87(b)(1) through (6) of these 
special conditions must be run continuously. If a stop occurs during 
these tests, the interrupted sequence must be repeated unless the 
applicant shows that the severity of the test would not be reduced if 
the current tests were continued.
    (4) Where the engine characteristics are such that acceleration to 
the Rated TOTHAT results in a transient over temperature in excess of 
the steady-state temperature limit identified in paragraph 2(c)(1)(iii) 
of these special conditions, the transient gas overtemperature must be 
applied to each acceleration to the Rated TOTHAT of the test sequence 
in paragraph 2(g)(2) of these special conditions.
    (h) Section 33.93, Teardown inspection.
    The applicant must perform the teardown inspection required by 
Sec.  33.93(a), after completing the endurance test prescribed by Sec.  
33.87 of these special conditions.
    (i) Section 33.201, Design and test requirements for Early ETOPS 
eligibility.
    In addition to the requirements of Sec.  33.201(c)(1), the 
simulated ETOPS mission cyclic endurance test must include two cycles 
of 10 minute duration, each at the Rated TOTHAT; one before the last 
diversion cycle and one at the end of the ETOPS test.

    Issued in Burlington, Massachusetts, on June 13, 2017.
Carlos A. Pestana,
Acting Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2017-14043 Filed 6-29-17; 4:15 pm]
BILLING CODE 4910-13-P