82 FR 43827 - 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 181 (September 20, 2017)

These special conditions are issued for the Safran Aircraft Engines (SAE), Silvercrest-2 SC-2D engine model. This engine model will have a novel or unusual design feature associated with an additional takeoff rating that maintains 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 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 181 (Wednesday, September 20, 2017)]
[Rules and Regulations]
[Pages 43827-43829]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2017-19952]



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Rules and Regulations
                                                Federal Register
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Federal Register / Vol. 82, No. 181 / Wednesday, September 20, 2017 / 
Rules and Regulations

[[Page 43827]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2017-0586; Special Conditions No. 33-019-SC]


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Safran Aircraft 
Engines (SAE), Silvercrest-2 SC-2D engine model. This engine model will 
have a novel or unusual design feature associated with an additional 
takeoff rating that maintains 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 
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: Effective September 20, 2017.

FOR FURTHER INFORMATION CONTACT: Tara Fitzgerald, AIR-6A1, Engine and 
Propeller Standards Branch, Aircraft Certification Service, 1200 
District Avenue, Burlington, Massachusetts 01803-5213; telephone (781) 
238-7130; facsimile (781) 238-7199; email [email protected].

SUPPLEMENTARY INFORMATION: Under standard practice, the effective date 
of final special conditions would be 30 days after the date of 
publication in the Federal Register. However, as the certification date 
for the SAE, Silvercrest-2 SC-2D engine model is imminent; the FAA 
finds that good cause exists to make these special conditions effective 
upon publication.

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 that maintains 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 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 engine model 
meets the applicable provisions of 14 CFR part 33, amendments 33-1 
through 33-34 in effect on the date of application. The FAA has 
determined that the applicable airworthiness regulations in part 33 do 
not contain adequate or appropriate safety standards for the 
Silvercrest-2 SC-2D engine model because of their novel and unusual 
design feature referred to as ``Rated TOTHAT''. Therefore, these 
special conditions are prescribed under the provisions of 14 CFR 11.19 
and 14 CFR 21.16, and will become part of the type certification basis 
for Silvercrest-2 SC-2D engine models in accordance with Sec.  
21.17(a)(2).
    If the Administrator finds that the applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
the SAE, 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 engine model for 
which they are issued. Should the type certificate for that engine 
model be amended later to include any other engine model(s) that 
incorporates the same novel or unusual design feature, 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 Silvercrest-2 SC-2D engine 
model must comply with the fuel venting and exhaust emission 
requirements of 14 CFR part 34.

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 exhaust gas temperature (EGT) 
limit that maintains 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. It 
maintains thrust during takeoff for a maximum of 20 minutes in any one 
flight. These 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 paragraph 1.1 below and mandate required 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 14 CFR 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, AEO takeoff conditions for which the engine control system 
limits the engine to the takeoff thrust rating. It is intended to 
represent

[[Page 43828]]

the airplane flight profile during takeoff under specified ambient 
temperatures for a time until the mandatory inspection and maintenance 
actions can be performed.
    These 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 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.

Discussion of Comments

    Notice of proposed special conditions No. 33-17-01-SC for the SAE, 
Silvercrest-2 SC-2D; Rated Takeoff Thrust at High Ambient Temperature 
engine model was published in the Federal Register on July 03, 2017 (82 
FR 30800). No comments were received, and the special conditions are 
adopted as proposed.

Applicability

    As discussed above, these 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 on the same 
type certificate incorporating the same novel or unusual design 
feature, these special conditions would apply to that model as well.

Conclusion

    This action affects only the ``Rated TOTHAT'' features on 
Silvercrest-2 SC-2D engine models. 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, 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 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 all engines operating (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, which are 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.
    (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 14 CFR 21.41 for the following:
    (i) ``Rated TOTHAT'' and associated limitations.
    (ii) As required by 14 CFR 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

[[Page 43829]]

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 30 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 30 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. Sec.  33.87(b)(1) through (b)(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 over 
temperature 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 August 23, 2017.
Karen M. Grant
Acting Manager, Engine and Propeller Standards Branch, Aircraft 
Certification Service.
[FR Doc. 2017-19952 Filed 9-19-17; 8:45 am]
 BILLING CODE 4910-13-P