Document ID: FAA-2012-0745-0001
Agency: faa
Document Type: Proposed Rule
Title: Special Conditions: General Electric CT7-2E1 Turboshaft Engine
Posted Date: 2012-07-20T04:00Z

[Federal Register Volume 77, Number 140 (Friday, July 20, 2012)]
[Proposed Rules]
[Pages 42677-42679]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-17560]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2012-0745; Notice No. 33-12-01-SC]

Special Conditions: General Electric CT7-2E1 Turboshaft Engine

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the General 
Electric CT7-2E1 engine model. This engine model will have a novel or 
unusual design feature which is a combination of two existing ratings 
into a new rating called ``flat 30-second and 2-minute OEI'' rating. 
This rating is intended for the continuation of flight of a multi-
engine rotorcraft after one engine becomes inoperative. 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 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 September 18, 2012.

ADDRESSES: Send comments identified by docket number FAA-2012-0745 
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: Docket Operations will post all comments it receives, 
without change, to http://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: You may read background documents or comments received 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 
this proposed rule, contact Donna Mihail, ANE-111, Engine and Propeller 
Directorate, Aircraft Certification Service, 12 New England Executive 
Park, Burlington, Massachusetts 01803-5299; telephone (781) 238-7153; 
facsimile (781) 238-7199; email dorina.mihail@faa.gov. For legal 
questions concerning this proposed rule, contact Vincent Bennett, ANE-7 
Engine and Propeller Directorate, Aircraft Certification Service, 12 
New England Executive Park, Burlington, Massachusetts 01803-5299; 
telephone (781) 238-7044; facsimile (781) 238-7055; email 
vincent.bennett@faa.gov.

[[Page 42678]]

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views to the docket. 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 received in the docket 
on or before the closing date for comments. We will consider comments 
filed late 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 September 10, 2009, General Electric applied for an amendment to 
type certificate E8NE to add the new CT7-2E1 turboshaft engine model. 
The CT7-2E1 engine model is a derivative of the CT7 engine family 
certified between 1977 and 2010. It is a free turbine turbo shaft 
designed for a transport category twin-engine helicopter. The CT7-2E1 
engine will incorporate a novel and unusual feature which is the ``flat 
30-second and 2-minute OEI'' rating. The applicant requested this 
rating to provide the increased power required for the rotorcraft 
performance. A special condition is necessary to apply additional 
requirements for the rating's definition, overspeed, controls system, 
and endurance test because the applicable airworthiness standards do 
not contain adequate or appropriate airworthiness standards to address 
this design feature.

Type Certification Basis

    Under the provisions of 14 CFR 21.101(a), GE must show that the 
model CT7-2E1 turboshaft engine meets the provisions of the applicable 
regulations in effect on the date of application, except as detailed in 
paragraphs 21.101(b) and (c). The FAA has determined the following 
certification basis for CT7-2E1 model turboshaft engine:
    1. 14 CFR part 33, ``Airworthiness Standards: Aircraft Engines'', 
dated February 1, 1965, with Amendments 1 through 20 except Sec. Sec.  
33.5(b)(4), A33.4(b)(1), and A33.4(b)(2) Amendments 1-25 applicable to 
the ``flat 30-second and 2-minute OEI'' rating. The applicant will 
voluntarily comply with Sec.  33.28, Amendments 1-28 for the EECU, FMU 
and AISBV.
    2. 14 CFR part 34, Amendments 1 through 4, Sec.  34.11 ``Standard 
for Fuel Venting Emissions''.
    Under the provisions of 14 CFR 21.101(d), if the FAA finds that the 
regulations in effect on the date of the application for the change do 
not provide adequate standards with respect to the proposed change 
because of a novel or unusual design feature, the applicant must also 
comply with special conditions, and amendments to those special 
conditions, prescribed under the provisions of Sec.  21.16, to provide 
a level of safety equal to that established by the regulations in 
effect on the date of the application for the change.
    The FAA issues special conditions, as defined by 14 CFR 11.19, 
under 14 CFR 11.38, which become part of the type certification basis 
as specified in Sec. Sec.  21.17(a)(2) or 21.101(d).
    Special conditions are initially applicable to the engine model for 
which they are issued. If the type certificate for that model is 
amended later to include another related model that incorporates the 
same or similar novel or unusual design feature, or if any other model 
already included on the same type certificate is modified to 
incorporate the same or similar novel or unusual design feature, the 
special conditions may also apply to the other model.

Novel or Unusual Design Features

    The CT7-2E1 turboshaft engine will incorporate a ``flat 30-second 
and 2-minute OEI'' rating, for use after the failure or shutdown of one 
engine, and for up to three periods of 2.5 minutes each on any one 
flight. Special conditions for the ``flat 30-second and 2-minute OEI'' 
rating are proposed to address this novel and unusual design feature. 
The special conditions are discussed below.

Discussion

    The ``flat 30-second and 2-minute OEI'' rating is equivalent in 
some regards with the 2\1/2\ min OEI rating and in other regards with 
the 30-second OEI and the 2-minute OEI ratings. However, the proposed 
rating differs from the 2\1/2\ minute OEI rating because it limits the 
number of occurrences per flight and mandates post-flight inspection 
and maintenance actions. The proposed rating is similar with the 
combined or joined 30-second OEI and 2-minute OEI ratings when they are 
equal. However, the existing standards are not adequate for this 
combination.
    Similarly with the ``flat 30-second and 2-minute OEI'' rating, the 
30-second and 2-minute OEI ratings were introduced to provide multi-
engine rotorcraft with high power for short periods of time when an 
engine becomes inoperative during critical flight conditions. Existing 
airworthiness standards for the 30-second OEI and 2-minute OEI ratings 
were established based on the assumption that the two ratings will be 
selected together as a package, and that the 30-second OEI rating is 
higher than the 2-minute OEI rating. Because the 30-second OEI rating 
was assumed higher, specific requirements were established for only 
this rating and for the 30 seconds time period. When the 30-second and 
2-minute OEI ratings are equal, these requirements must be extended to 
a total period of 2.5 minutes.
    We identified the special conditions discussed below, that are 
based on a combination of existing regulations for the 2\1/2\ minute 
OEI rating on one hand, and the 30-second and 2-minute OEI ratings on 
the other. Under the provisions of Sec.  21.101(d) the special 
conditions must provide a level of safety equal to that established by 
the regulations in effect on the date of the application for the 
change. The FAA determined that the type certification basis for CT7-
2E1 engine model is up to and including Amendment 20 of part 33. We 
also determined that the part 33 standards up to and including 
Amendment 25 contain part of the standards for the ``flat 30-second and 
2-minute OEI''. Therefore, we will not use special conditions when the 
requirements exist in later amendments, and instead we will apply these 
later amendments; refer to the above section titled ``Type 
Certification Basis''. These standards are (1) Section A33.4, 
Airworthiness Limitations Section, paragraphs (b)(1) and (b)(2) 
Amendments 1-25, and (2) Section 33.5 Instruction manual for installing 
and operating the engine, paragraph (b)(4) Amendments 1-25.
    The special conditions are in addition to the requirements of the 
30-second and 2-minute OEI ratings that remain applicable to the ``flat 
30-second and 2-minute OEI'' rating, as follows:
     The special conditions extend the standards applicable to 
the 30-second OEI or 2-minute OEI for the 2.5 minutes time duration of 
the ``flat 30-second and 2-minute OEI'' rating. We propose special 
conditions by revising the time dependent requirements of Sec. Sec.  
33.27, 33.87(a)(7), and 33.88(c). The 2.5 minutes time duration for the 
proposed rating would affect the engine structural and operational 
characteristics that are time dependent, such as the values for 
transients, time duration for stabilization to steady state, and part 
growth due to deformation. In addition, we propose special conditions 
to extend the 30-second OEI rating requirements of Sec.  33.67(d) for 
automatic availability

[[Page 42679]]

and control of the engine power, from 30 seconds to 2.5 minutes. FAA 
proposes special conditions based on Sec.  33.28(k) requirements of 
amendment 33-26, which are the same as those of Sec.  33.67(d) 
amendment 33-18.
     Special conditions are required to account for the 
proposed rating of 2.5 minutes time duration during the endurance test 
conduct. For the 30-second and 2-minute OEI the test schedule of Sec.  
33.87(f) is divided among the two ratings.
    We propose special conditions by revising the requirements of Sec.  
33.87(f) to ensure the test will be run for 2.5 minutes duration with 
no interruption.

Applicability

    As discussed above, these special conditions are applicable to GE's 
CT7-2E1 turboshaft engines. If GE applies later for a change to the 
type certificate to include another closely related model incorporating 
the same novel or unusual design feature, these special conditions 
would apply to that model as well, providing the certification basis is 
the same or contains later amendments that satisfy the certification 
basis discussed in the section titled ``Type Certification Basis''.

Conclusion

    This action affects only certain novel or unusual design features 
on the CT7-2E1 turboshaft engine. It is not a rule of general 
applicability, and it applies only to GE, who requested FAA approval of 
this engine feature.

List of Subjects in 14 CFR part 33

    Air transportation, Aircraft, Aviation safety, Safety.

    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

    Accordingly, the FAA proposes the following special conditions as 
part of the type certification basis for GE CT7-2E1 turboshaft engine.

1. Part 1 Definitions

    Unless otherwise approved by the Administrator and documented in 
the appropriate manuals and certification documents, the following 
definition applies to this special condition: ``Rated flat 30-second 
and 2-minute One Engine Inoperative (OEI) Power,'' with respect to 
rotorcraft turbine engines, means (1) a rating for which the shaft 
horsepower and associated operating limitations of the 30-second OEI 
and 2-minute OEI ratings are equal, and (2) the shaft horsepower is 
that developed under static conditions at the altitude and temperature 
for the hot day, and within the operating limitations established under 
part 33. The rating is for continuation of flight operation after the 
failure or shutdown of one engine in multiengine rotorcraft, for up to 
three periods of use no longer than 2.5 minutes each in any one flight, 
and followed by mandatory inspection and prescribed maintenance action.

2. Part 33 Requirements

    (a) In addition to the airworthiness standards in the type 
certification basis applicable to the engine and the 30-second and 2-
minute OEI ratings, the special conditions in this section apply.
    (b) Section 33.7 Engine ratings and operating limitations. Flat 30-
second and 2-minute OEI rating and operating limitations are 
established by power, torque, rotational speed, gas temperature, and 
time duration.
    (c) Section 33.27. Turbine, compressor, fan, and turbosupercharger 
rotor overspeed. The requirements applicable to 2\1/2\ minute OEI 
rating, except that following the test, the rotor may not exhibit 
conditions such as cracking or distortion which preclude continued safe 
operation.
    (d) Section 33.28 Engine controls systems. Must incorporate a 
means, or a provision for a means, for automatic availability and 
automatic control of the flat 30-second and 2-minute OEI power for the 
duration of 2.5 minutes and within the declared operating limitations.
    (e) Section 33.87 Endurance test. The requirements applicable to 
30-second and 2-minute OEI rating, except for:
    (1) The test of Sec.  33.87(a)(7) as applicable to the 2\1/2\ 
minute OEI rating. Note to paragraph (e)(1): For the purpose of 
temperature stabilization, the test period time is 2.5 minutes.
    (2) The tests in Sec.  33.87(f)(2) and (3) must be run continuously 
for the duration of 2.5 minutes, and
    (3) The tests in Sec.  33.87(f)(6) and (7) must be run continuously 
for the duration of 2.5 minutes.
    (f) Section 33.88 Engine overtemperature test. The requirements of 
Sec.  33.88(c) except that the test time is 5 minutes instead of 4 
minutes.

    Issued in Burlington, Massachusetts, on June 28, 2012.
Robert J. Ganley,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2012-17560 Filed 7-19-12; 8:45 am]
BILLING CODE 4910-13-M