[Federal Register Volume 76, Number 103 (Friday, May 27, 2011)]
[Rules and Regulations]
[Pages 30819-30821]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-13008]



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  Federal Register / Vol. 76, No. 103 / Friday, May 27, 2011 / Rules 
and Regulations  

[[Page 30819]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. NE132; Special Conditions No. 33-009-SC]


Special Conditions: Turbomeca Arriel 2D Turboshaft Engine

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for Turbomeca SA model 
Arriel 2D engines. The engine model will have a novel or unusual design 
feature which is a 30-minute power rating. This rating is generally 
intended to be used for hovering at increased power for search and 
rescue missions. The applicable airworthiness regulations do not 
contain adequate or appropriate safety standards for this design 
feature. These special conditions contain the added 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 June 27, 2011.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this rule contact Marc Bouthillier, ANE-111, Engine and Propeller 
Directorate, Aircraft Certification Service, 12 New England Executive 
Park, Burlington, Massachusetts 01803-5299; telephone (781) 238-7120; 
facsimile (781) 238-7199; e-mail [email protected]. For legal 
questions concerning this 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; e-mail 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    On August 26, 2010, Turbomeca applied for type certification for a 
new model Arriel 2D turboshaft engine. This engine consists of an axial 
air intake, an axial compressor and a centrifugal compressor driven by 
a single-stage turbine, a direct-flow annular combustion chamber, and a 
single-stage free turbine which drives a reduction gear assembly 
located at the rear end. The accessory gearbox, located at the front 
end, is driven by the gas generator turbine.
    The engine will incorporate a novel or unusual design feature, 
which is a 30-minute power rating. This rating was requested by the 
applicant to support rotorcraft search and rescue missions that require 
extensive operations at high power. This type of rating is generally 
associated with multi-engine applications and has usually been named an 
all-engine-operating (AEO) rating. However, this model will be 
installed on a single engine rotorcraft, and the rating name for the 
purpose of this special condition is now 30-minute power rating. The 
number of times this new rating can be used during a flight is not 
intended to be limited.
    The applicable airworthiness standards do not contain adequate or 
appropriate airworthiness standards to address this design feature. 
Therefore, a special condition is necessary to apply additional 
requirements for rating definition, instructions for continued 
airworthiness (ICA), and endurance testing. The 30 minute time limit 
applies to each instance the rating is used; however there is no limit 
to the number of times the rating can be used during any one flight, 
and there is no cumulative time limitation. The ICA requirement is 
intended to address the unknown nature of actual rating usage and 
associated engine deterioration. The applicant is expected to make an 
assessment of the expected usage and publish ICAs and ALS limits in 
accordance with those assumptions, such that engine deterioration is 
not excessive. The endurance test requirement of 25 hours operation at 
30 minute rating is similar to several special conditions issued over 
the past 20 years addressing the same subject. It must be noted that 
test time required for the takeoff rating may not be counted toward the 
25 hours of operation required for the 30-minute rating.
    These special conditions contain the additional airworthiness 
standards necessary to establish a level of safety equivalent to the 
level that would result from compliance with the applicable standards 
of airworthiness in effect on the date of application.

Type Certification Basis

    Under the provisions of 14 CFR 21.17(a) and 21.101(a), Turbomeca 
must show that the model Arriel 2D turboshaft engine meets the 
provisions of the applicable regulations in effect on the date of 
application, unless otherwise specified by the FAA. The current 
certification basis for engines in this model series varies, being 
either 14 CFR part 33, Amendment 14 or Amendment 15. Turbomeca proposes 
a certification basis of part 33, Amendment 15. In accordance with 
Sec.  21.101(b), the FAA concurs with the Turbomeca proposal. 
Therefore, the certification basis for the Turbomeca Arriel 2D will be 
part 33, effective February 1, 1965, as amended by Amendments 33-1 
through 33-15 inclusive. The FAA has determined that the applicable 
airworthiness regulations (part 33, Amendments 1-15 inclusive) do not 
contain adequate or appropriate safety standards for the model Arriel 
2D turboshaft engine, because of a novel or unusual rating. Therefore, 
special conditions are prescribed under the provisions of 14 CFR 11.19 
and 14 CFR 21.16.
    The FAA issues special conditions, as defined by 14 CFR 11.19, in 
accordance with 14 CFR 11.38, which become part of the type 
certification basis in accordance with Sec.  21.17(a)(2) and (b).
    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 another related model that incorporates the same or 
similar novel or unusual design feature, or should any other model 
already included on the same type certificate be modified to 
incorporate the same or similar novel or unusual design feature, the 
special conditions would also apply to the other model.

Novel or Unusual Design Features

    The Turbomeca (TM) model Arriel 2D turboshaft engine will 
incorporate a novel or unusual design feature which is a 30-minute 
power rating, for use up to 30 minutes at any time between the take-off 
and landing phases of a flight.

[[Page 30820]]

This design feature is considered to be novel and unusual relative to 
the part 33 airworthiness standards.

Discussion of Comments

    Notice of proposed special conditions, Notice No. 33-11-01-SC for 
the Arriel 2D engine model was published on April 1, 2011 (76 FR 
18130). One comment letter was received.
    The commenter agreed with the special conditions for the Arriel 2D 
model only; and only as driven by program needs and because the engine 
is already compliant via similar requirements applied during EASA type 
certification. The commenter expressed several technical and regulatory 
disagreements with the special conditions, which are discussed below.
    The commenter stated disagreement with the special condition 
requirement of incorporating 25 hours of operation at the 30 minute 
rating into the Sec.  33.87 test profile. The commenter proposed to 
take credit for the 30 minute periods run at takeoff rating that is 
part of the normal test profile required by Sec.  33.87(b), thereby 
reducing the amount of test time at the new 30 minute rating. The FAA 
does not agree. The takeoff rating and other normal ratings are defined 
within 14 CFR part 1, and the associated requirements can be found in 
part 33. Takeoff rating is limited in use to a continuous period of not 
more then 5 minutes during takeoff operations. The existing Sec.  33.87 
requirements are designed to demonstrate engine durability for the 
takeoff rating which is considered a normal every flight operation, and 
is independent of any other ratings. The proposed 30 minute rating is 
not defined within part 33, but has been specifically requested by TM. 
This new rating can be used for periods of up to 30 minutes at any time 
during a flight for a variety of normal mission purposes. Also, the 
number of usages during a single flight is not limited; and its use 
does not require special maintenance actions.
    The new 30 minute rating is intended for normal mission use, 
similar to takeoff and other normal use ratings, but is different then 
limited turboshaft one-engine-inoperative (OEI) ratings. The OEI 
ratings for turboshafts, with the exception of continuous OEI, are for 
limited use during a flight, and in some cases limited cumulative use. 
We understand the Arriel 2D model is intended for a single engine 
application, and therefore has no OEI ratings; however, the FAA finds 
that the test time associated with the continuous OEI rating is an 
appropriate baseline to define additional requirements for a normal use 
30 minute rating. Therefore, engine durability using this rating must 
be demonstrated over and above the takeoff rating and other normal use 
ratings included in the rating structure. Therefore, no changes to the 
special conditions have been made in this regard.
    The commenter also states that the 25 hour requirement is 
inconsistent with Sec.  33.87 philosophies, stating that time at any 
rating validates any lower rating. The FAA does not agree. The Sec.  
33.87 test requirements are established to demonstrate engine 
durability at all normal and emergency ratings, and associated limits. 
The various test profiles incorporate specific elements to this end. 
The normal ratings all have individual elements that must be performed. 
The 30 minute rating is also a normal use rating and must also have a 
specific and independent element as part of the overall test. Any 
emergency ratings (for example, OEI) must also be demonstrated, however 
due to their limited use, these elements of the test may overlap 
certain normal rating elements found in the various test profiles. 
Therefore, no changes to the special conditions have been made in this 
regard.
    The commenter also states that the basis for 25 hours of required 
run time was not described in the special condition. The 25 hours was 
selected to be between the baseline Sec.  33.87 cumulative run time for 
takeoff rating (18.75 hours) and maximum continuous rating (45 hours). 
This requirement is weighted more heavily toward the takeoff time due 
to the definition of the rating and intended operation. Therefore, no 
changes to the special conditions have been made in this regard.

Applicability

    These special conditions are applicable to the Turbomeca model 
Arriel 2D turboshaft engine. If Turbomeca 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 may also apply to that model as well, and would be made part 
of the certification basis for that model.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of engine. It is not a rule of general applicability, and 
it affects only the applicant who applied to the FAA for approval of 
this feature on the engine product.

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 Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) issues the 
following special conditions as part of the type certification basis 
for the Turbomeca model Arriel 2D turbo shaft engine.
    1. PART 1 DEFINITION. Unless otherwise approved by the 
Administrator and documented in the appropriate manuals and 
certification documents, the following definition applies to this 
special condition: ``Rated 30 Minute Power'', means the approved shaft 
horsepower developed under static conditions at the specified altitude 
and temperature, and within the operating limitations established under 
part 33, and limited in use to periods not exceeding 30 minutes each.
    2. PART 33 REQUIREMENTS.
    (a) Sections 33.1 Applicability and 33.3 General: As applicable, 
all documentation, testing and analysis required to comply with the 
part 33 certification basis, must account for the 30 minute rating, 
limits and usage.
    (b) Section 33.4, instructions for continued airworthiness (ICA). 
In addition to the requirements of Sec.  33.4, the ICA must:
    (1) Include instructions to ensure that in-service engine 
deterioration due to rated 30 minute power usage will not be excessive, 
meaning that all other approved ratings are available within associated 
limits and assumed usage, for successive flights; and that 
deterioration will not exceed that assumed for declaring a time between 
overhaul (TBO) period.
    (i) The applicant must validate the adequacy of the maintenance 
actions required under paragraph (b)(1) above.
    (2) Include in the airworthiness limitations section (ALS), any 
mandatory inspections and serviceability limits related to the use of 
the 30-minute rating.
    (c) Section 33.87, Endurance Test. In addition to the requirements 
of Sec. Sec.  33.87(a) and 33.87(b), the overall test run must include 
a minimum of 25 hours of operation at 30 minute power and limits, 
divided into periods of 30 minutes power with alternate periods at 
maximum continuous power or less.
    (1) Modification of the Sec.  33.87 test requirements to include 
the 25 hours of operation at 30-minute power rating,

[[Page 30821]]

must be proposed by the Applicant and accepted by the FAA. Note that 
the test time required for the takeoff rating may not be counted toward 
the 25 hours of operation required for the 30-minute rating.

    Issued in Burlington, Massachusetts, on May 19, 2011.
Colleen M. D'Alessandro,
Acting Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2011-13008 Filed 5-26-11; 8:45 am]
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