[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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Rules and Regulations
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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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