DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0793; Project Identifier MCAI-2021-00372-E]
RIN 2120-AA64

Airworthiness Directives; Safran Helicopter Engines, S.A. (Type
Certificate Previously Held by Turbomeca S.A.) Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2005-12-08, which applies to Safran Helicopter Engines, S.A. (Safran
Helicopter Engines) Arrius 2B1, 2B1A, 2B1A-1, and 2B2 model turboshaft
engines. AD 2005-12-08 requires replacing the software in the engine
electronic control unit (EECU). Since the FAA issued AD 2005-12-08, the
manufacturer determined that certain previously affected EECUs are not
subject to the unsafe condition identified in AD 2005-12-08. This
proposed AD would retain the requirements of AD 2005-12-08 for engines
with a certain EECU part number (P/N) installed. This proposed AD would
also prohibit installation of an affected EECU onto any engine. The FAA
is proposing this AD to address the unsafe condition on these products.

DATES: The FAA must receive comments on this proposed AD by November 4,
2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: (202) 493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact Safran
Helicopter Engines, S.A., Avenue du 1er Mai, 40220 Tarnos, France;
phone: +33 (0) 5 59 74 45 00. You may view this service information at
the FAA, Airworthiness Products Section, Operational Safety Branch,
1200 District Avenue, Burlington, MA 01803. For information on the
availability of this material at the FAA, call (781) 238-7759.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0793; or in person at
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The AD docket contains this NPRM, the
mandatory continuing airworthiness information (MCAI), any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Wego Wang, Aviation Safety Engineer,
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone:
(781) 238-7134; fax: (781) 238-7199; email: wego.wang@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under ADDRESSES. Include "Docket No. FAA-2021-0793; Project
Identifier MCAI-2021-00372-E" at the beginning of your comments. The
most helpful comments reference a specific portion of the proposal,
explain the reason for any recommended change, and include supporting
data. The FAA will consider all comments received by the closing date
and may amend the proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact we receive about this proposed AD.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Wego
Wang, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue,
Burlington, MA 01803. Any commentary that the FAA receives which is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.

Background

The FAA issued AD 2005-12-08, Amendment 39-14124 (70 FR 34334, June
14, 2005), (AD 2005-12-08), for all Turbomeca S.A. (Turbomeca) Arrius
2B1, 2B1A, 2B1A-1, and 2B2 model turboshaft engines. AD 2005-12-08 was
prompted by a report of simultaneous loss of automatic control of both
engines of an Airbus Helicopters Deutschland (formerly Eurocopter
Deutschland) EC135 helicopter during flight. AD 2005-12-08 requires
replacing the software in the EECU. The agency issued AD 2005-12-08 to
prevent simultaneous loss of automatic control of both engines and
subsequent loss of control of the helicopter.

Actions Since AD 2005-12-08 Was Issued

Since the FAA issued AD 2005-12-08, the European Union Aviation
Safety Agency (EASA), which is the Technical Agent for the Member
States of the European Community, has issued EASA AD 2021-0088, dated
March 24, 2021.

EASA AD 2021-0088 was revised by EASA AD 2021-0088R1, dated July 26,
2021 (EASA AD 2021-0088R1) (referred to after this as "the MCAI"), to
address the unsafe condition on these products. The MCAI states:

An occurrence was reported of simultaneous loss of automatic
control in flight of both ARRIUS 2B1 engines on an EC135 T1
helicopter. Loss of automatic control would result, for each engine,
from a difference between the position datum of the fuel metering
valve and its measured position.

This condition, if not corrected, could lead to increased work
for flight crew during certain flight phases, possibly resulting in
reduced control of the helicopter.

To address this potential unsafe condition, Turbom[eacute]ca
developed mod TU80C, TU81C, TU82C and TU90C to improve the DECU
software for ARRIUS 2B1 engines without overspeed option, ARRIUS 2B1
engines with overspeed option, ARRIUS 2B1A and ARRIUS 2B2 engines,
and DGAC France issued AD F-2004-017 (later revised) to require
engine modification.

Since that [DGAC France] AD was issued, it was determined that a
DECU having a P/N which corresponds to Turbom[eacute]ca mod TU80C,
TU81C, TU82C, TU90C or later software is not affected by the
software modification requirement. DGAC France AD F-2004-017R1 did
not specifically identify any affected DECU P/N(s).

For the reason described above, this [EASA] AD retains the
requirements of DGAC France AD F-2004-017R1 (EASA approval 2004-
1618), which is superseded, and limits the required actions to
engines with an affected DECU P/N installed. This [EASA] AD also
prohibits (re)installation of affected DECU on any engine.

This [EASA] AD is revised to provide clarification on affected
and serviceable DECU.

You may obtain further information by examining the MCAI in the AD
docket at https://www.regulations.gov by searching for and locating
Docket No. FAA-2021-0793.

In addition, Turbomeca issued Mandatory Service Bulletin (MSB) No.
319 73 2082, Version D, dated June 6, 2011. The manufacturer discovered
an error in Version C of the MSB and determined that the requirement to
replace the EECU or upgrade the EECU software should be applicable to
only engines with a certain EECU P/N installed.

FAA's Determination

This product has been approved by EASA and is approved for
operation in the United States. Pursuant to our bilateral agreement
with the European Community, EASA has notified the FAA of the unsafe
condition described in the MCAI and service information. The FAA is
issuing this NPRM because the agency evaluated all the relevant
information provided by EASA and determined the unsafe condition
described previously is likely to exist or develop in other products of
the same type design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Turbomeca Mandatory Service Bulletin (MSB) No. 319
73 2080, Update No. 1, dated February 13, 2004; Turbomeca MSB No. 319
73 2081, Update No. 1, dated February 13, 2004; Turbomeca MSB No. 319
73 2082, Update No. 1, dated February 13, 2004, Version C, dated July
31, 2008, and Version D, dated June 6, 2011; and Turbomeca MSB No. 319
73 2090, Original Issue, dated February 13, 2004. This service
information specifies procedures for upgrading the EECU by either
replacing the EECU or by uploading the software to the EECU. These
documents are distinct since they apply to different engine models in
different configurations. The Director of the Federal Register
previously approved Turbomeca MSB No. 319 73 2080, Update No. 1, dated
February 13, 2004; Turbomeca MSB No. 319 73 2081, Update No. 1, dated
February 13, 2004; Turbomeca MSB No. 319 73 2082, Update No. 1, dated
February 13, 2004; and Turbomeca MSB No. 319 73 2090, Original Issue,
dated February 13, 2004 for incorporation by reference on June 29, 2005
(70 FR 34334, June 14, 2005). This service information is reasonably
available because the interested parties have access to it through
their normal course of business or by the means identified in
ADDRESSES.

Proposed AD Requirements in This NPRM

This proposed AD would retain all the requirements of AD 2005-12-
08. This proposed AD would require replacement of the EECU or upgrade
of the EECU software for engines with a certain EECU P/N installed.
This proposed AD would also prohibit installation of an affected EECU
onto any engine.

Differences Between the Proposed AD and MCAI or Service Information

EASA AD 2021-0088R1, dated July 26, 2021, uses the term digital
engine control unit (DECU), whereas the Turbomeca MSBs and this
proposed AD use EECU. These terms refer to the same part.

Turbomeca MSB No. 319 73 2080, Update No. 1, dated February 13,
2004; Turbomeca MSB No. 319 73 2081, Update No. 1, dated February 13,
2004; Turbomeca MSB No. 319 73 2082, Update No. 1, dated February 13,
2004, Version C, dated July 31, 2008, and Version D, dated June 6,
2011; and Turbomeca MSB No. 319 73 2090, Original Issue, dated February
13, 2004, instruct operators to notify Turbomeca that the EECUs have
been replaced by returning the completed compliance certificate. This
proposed AD would not mandate returning the completed compliance
certificate to Turbomeca.

EASA AD 2021-0088R1 and the Turbomeca service information reference
Arrius 2B1A_1 or Arrius 2B1A-1 model turboshaft engines, whereas this
AD references Arrius 2B1A model turboshaft engines. Arrius 2B1A_1 model
turboshaft engines are Arrius 2B1A model turboshaft engines with
modification (mod) TU45C.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 221 engines installed on helicopters of U.S. registry.

The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, Section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.

Regulatory Findings

The FAA has determined that this proposed AD would not have
federalism implications under Executive Order 13132. This proposed AD
would not have a substantial direct effect on the States, on the
relationship between the national Government and the States, or on the
distribution of power and responsibilities among the various levels of
government.

For the reasons discussed above, I certify that the proposed
regulation:

(1) Is not a "significant regulatory action" under Executive
Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive 2005-12-08, Amendment 39-14124 (70
FR 34334, June 14, 2005); and

b. Adding the following new airworthiness directive: