DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0450; Project Identifier 2017-SW-100-AD]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters Deutschland GmbH
(AHD) Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for Airbus Helicopters Deutschland GmbH (AHD) Model MBB-BK 117 D-2
helicopters. This proposed AD was prompted by the discovery that
certain parts that are approved for installation on multiple helicopter
models are life limited parts when installed on Model MBB-BK 117 D-2
helicopters and some helicopter delivery documents excluded the life
limit information. This proposed AD would require determining the total
hours time-in-service (TIS) of a certain part-numbered rotor mast nut
and re-identifying a certain part-numbered rotor mast nut. This
proposed AD would also require establishing a life limit for a certain
part-numbered rotor mast nut and helical gear support, and removing
each part from service before reaching its life limit. Additionally,
this proposed AD would require replacing a certain part-numbered main
gearbox (MGB) with a not affected MGB as specified in a European
Aviation Safety Agency (now European Union Aviation Safety Agency)
(EASA) AD, which is proposed for incorporation by reference (IBR). 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 July 22,
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 material that is proposed for IBR in this AD, contact EASA,
Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221 8999
000; email ADs@easa.europa.eu; internet www.easa.europa.eu. You may
find this material on the EASA website at https://ad.easa.europa.eu.
You may view this material at the FAA, Office of the Regional Counsel,
Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX
76177. For information on the availability of this material at the FAA,
call (817) 222-5110. It is also available in the AD docket on the
internet at https://www.regulations.gov by searching for and locating
Docket No. FAA-2021-0450.

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2021-0450;
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, any comments received, and other
information. The street address for Docket Operations is listed above.
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Rao Edupuganti, Aerospace Engineer,
Dynamic Systems Section, Technical Innovation Policy Branch, Policy &
Innovation Division, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177;
telephone (817) 222-5110; email rao.edupuganti@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include "Docket No. FAA-2021-0450; Project Identifier
2017-SW-100-AD" 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
this 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 received about this proposal.

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 Rao
Edupuganti, Aerospace Engineer, Dynamic Systems Section, Technical
Innovation Policy Branch, Policy & Innovation Division, FAA, 10101
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-5110; email
rao.edupuganti@faa.gov. Any commentary that the FAA receives that is
not specifically designated as CBI will be placed in the public docket
for this rulemaking.

Background

EASA, which is the Technical Agent for the Member States of the
European Union, has issued EASA AD 2017-0037, dated February 22, 2017
(EASA AD 2017-0037), to correct an unsafe condition for Airbus
Helicopters Deutschland GmbH (formerly Eurocopter Deutschland GmbH),
Airbus Helicopters Inc. (formerly American Eurocopter LLC) Model MBB-BK
117 D-2 and MBB-BK117 D-2m helicopters.

This proposed AD was prompted by the discovery that certain parts
that are approved for installation on multiple helicopter models are
life limited parts when installed on Model MBB-BK 117 D-2 helicopters
and some helicopter delivery documents excluded the life limit
information. The FAA is proposing this AD to address an unsafe
condition on these products. See EASA AD 2017-0037 for additional
background information.

Related Service Information Under 1 CFR Part 51

EASA AD 2017-0037 requires establishing a life limit for rotor mast
nut part number (P/N) D632K1133-201 and helical gear support P/N
D632K1113-201, and replacing these parts before exceeding their life
limit. EASA AD 2017-0037 also requires replacing each rotor mast nut P/
N D632K1133-201 for which the hours time-in-service (TIS) are unknown
and replacing certain part-numbered rotor mast nuts before accumulating
3,708 hours TIS since first installation on a helicopter. EASA AD 2017-
0037 requires re-identifying each rotor mast nut P/N 117-12133-01 to P/
N D632K1133-201 by following the specified service information. EASA AD
2017-0037 requires replacing any MGB P/N D632K1001-051 with serial
number (S/N) D2-0001 up to D2-0108 inclusive, D2-0123, D2-0126, D2-
0127, or D2-0130 up to D2-0136 inclusive with a not affected MGB before
the affected MGB accumulates 3,708 hours TIS. EASA AD 2017-0037 also
prohibits installing an affected rotor mast nut or an affected MGB that
has accumulated more than 3,708 hours TIS since first installation on a
helicopter. Additionally, EASA AD 2017-0037 requires revising the
Aircraft Maintenance Program (AMP).

This material is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section.

Other Related Service Information

The FAA reviewed Airbus Helicopters Alert Service Bulletin MBB-
BK117 D-2-63A-001, Revision 0, dated December 1, 2016 (ASB 63A-001),
which is not incorporated by reference, which specifies procedures for
re-identifying the rotor mast nut by using a vibrograph, crossing out
the old P/N and marking the new P/N on the outer surface, engraving the
letter "A" behind the S/N of each part, and updating the historical
record and log card to confirm compliance with ASB 63A-001. ASB 63A-001
also specifies during the next MGB overhaul, making an entry in the log
card to confirm re-identification of the helical gear support, and
annotating the S/N of the helical gear support.

FAA's Determination and Requirements of This Proposed AD

These products have been approved by the aviation authority of
another country, and are approved for operation in the United States.
Pursuant to the bilateral agreement with the State of Design Authority,
the FAA has been notified of the unsafe condition described in EASA AD
2017-0037. The FAA is proposing this AD after evaluating all the
relevant information and determining the unsafe condition described
previously is likely to exist or develop in other products of the same
type design.

Proposed AD Requirements

This proposed AD would require accomplishing the actions specified
in EASA AD 2017-0037, described previously, as incorporated by
reference, except for any differences identified as exceptions in the
regulatory text of this proposed AD and except as discussed under
"Differences Between this Proposed AD and the EASA AD."

Explanation of Required Compliance Information

In the FAA's ongoing efforts to improve the efficiency of the AD
process, the FAA initially worked with Airbus and EASA to develop a
process to use certain EASA ADs as the primary source of information
for compliance with requirements for corresponding FAA ADs. The FAA has
since coordinated with other manufacturers and civil aviation
authorities (CAAs) to use this process. As a result, EASA AD 2017-0037
will be incorporated by reference in the FAA final rule. This proposed
AD would, therefore, require compliance with EASA AD 2017-0037
in its entirety, through that incorporation, except for any differences
identified as exceptions in the regulatory text of this proposed AD.
Using common terms that are the same as the heading of a particular
section in the EASA AD does not mean that operators need comply only
with that section. For example, where the AD requirement refers to
"all required actions and compliance times," compliance with this AD
requirement is not limited to the section titled "Required Action(s)
and Compliance Time(s)" in the EASA AD. Service information specified
in EASA AD 2017-0037 that is required for compliance with EASA AD 2017-
0037 will be available on the internet at https://www.regulations.gov
by searching for and locating Docket No. FAA-2021-0450 after the FAA
final rule is published.

Differences Between This Proposed AD and the EASA AD

EASA AD 2017-0037 applies to Model MBB-BK117 D-2 and D2m
helicopters, whereas this proposed AD would only apply to Model MBB-
BK117 D-2 helicopters because Model D-2m is not FAA type-certificated.
If the total hours TIS for an affected rotor mast nut cannot be
determined, this proposed AD would require removing the rotor mast nut
from service before further flight, whereas EASA AD 2017-0037 does not
contain this requirement. EASA AD 2017-0037 requires using a vibrograph
to re-identify certain rotor mast nuts, whereas this proposed AD would
require using a vibro etch instead. EASA AD 2017-0037 requires
replacing certain parts, whereas this proposed AD would require
removing certain parts from service instead. EASA AD 2017-0037 requires
revising the AMP, whereas this proposed AD would not.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 30 helicopters of U.S. Registry. Labor rates are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates the
following costs to comply with this proposed AD.

Determining the total hours TIS on an affected rotor mast nut would
take about 1 work-hour for an estimated cost of $85 per helicopter and
$2,550 for the U.S. fleet.

Re-identifying a rotor mast nut would take about 1.5 work-hours for
an estimated cost of $128 per rotor mast nut.

Replacing a rotor mast nut would take about 6 work-hours and parts
would cost about $5,351 for an estimated cost of $5,861 per rotor mast
nut.

Replacing a main gearbox, which includes replacing the helical gear
support, would take about 42 work-hours and parts would cost about
$295,000 (overhauled) for an estimated cost of $298,570.

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 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 this 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 adding the following new airworthiness
directive: