DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0335; Project Identifier MCAI-2020-01665-R]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters Deutschland GmbH 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 all Airbus Helicopters Deutschland GmbH MBB-BK 117 A-1, MBB-BK 117
A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1
helicopters. This proposed AD was prompted by a report of sudden severe
vibrations and a cracked open blade trailing edge caused by a loosened
lead inner weight. This proposed AD would require inspections to
determine if any bolted main rotor blades are installed, and
replacement of the affected main rotor blades. 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 June 10,
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 between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact Airbus
Helicopters, 2701 N Forum Drive, Grand Prairie, TX 75052; phone: 972-
641-0000 or 800-232-0323; fax: 972-641-3775; or at https://www.airbus.com/
helicopters/services/technical-support.html. You may
view this service information 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.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0335; 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
Luftfahrt-Bundesamt AD, any comments received, and other information.
The street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Kathleen Arrigotti, Aerospace
Engineer, Large Aircraft Section, International Validation Branch, FAA,
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3218; email: kathleen.arrigotti@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-2021-0335; Project Identifier
MCAI-2020-01665-R" 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 NPRM.

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
Kathleen Arrigotti, Aerospace Engineer, Large Aircraft Section,
International Validation Branch, FAA, 2200 South 216th St., Des Moines,
WA 98198; phone and fax: 206-231-3218; email:
kathleen.arrigotti@faa.gov. Any commentary that the FAA receives which
is not specifically designated as CBI will be placed in the public
docket for this rulemaking.

Background

Luftfahrt-Bundesamt, which is the aviation authority for Germany,
has issued German AD D-2005-115, effective March 15, 2005, to correct
an unsafe condition for Eurocopter Deutschland (now Airbus Helicopters
Deutschland GmbH) Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4,
MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters.
Luftfahrt-Bundesamt advises that during the flight of a BK117 severe
vibrations suddenly occurred, stemming from a cracked open blade
trailing edge, which was traced to a loosened lead inner weight bolt.
Additional inspection revealed extreme cavities of the lead weight
resulting from the bolting process, which was performed as a repair for
main rotor blades with bulging in the area of the lead inner weights.
This condition, if not addressed, could result in loss of control of
the helicopter.

Accordingly, the Luftfahrt-Bundesamt AD requires an inspection and
log card review to determine if any bolted main
rotor blades are installed, and replacement of the affected main rotor
blades.

FAA's Determination

These helicopters have been approved by the aviation authority of
Germany and are approved for operation in the United States. Pursuant
to the FAA's bilateral agreement with Germany (now a member of the
European Union), Luftfahrt-Bundesamt, its technical representative, has
notified the FAA of the unsafe condition described in its AD. The FAA
is proposing this AD after evaluating all known relevant information
and determining that the unsafe condition described previously is
likely to exist or develop on other helicopters of the same type
design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Eurocopter Alert Service Bulletin No. ASB-MBB-
BK117-10-125 dated February 14, 2005. This service information
specifies procedures for an inspection (for cracking of the paint) and
log card review (for a certain entry or equivalent) to determine if any
bolted main rotor blades (i.e., main rotor blades with bolted lead
inner weights) are installed, and replacement of the affected main
rotor blades.

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 the ADDRESSES section.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified
in the service information already described.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 44 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.

Estimated Costs for Required Actions

The FAA estimates the following costs to do any necessary on-
condition replacements that would be required based on the results of
any required actions. The FAA has no way of determining the number of
helicopters that might need these on-condition replacements:

Estimated Costs of On-Condition Actions

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, 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: