DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0335; Project Identifier MCAI-2020-01665-R;
Amendment 39-21632; AD 2021-14-05]
RIN 2120-AA64

Airworthiness Directives; Airbus Helicopters Deutschland GmbH
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
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. This 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 AD requires inspections to determine if any
bolted main rotor blades are installed, and replacement of the affected
main rotor blades. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective August 18, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain document listed in this AD as of August 18, 2021.

ADDRESSES: For service information identified in this final rule,
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/-support.html. You may view
the referenced service information at the FAA, Office of the Regional
Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort
Worth, TX 76177. Service information that is incorporated by reference
is also available at https://www.regulations.gov by searching for and
locating Docket No. FAA-2021-0335.

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 final rule, the
Luftfahrt-Bundesamt AD, any comments received, and other information.
The street address for Docket Operations is U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

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:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all 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. The
NPRM published in the Federal Register on April 26, 2021 (86 FR 21965).
In the NPRM, the FAA proposed to require inspections to determine if
any bolted main rotor blades are installed, and replacement of the
affected main rotor blades. The NPRM was prompted by a report of sudden
severe vibrations and a cracked open blade trailing edge caused by a
loosened lead inner weight.
German AD D-2005-115, effective March 15, 2005 (German AD D-2005-
115), issued by Luftfahrt-Bundesamt, which is the aviation authority
for Germany, was issued 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, German AD D-2005-115 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.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the NPRM or on the determination of
the costs.

Conclusion

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
reviewed the relevant data and determined that air safety requires
adopting this AD as proposed. Accordingly, the FAA is issuing this AD
to address the unsafe condition on these helicopters. Except for minor
editorial changes, this AD is adopted as proposed in the NPRM.

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.

Costs of Compliance

The FAA estimates that this AD affects 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 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 helicopters identified in this rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) Will 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 Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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: