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Federal Register / Vol. 86, No. 171 / Wednesday, September 8, 2021 / Rules and Regulations S/N D20001 up to D20108 inclusive, D20123, D20126, D20127, or D2
0130 up to D20136 inclusive with a not affected MGB before the affected MGB
accumulates 3,708 hours TIS. EASA AD
20170037 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
20170037 requires revising the Aircraft Maintenance Program AMP.
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.

Determining the total hours TIS on an affected rotor mast nut takes 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 takes about 1.5 work-hours for an estimated cost of $128 per rotor mast nut.
Replacing a rotor mast nut takes about 6 work-hours and parts cost about $5,351 for an estimated cost of $5,861
per rotor mast nut.
Replacing a MGB, which includes replacing the helical gear support, takes about 42 work-hours and parts cost about $295,000 overhauled for an estimated cost of $298,570.

Other Related Service Information The FAA reviewed Airbus Helicopters Alert Service Bulletin MBBBK117 D
263A001, Revision 0, dated December 1, 2016 ASB 63A001, 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 63A001. ASB
63A001 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.

Authority for This Rulemaking Title 49 of the United States Code specifies the FAAs 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 Agencys 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.

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Differences Between This AD and EASA
AD 20170037
EASA AD 20170037 applies to Model MBBBK117 D2 and D2m helicopters, whereas this AD only applies to Model MBBBK117 D2
helicopters because Model D2m is not FAA type-certificated. If the total hours TIS for an affected rotor mast nut cannot be determined, this AD requires removing the rotor mast nut from service before further flight, whereas EASA AD 20170037 does not contain this requirement. EASA AD 20170037
requires using a vibrograph to reidentify certain rotor mast nuts, whereas this AD requires using a vibro etch instead. EASA AD 20170037 requires replacing certain parts, whereas this AD
requires removing certain parts from service instead. EASA AD 20170037
requires revising the AMP, whereas this AD does not.
Costs of Compliance The FAA estimates that this AD
affects 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 AD.

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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.

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The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:

Authority: 49 U.S.C. 106g, 40113, 44701.
39.13

Amended
2. The FAA amends 39.13 by adding the following new airworthiness directive:

20211617 Airbus Helicopters Deutschland GmbH AHD: Amendment 3921680; Docket No. FAA20210450;
Project Identifier 2017SW100AD.
a Effective Date This airworthiness directive AD is effective October 13, 2021.
b Affected ADs None.
c Applicability This AD applies to Airbus Helicopters Deutschland GmbH AHD Model MBBBK
117 D2 helicopters, certificated in any category, with an affected main gearbox or affected rotor mast nut as identified in Note 1 of European Aviation Safety Agency now European Union Aviation Safety Agency EASA AD 20170037, dated February 22, 2017 EASA AD 20170037 installed.
d Subject Joint Aircraft Service Component JASC
Code: 6200 Main gearbox.
e Unsafe Condition This 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 MBBBK 117 D2 helicopters and some helicopter delivery documents excluded the life limit information. The FAA
is issuing this AD to prevent certain parts from remaining in service beyond their fatigue life. The unsafe condition, if not addressed, could result in failure of the part and loss of control of the helicopter.
f Compliance Comply with this AD within the compliance times specified, unless already done.
g Requirements Except as specified in paragraph h of this AD: Comply with all required actions and compliance times specified in, and in accordance with, EASA AD 20170037.
h Exceptions to EASA AD 20170037
1 Where EASA AD 20170037 refers to its effective date, this AD requires using the effective date of this AD.

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