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Federal Register / Vol. 86, No. 231 / Monday, December 6, 2021 / Rules and Regulations
referred to after this as the MCAI, to address the unsafe condition on these products. The MCAI states:
Cracks have been reported at different positions on two affected parts, both installed on Slingsby T67 Firefly aeroplanes. One crack was found during scheduled inspection, the other crack during an unscheduled inspection after abnormal vibrations occurred. Both cases are under investigation by Hoffmann Propeller.
This condition, if not detected and corrected, could lead to in-flight propeller detachment, possibly resulting in damage to the airplane and/or injury to persons on the ground.
To address this potential unsafe condition, Hoffmann issued the SB, providing applicable instructions.
For the reasons described above, EASA
issued Emergency AD 20200226E to require inspections of affected parts and, depending on findings, replacement, and introduces a life limit for affected parts. That EASA AD also required, for certain aeroplanes, amendment of the applicable Aircraft Flight Manual AFM.
Since that EASA AD was issued, recent analyses of inspection results showed that the life limit of 30 years is no longer necessary and Hoffmann Propeller issued Revision D of the SB accordingly.

This EASA AD is revised to delete the life limit and to introduce a clarification for corrective actions during overhaul in paragraph 6 of EASA AD.

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.
FAA20210546.
Discussion of Final Airworthiness Directive Comments The FAA received comments from one individual commenter. The individual commenter supported the NPRM without change.
Clarification of Required Actions The FAA revised paragraph g, Required Actions, of this AD by clarifying that the propeller hub must be replaced with a part eligible for installation if any crack is detected during an overhaul inspection.
Conclusion The FAA reviewed the relevant data, considered the comment received, and
determined that air safety requires adopting the AD as proposed.
Accordingly, the FAA is issuing this AD
to address the unsafe condition on these products. This AD is adopted as proposed in the NPRM.
Related Service Information Under 1
CFR Part 51
The FAA reviewed Hoffmann Propeller GmbH & Co. KG Service Bulletin SB E53, Rev. D, dated February 18, 2021. The service bulletin describes procedures for visual and NDT
inspections of the propeller hub for cracks. 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.
Costs of Compliance The FAA estimates that this AD
affects 35 propellers installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this AD:

ESTIMATED COSTS
Action
Labor cost
Amend AFM
Visually inspect propeller hub
NDT inspect propeller hub

1 work-hour $85 per hour = $85
1 work-hour $85 per hour = $85
8 work-hours $85 per hour = $680

The FAA estimates the following costs to do any necessary replacements that would be required based on the
Cost per product
Parts cost
results of the mandated inspections. The FAA has no way of determining the
$0
0 0

$85
85
680

Cost on U.S.
operators $2,975
2,975
23,800

number of aircraft that might need this replacement:

ON-CONDITION COSTS
Action
Labor cost
Replace propeller hub

5 work-hours $85 per hour = $425

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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
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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 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
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Parts cost $1,600

Cost per product $2,025

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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