Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers, 35416-35418 [2021-14271]

Download as PDF 35416 Federal Register / Vol. 86, No. 126 / Tuesday, July 6, 2021 / Proposed Rules Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206–231–3195. This material may be found in the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA–2021–0545. (2) For more information about this AD, contact Kathleen Arrigotti, Aerospace Engineer, Large Aircraft Section, International Validation Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone and fax 206–231–3218; email kathleen.arrigotti@faa.gov. Issued on June 29, 2021. Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2021–14269 Filed 7–2–21; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2021–0546; Project Identifier MCAI–2021–00387–P] RIN 2120–AA64 Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). AGENCY: The FAA proposes to supersede Airworthiness Directive (AD) 2020–25–05, which applies to all Hoffmann GmbH & Co. KG (Hoffmann) model HO–V 72 propellers. AD 2020– 25–05 requires amending the existing aircraft flight manual (AFM) with abnormal propeller vibration instructions. AD 2020–25–05 also requires visual inspection and nondestructive test (NDT) inspection of the propeller hub and, depending on the results of the inspections, replacement of the propeller hub with a part eligible for installation. AD 2020–25–05 also requires replacement of the propeller hub before exceeding 30 years since the date of manufacture. Since the FAA issued AD 2020–25–05, analyses of the inspection results showed that the 30year life limit of the propeller hub is no longer needed. This proposed AD would retain certain requirements of AD 2020– 25–05 and remove the 30-year life limit of the propeller hub. 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 August 20, 2021. jbell on DSKJLSW7X2PROD with PROPOSALS SUMMARY: VerDate Sep<11>2014 16:39 Jul 02, 2021 Jkt 253001 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 service information identified in this NPRM, contact Hoffmann GmbH & Co. KG, Ku¨pferlingstrasse 9, 83022, Rosenheim, Germany; phone: +49 0 8031 1878 0; email: info@hoffmannprop.com; website: https://hoffmannprop.com. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call (781) 238–7759. ADDRESSES: Examining the AD Docket You may examine the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA–2021–0546; 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 mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. FOR FURTHER INFORMATION CONTACT: Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238–7761; fax: (781) 238–7199; email: michael.schwetz@ 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–2021–0546; Project Identifier MCAI–2021–00387–P’’ 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 the proposal because of those comments. PO 00000 Frm 00008 Fmt 4702 Sfmt 4702 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 we receive about this proposed AD. 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 Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. Background The FAA issued AD 2020–25–05, Amendment 39–21347 (85 FR 78702, December 7, 2020), (AD 2020–25–05), for all Hoffmann model HO–V 72 propellers. AD 2020–25–05 was prompted by reports of cracks at different positions on two affected propeller hubs. AD 2020–25–05 requires amending the existing AFM with abnormal propeller vibration instructions. AD 2020–25–05 also requires visual inspection and NDT inspection of the propeller hub and, depending on the results of the inspections, replacement of the propeller hub with a part eligible for installation. AD 2020–25–05 also requires replacement of the propeller hub before exceeding 30 years since the date of manufacture or within 30 days after the effective date of AD 2020–25– 05, whichever occurs later. The agency issued AD 2020–25–05 to prevent failure of the propeller hub. E:\FR\FM\06JYP1.SGM 06JYP1 35417 Federal Register / Vol. 86, No. 126 / Tuesday, July 6, 2021 / Proposed Rules Actions Since AD 2020–25–05 Was Issued Since the FAA issued AD 2020–25– 05, the European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD 2020–0226R1, dated March 31, 2021 (referred to after this as ‘‘the MCAI’’), to address the unsafe condition on these products. The MCAI states: 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. FAA–2021–0546. In addition, Hoffmann issued Service Bulletin SB E53, Rev. D, dated February 18, 2021, to no longer specify that the propeller hub be replaced before exceeding 30 years since the date of manufacture. Proposed AD Requirements in This NPRM 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 2020–0226–E 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 action(s) during overhaul in paragraph (6) [of EASA AD]. FAA’s Determination This product has been approved by EASA and is approved for operation in the United States. Pursuant to the FAA’s bilateral agreement with the European Community, EASA has notified the FAA of the unsafe condition described in the MCAI and service information. The FAA is issuing this NPRM because the agency evaluated all the relevant information provided by EASA and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. Differences Between the Proposed AD and MCAI or Service Information 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. This service information specifies 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. This proposed AD would retain certain requirements of AD 2020–25–05. This proposed AD would no longer require that the propeller hub be replaced before exceeding 30 years since the date of manufacture or within 30 days after the effective date of AD 2020– 25–05. EASA AD 2020–0226R1, dated March 31, 2021, applies to Hoffmann HO–V 72 propellers with propeller hub HO–V 72 ( ) ( )–( )–( ) that have been used or are expected to be used for aerobatic maneuvers. This proposed AD applies to all Hoffmann model HO–V 72 propellers regardless of their use. Hoffmann Propeller GmbH & Co. KG Service Bulletin SB E53, Rev. D, dated February 18, 2021, specifies that operators must send any propeller found with a crack to Hoffmann for investigation. The service bulletin also specifies that operators must report any propeller with cracked hubs to Hoffmann. This proposed AD does not mandate sending the propeller or information to Hoffmann. Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 35 propellers installed on airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed 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 replacement that would be required based on the Cost per product Parts cost results of the proposed inspection. The agency 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: jbell on DSKJLSW7X2PROD with PROPOSALS ON-CONDITION COSTS Action Labor cost Replace propeller hub .................................................. 5 work-hours × $85 per hour = $425 ........................... Authority for This Rulemaking Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, VerDate Sep<11>2014 16:39 Jul 02, 2021 Jkt 253001 Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency’s authority. PO 00000 Frm 00009 Fmt 4702 Sfmt 4702 Parts cost $1,600 Cost per product $2,025 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 E:\FR\FM\06JYP1.SGM 06JYP1 35418 Federal Register / Vol. 86, No. 126 / Tuesday, July 6, 2021 / Proposed Rules 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 has 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 that the 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: ■ (c) Applicability This AD applies to all Hoffmann GmbH & Co. KG HO–V 72 propellers. (d) Subject Joint Aircraft System Component (JASC) Code 6114, Propeller Hub Section. (e) Unsafe Condition This AD was prompted by reports of cracks at different positions on two affected propeller hubs. The FAA is issuing this AD to prevent failure of the propeller hub. The unsafe condition, if not addressed, could result in release of the propeller, damage to the airplane, and injury to persons on the ground. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions (1) Before the next flight after December 22, 2020 (the effective date of AD 2020–25–05), amend the existing aircraft flight manual by inserting the procedure: ‘‘Abnormal propeller vibrations: As applicable, reduce engine RPM.’’ (2) Before the next flight after the effective date of this AD, and thereafter, before the next flight after any flight where abnormal propeller vibrations have been experienced, visually inspect propeller hub HO–V 72 ( ) ( )–( )–( ) for cracks using paragraph 2.1 of Hoffmann Propeller GmbH & Co. KG Service Bulletin SB E53, Rev. D, dated February 18, 2021 (the SB). (3) Within 20 flight hours after the effective date of this AD, perform a non-destructive test (NDT) inspection of propeller hub HO– V 72 ( ) ( )–()–( ) using paragraph 2.3 of the SB. (4) If, during any inspection required by paragraph (g)(2) or (3) of this AD, any crack is detected, replace propeller hub HO–V 72 ( ) ( )–( )–( ) with a part eligible for installation. (5) During each overhaul of propeller hub HO–V 72 ( ) ( )–( )–( ) after the effective date of this AD, perform an NDT inspection using paragraph 2.3 of the SB. ■ (h) Definition For the purpose of this AD, a ‘‘part eligible for installation’’ is a propeller hub HO–V 72 ( ) ( )–( )–( ) with zero hours time since new or a propeller hub HO–V 72 ( ) ( )–( )–( ) that has passed an NDT inspection using paragraph 2.3 of the SB. Hoffmann GmbH & Co. KG: Docket No. FAA–2021–0546; Project Identifier MCAI–2021–00387–P. (i) Non-Required Actions (1) Sending the propeller to Hoffmann for investigation, as contained in paragraph 2.1 of the SB, is not required by this AD. (2) Reporting propeller hubs with cracks to Hoffmann, as contained in paragraph 2.3 of the SB, is not required by this AD. (a) Comments Due Date The FAA must receive comments on this airworthiness directive (AD) by August 20, 2021. (j) Credit for Previous Actions You may take credit for the initial visual inspection and NDT inspection of the propeller hub required by paragraphs (g)(2), Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. The FAA amends § 39.13 by: a. Removing Airworthiness Directive AD 2020–25–05, Amendment 39–21347 (85 FR 78702, December 7, 2020); and ■ b. Adding the following new airworthiness directive: ■ jbell on DSKJLSW7X2PROD with PROPOSALS (b) Affected ADs This AD replaces AD 2020–25–05, Amendment 39–21347 (85 FR 78702, December 7, 2020). VerDate Sep<11>2014 16:39 Jul 02, 2021 Jkt 253001 PO 00000 Frm 00010 Fmt 4702 Sfmt 9990 (3), and (5) of this AD if you performed any of these actions before the effective date of this AD using Hoffmann Propeller GmbH & Co. KG SB E53 Rev. A, dated October 9, 2020; Rev. B, dated October 14, 2020; or Rev. C, dated December 9, 2020. (k) Special Flight Permit A special flight permit may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the airplane to a service facility to perform the NDT inspection. Special flight permits are prohibited to perform the visual inspection of the propeller hub. (l) Alternative Methods of Compliance (AMOCs) (1) The Manager, Boston ACO Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in Related Information. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/ certificate holding district office. (m) Related Information (1) For more information about this AD, contact Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: (781) 238–7761; fax: (781) 238–7199; email: michael.schwetz@faa.gov. (2) Refer to European Union Aviation Safety Agency (EASA) AD 2020–0226R1, dated March 31, 2021, for more information. You may examine the EASA AD in the AD docket at https://www.regulations.gov by searching for and locating it in Docket No. FAA–2021–0546. (3) For service information identified in this AD, contact Hoffmann GmbH & Co. KG, Ku¨pferlingstrasse 9, 83022, Rosenheim, Germany; phone: +49 0 8031 1878 0; email: info@hoffmann-prop.com; website: https:// hoffmann-prop.com. You may view this referenced service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call (781) 238–7759. Issued on June 29, 2021. Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2021–14271 Filed 7–2–21; 8:45 am] BILLING CODE 4910–13–P E:\FR\FM\06JYP1.SGM 06JYP1

Agencies

[Federal Register Volume 86, Number 126 (Tuesday, July 6, 2021)]
[Proposed Rules]
[Pages 35416-35418]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-14271]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0546; Project Identifier MCAI-2021-00387-P]
RIN 2120-AA64


Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2020-25-05, which applies to all Hoffmann GmbH & Co. KG (Hoffmann) 
model HO-V 72 propellers. AD 2020-25-05 requires amending the existing 
aircraft flight manual (AFM) with abnormal propeller vibration 
instructions. AD 2020-25-05 also requires visual inspection and non-
destructive test (NDT) inspection of the propeller hub and, depending 
on the results of the inspections, replacement of the propeller hub 
with a part eligible for installation. AD 2020-25-05 also requires 
replacement of the propeller hub before exceeding 30 years since the 
date of manufacture. Since the FAA issued AD 2020-25-05, analyses of 
the inspection results showed that the 30-year life limit of the 
propeller hub is no longer needed. This proposed AD would retain 
certain requirements of AD 2020-25-05 and remove the 30-year life limit 
of the propeller hub. 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 August 20, 
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 service information identified in this NPRM, contact Hoffmann 
GmbH & Co. KG, K[uuml]pferlingstrasse 9, 83022, Rosenheim, Germany; 
phone: +49 0 8031 1878 0; email: prop.com">[email protected]prop.com; website: 
prop.com">https://hoffmann-prop.com. You may view this service information at the 
FAA, Airworthiness Products Section, Operational Safety Branch, 1200 
District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call (781) 238-7759.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0546; 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 
mandatory continuing airworthiness information (MCAI), any comments 
received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Michael Schwetz, Aviation Safety 
Engineer, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA 
01803; phone: (781) 238-7761; fax: (781) 238-7199; email: 
[email protected].

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-2021-0546; Project Identifier 
MCAI-2021-00387-P'' 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 
the 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 we receive about this proposed AD.

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 
Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, FAA, 1200 
District Avenue, Burlington, MA 01803. Any commentary that the FAA 
receives which is not specifically designated as CBI will be placed in 
the public docket for this rulemaking.

Background

    The FAA issued AD 2020-25-05, Amendment 39-21347 (85 FR 78702, 
December 7, 2020), (AD 2020-25-05), for all Hoffmann model HO-V 72 
propellers. AD 2020-25-05 was prompted by reports of cracks at 
different positions on two affected propeller hubs. AD 2020-25-05 
requires amending the existing AFM with abnormal propeller vibration 
instructions. AD 2020-25-05 also requires visual inspection and NDT 
inspection of the propeller hub and, depending on the results of the 
inspections, replacement of the propeller hub with a part eligible for 
installation. AD 2020-25-05 also requires replacement of the propeller 
hub before exceeding 30 years since the date of manufacture or within 
30 days after the effective date of AD 2020-25-05, whichever occurs 
later. The agency issued AD 2020-25-05 to prevent failure of the 
propeller hub.

[[Page 35417]]

Actions Since AD 2020-25-05 Was Issued

    Since the FAA issued AD 2020-25-05, the European Union Aviation 
Safety Agency (EASA), which is the Technical Agent for the Member 
States of the European Community, has issued EASA AD 2020-0226R1, dated 
March 31, 2021 (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 2020-
0226-E 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 action(s) 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. FAA-2021-0546.
    In addition, Hoffmann issued Service Bulletin SB E53, Rev. D, dated 
February 18, 2021, to no longer specify that the propeller hub be 
replaced before exceeding 30 years since the date of manufacture.

FAA's Determination

    This product has been approved by EASA and is approved for 
operation in the United States. Pursuant to the FAA's bilateral 
agreement with the European Community, EASA has notified the FAA of the 
unsafe condition described in the MCAI and service information. The FAA 
is issuing this NPRM because the agency evaluated all the relevant 
information provided by EASA and determined the unsafe condition 
described previously is likely to exist or develop in other products of 
the same type design.

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. This service information 
specifies 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.

Proposed AD Requirements in This NPRM

    This proposed AD would retain certain requirements of AD 2020-25-
05. This proposed AD would no longer require that the propeller hub be 
replaced before exceeding 30 years since the date of manufacture or 
within 30 days after the effective date of AD 2020-25-05.

Differences Between the Proposed AD and MCAI or Service Information

    EASA AD 2020-0226R1, dated March 31, 2021, applies to Hoffmann HO-V 
72 propellers with propeller hub HO-V 72 ( ) ( )-( )-( ) that have been 
used or are expected to be used for aerobatic maneuvers. This proposed 
AD applies to all Hoffmann model HO-V 72 propellers regardless of their 
use.
    Hoffmann Propeller GmbH & Co. KG Service Bulletin SB E53, Rev. D, 
dated February 18, 2021, specifies that operators must send any 
propeller found with a crack to Hoffmann for investigation. The service 
bulletin also specifies that operators must report any propeller with 
cracked hubs to Hoffmann. This proposed AD does not mandate sending the 
propeller or information to Hoffmann.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 35 propellers installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Amend AFM.............................  1 work-hour x $85 per                 $0             $85          $2,975
                                         hour = $85.
Visually inspect propeller hub........  1 work-hour x $85 per                  0              85           2,975
                                         hour = $85.
NDT inspect propeller hub.............  8 work-hours x $85 per                 0             680          23,800
                                         hour = $680.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary 
replacement that would be required based on the results of the proposed 
inspection. The agency has no way of determining the number of aircraft 
that might need this replacement:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Replace propeller hub.........................  5 work-hours x $85 per hour =             $1,600          $2,025
                                                 $425.
----------------------------------------------------------------------------------------------------------------

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

[[Page 35418]]

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 has 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 that the 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

0
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]

0
2. The FAA amends Sec.  39.13 by:
0
a. Removing Airworthiness Directive AD 2020-25-05, Amendment 39-21347 
(85 FR 78702, December 7, 2020); and
0
b. Adding the following new airworthiness directive:

Hoffmann GmbH & Co. KG: Docket No. FAA-2021-0546; Project Identifier 
MCAI-2021-00387-P.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by August 20, 2021.

(b) Affected ADs

    This AD replaces AD 2020-25-05, Amendment 39-21347 (85 FR 78702, 
December 7, 2020).

(c) Applicability

    This AD applies to all Hoffmann GmbH & Co. KG HO-V 72 
propellers.

(d) Subject

    Joint Aircraft System Component (JASC) Code 6114, Propeller Hub 
Section.

(e) Unsafe Condition

    This AD was prompted by reports of cracks at different positions 
on two affected propeller hubs. The FAA is issuing this AD to 
prevent failure of the propeller hub. The unsafe condition, if not 
addressed, could result in release of the propeller, damage to the 
airplane, and injury to persons on the ground.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    (1) Before the next flight after December 22, 2020 (the 
effective date of AD 2020-25-05), amend the existing aircraft flight 
manual by inserting the procedure: ``Abnormal propeller vibrations: 
As applicable, reduce engine RPM.''
    (2) Before the next flight after the effective date of this AD, 
and thereafter, before the next flight after any flight where 
abnormal propeller vibrations have been experienced, visually 
inspect propeller hub HO-V 72 ( ) ( )-( )-( ) for cracks using 
paragraph 2.1 of Hoffmann Propeller GmbH & Co. KG Service Bulletin 
SB E53, Rev. D, dated February 18, 2021 (the SB).
    (3) Within 20 flight hours after the effective date of this AD, 
perform a non-destructive test (NDT) inspection of propeller hub HO-
V 72 ( ) ( )-()-( ) using paragraph 2.3 of the SB.
    (4) If, during any inspection required by paragraph (g)(2) or 
(3) of this AD, any crack is detected, replace propeller hub HO-V 72 
( ) ( )-( )-( ) with a part eligible for installation.
    (5) During each overhaul of propeller hub HO-V 72 ( ) ( )-( )-( 
) after the effective date of this AD, perform an NDT inspection 
using paragraph 2.3 of the SB.

(h) Definition

    For the purpose of this AD, a ``part eligible for installation'' 
is a propeller hub HO-V 72 ( ) ( )-( )-( ) with zero hours time 
since new or a propeller hub HO-V 72 ( ) ( )-( )-( ) that has passed 
an NDT inspection using paragraph 2.3 of the SB.

(i) Non-Required Actions

    (1) Sending the propeller to Hoffmann for investigation, as 
contained in paragraph 2.1 of the SB, is not required by this AD.
    (2) Reporting propeller hubs with cracks to Hoffmann, as 
contained in paragraph 2.3 of the SB, is not required by this AD.

(j) Credit for Previous Actions

    You may take credit for the initial visual inspection and NDT 
inspection of the propeller hub required by paragraphs (g)(2), (3), 
and (5) of this AD if you performed any of these actions before the 
effective date of this AD using Hoffmann Propeller GmbH & Co. KG SB 
E53 Rev. A, dated October 9, 2020; Rev. B, dated October 14, 2020; 
or Rev. C, dated December 9, 2020.

(k) Special Flight Permit

    A special flight permit may be issued in accordance with 14 CFR 
21.197 and 21.199 to operate the airplane to a service facility to 
perform the NDT inspection. Special flight permits are prohibited to 
perform the visual inspection of the propeller hub.

(l) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Boston ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in Related Information.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(m) Related Information

    (1) For more information about this AD, contact Michael Schwetz, 
Aviation Safety Engineer, Boston ACO Branch, FAA, 1200 District 
Avenue, Burlington, MA 01803; phone: (781) 238-7761; fax: (781) 238-
7199; email: [email protected].
    (2) Refer to European Union Aviation Safety Agency (EASA) AD 
2020-0226R1, dated March 31, 2021, for more information. You may 
examine the EASA AD in the AD docket at https://www.regulations.gov 
by searching for and locating it in Docket No. FAA-2021-0546.
    (3) For service information identified in this AD, contact 
Hoffmann GmbH & Co. KG, K[uuml]pferlingstrasse 9, 83022, Rosenheim, 
Germany; phone: +49 0 8031 1878 0; email: prop.com">[email protected]prop.com; 
website: prop.com">https://hoffmann-prop.com. You may view this referenced 
service information at the FAA, Airworthiness Products Section, 
Operational Safety Branch, 1200 District Avenue, Burlington, MA 
01803. For information on the availability of this material at the 
FAA, call (781) 238-7759.

    Issued on June 29, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-14271 Filed 7-2-21; 8:45 am]
BILLING CODE 4910-13-P

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