Document ID: FAA-2022-0980-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: Hoffmann GmbH and Co. KG Propellers
Posted Date: 2022-08-01T04:00Z

[Federal Register Volume 87, Number 146 (Monday, August 1, 2022)]
[Proposed Rules]
[Pages 46903-46906]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-16192]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0980; Project Identifier MCAI-2022-00448-P]
RIN 2120-AA64

Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2021-23-17, which applies to all Hoffmann GmbH & Co. KG (Hoffmann) 
model HO-V 72 propellers. AD 2021-23-17 requires amending the existing 
aircraft flight manual (AFM) by inserting abnormal propeller vibration 
instructions, 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. Since the FAA issued AD 2021-23-17, further investigation 
by the manufacturer revealed that cracks found on propeller hubs likely 
resulted from propeller blade retention nuts that were not tightened 
using published service information during blade installation. This 
proposed AD would retain the required actions of AD 2021-23-17. This 
proposed AD would also require a maintenance records review and, 
depending on the results of the maintenance records review, tightening 
of each propeller blade retention nut to specific torque values. 
Depending on the results of the maintenance records review, this 
proposed AD would require physically inspecting the propeller blade for 
shake. If any axial play is detected during the performance of the 
inspection, this proposed AD would require the removal of the propeller 
from service and the performance of an NDT inspection 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 September 
15, 2022.

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 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 (817) 222-5110.

Examining the AD Docket

    You may examine the AD docket at www.regulations.gov by searching 
for and locating Docket No. FAA-2022-0980; 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; 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-2022-0980; Project Identifier 
MCAI-2022-00448-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 
www.regulations.gov, including any personal information you provide. 
The

[[Page 46904]]

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 2021-23-17, Amendment 39-21815 (86 FR 68905, 
December 6, 2021), (AD 2021-23-17), for all Hoffmann GmbH & Co. KG 
model HO-V 72 propellers. AD 2021-23-17 was prompted by reports of 
cracks at different positions on two affected propeller hubs. AD 2021-
23-17 requires amending the existing AFM by inserting abnormal 
propeller vibration instructions, 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. 
The agency issued AD 2021-23-17 to prevent failure of the propeller 
hub.

Actions Since AD 2021-23-17 Was Issued

    Since the FAA issued AD 2021-23-17, the European Union Aviation 
Safety Agency (EASA), which is the Technical Agent for the Member 
States of the European Community, has issued EASA AD 2022-0061, dated 
April 4, 2022 (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. 
Subsequent investigation determined that improper tightening of 
blade nuts has caused or contributed to those events.
    This condition, if not detected and corrected, could lead to in-
flight propeller detachment, possibly resulting in damage to the 
aeroplane and/or injury to persons on the ground.
    To address this potential unsafe condition, Hoffmann Propeller 
issued the SB, providing applicable instructions, and EASA issued 
Emergency AD 2020-0226-E (later revised [to EASA AD 2020-0226R1]) to 
require inspections of affected parts and, depending on findings, 
replacement. That AD also required, for certain aeroplanes, 
amendment of the applicable Aircraft Flight Manual (AFM).
    Since that [EASA] AD was issued, further investigation revealed 
that not all propeller blade nuts were tightened in accordance with 
the Hoffman Propeller blade nut tightening procedure B2.23 which 
requires a certain over-torquing and loosening of the blade nut to 
limit a preload reduction due to material settlement. Prompted by 
this development, Hoffmann Propeller issued SB057 (incorporating 
blade nut tightening procedure B2.23) providing torquing 
instructions, and SB58 providing instructions for setting correct 
counterweight angles. Additionally, Hoffmann Propeller issued the 
torque tightening SB (referencing SB57 and SB58) providing 
inspections and corrective action instructions.
    For the reasons described above, this [EASA] AD retains the 
requirements of EASA AD 2020-0226R1, which is superseded, and 
requires additional blade checks, inspections, and re-tightening of 
the propeller blade nuts.

    You may obtain further information by examining the MCAI in the AD 
docket at www.regulations.gov by searching for and locating Docket No. 
FAA-2022-0980.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed the following service information:
     Hoffmann Propeller Service Bulletin SB057 C, dated 
February 22, 2022. This SB specifies procedures for tightening the 
propeller blade retention nut.
     Hoffmann Propeller Service Bulletin SB059 B, dated 
February 23, 2022. This SB specifies procedures for tightening the 
propeller blade retention nut with the correct torque and inspecting 
the propeller blade for shake.
    This proposed AD would also require Hoffmann Propeller GmbH & Co. 
KG Service Bulletin SB E53 Rev. D, dated February 18, 2021, which was 
previously approved by the Director of the Federal Register for 
incorporation by reference on January 10, 2022 (86 FR 68905, December 
6, 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.

Other Related Service Information

    The FAA reviewed the following service information:
     Hoffmann Propeller Service Bulletin SB058 A, dated 
February 2, 2022. This SB specifies the updated definition of the 
counterweight angle.

Proposed AD Requirements in This NPRM

    This proposed AD would retain all of the requirements of AD 2021-
23-17. This proposed AD would also require a maintenance records review 
and, depending on the results of the maintenance records review, 
tightening of each propeller blade retention nut to specified torque 
values. Depending on the results of the maintenance records review, 
this proposed AD would require initial and repetitive physical 
inspections of the propeller blade for shake. If any axial play is 
detected during inspection, this proposed AD would require the removal 
of the propeller from service and the performance of an NDT inspection 
of the propeller hub.

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:

[[Page 46905]]

                                                 Estimated Costs
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                                                                                     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.
Review maintenance records............  0.5 work-hours x $85 per               0           42.50        1,487.50
                                         hour = $42.50.
----------------------------------------------------------------------------------------------------------------

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

                                               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.
Inspect propeller blade for shake.............  0.25 work-hours x $85 per hour =               0           21.25
                                                 $21.25.
Tighten propeller blade retention nuts........  2 work-hours x $85 per hour =                  0             170
                                                 $170.
----------------------------------------------------------------------------------------------------------------

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 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 2021-23-17, Amendment 39-21815 (86 
FR 68905, December 6, 2021); and
0
b. Adding the following new airworthiness directive:

Hoffmann GmbH & Co. KG: Docket No. FAA-2022-0980; Project Identifier 
MCAI-2022-00448-P.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) action by September 15, 2022.

(b) Affected ADs

    This AD replaces AD 2021-23-17, Amendment 39-21815 (86 FR 68905, 
December 6, 2021) (AD 2021-23-17).

(c) Applicability

    This AD applies to Hoffmann GmbH & Co. KG (Hoffmann) model 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, Amendment 39-21347 (85 FR 78702, 
December 7, 2020)), amend the emergency or abnormal procedures 
section of the existing aircraft flight manual by inserting this 
text: ``Abnormal propeller vibrations: As applicable, reduce engine 
RPM.''
    (2) Before the next flight after January 10, 2022 (the effective 
date of AD 2021-23-17), 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 (Hoffmann 
Propeller SB E53 Rev. D).
    (3) Within 20 flight hours (FHs) after January 10, 2022 (the 
effective date of AD 2021-23-17), perform a non-destructive test 
(NDT) inspection of propeller hub HO-V 72 ( ) ( )-( )-( ) using 
paragraph 2.3 of Hoffmann Propeller SB E53 Rev. D.
    (4) During each overhaul of propeller hub HO-V 72 ( ) ( )-( )-( 
) after January 10, 2022 (the effective date of AD 2021-23-17), 
perform an NDT inspection using paragraph 2.3 of Hoffmann Propeller 
SB E53 Rev. D.
    (5) Within 30 days after the effective date of this AD, review 
the maintenance records

[[Page 46906]]

to confirm the propeller blade retention nuts were tightened at the 
last in-shop maintenance visit to the torque values in paragraph 5 
of Hoffmann Propeller Service Bulletin SB057 C, dated February 22, 
2022 (Hoffmann Propeller SB057 C).
    (6) If, during the records review required by paragraph (g)(5) 
of this AD, it is determined that the propeller blade retention nuts 
were not tightened to the torque values in paragraph 5 of Hoffmann 
Propeller SB057 C, or it cannot be confirmed if the propeller blade 
retention nuts were tightened to the torque values in paragraph 5 of 
Hoffmann Propeller SB057 C, perform the following actions:
    (i) Within 90 FHs after the effective date of this AD, tighten 
each propeller blade retention nut to the torque values in paragraph 
5 of Hoffmann Propeller SB057 C, using paragraphs 6 and 7 of 
Hoffmann Propeller Service Bulletin SB059 B, dated February 23, 
2022.
    (ii) Before the next flight after the effective date of this AD 
and, thereafter, before each flight until the propeller blade 
retention nut is tightened to the torque values in paragraph 5 of 
Hoffmann Propeller SB057 C, as required by paragraph (g)(6)(i) of 
this AD, confirm that there is no axial play in the blade retention 
system by inspecting the propeller blade for shake. If any axial 
play is detected, remove the propeller from service and perform an 
NDT inspection of the propeller hub using paragraph 2.3 of Hoffmann 
Propeller SB E53 Rev. D.
    (7) If, during any inspection required by paragraph (g)(2), (3), 
(4) or (6)(ii) of this AD, any crack is detected, replace propeller 
hub HO-V 72 ( ) ( )-( )-( ) with a part eligible for installation.

(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 Hoffmann Propeller 
SB E53 Rev. D.

(i) Non-Required Actions

    (1) Sending the propeller to Hoffmann for investigation, as 
contained in paragraph 2.1 of Hoffmann Propeller SB E53 Rev. D, is 
not required by this AD.
    (2) Reporting propeller hubs with cracks to Hoffmann, as 
contained in paragraph 2.3 of Hoffmann Propeller SB E53 Rev. D, is 
not required by this AD.

(j) Credit for Previous Actions

    (1) You may take credit for the initial visual inspection and 
NDT inspection of the propeller hub required by paragraphs (g)(2), 
(3), and (4) of this AD if you performed any of these actions before 
January 10, 2022 (the effective date of AD 2021-23-17) 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.
    (2) You may take credit for the records review to confirm the 
propeller blade retention nuts were tightened to the torque values 
as required by paragraph (g)(5) of this AD, and the tightening of 
each propeller blade retention nut as required by paragraph 
(g)(6)(i) of this AD if you performed any of these actions before 
the effective date of this AD during the last in-shop maintenance 
visit using Hoffmann Propeller Service Bulletin SB057 B, dated 
February 8, 2022; Hoffmann Propeller Service Bulletin SB059 A, dated 
February 11, 2022; or Hoffmann Propeller Service Bulletin SB059 B, 
dated February 23, 2022.

(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 paragraph (m)(1) of this AD.
    (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; email: [email protected].
    (2) Refer to European Union Aviation Safety Agency (EASA) AD 
2022-0061, dated April 4, 2022, for more information. You may 
examine the EASA AD in the AD docket at www.regulations.gov by 
searching for and locating it in Docket No. FAA-2022-0980.
    (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 (817) 222-5110.

    Issued on July 22, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-16192 Filed 7-29-22; 8:45 am]
BILLING CODE 4910-13-P