DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-1104; Project Identifier MCAI-2020-01421-P;
Amendment 39-21347; AD 2020-25-05]
Airworthiness Directives; Hoffmann GmbH & Co. KG Propellers
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule; request for comments.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Hoffmann GmbH & Co. KG (Hoffmann) model HO-V 72 propellers. This AD was
prompted by reports of cracks at different positions on two affected
propeller hubs. This AD requires amending the existing aircraft flight
manual (AFM) with abnormal propeller vibration instructions. This AD
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.
This AD 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 this AD, whichever occurs later. The FAA is issuing
this AD to address the unsafe condition on these products.
DATES: This AD is effective December 22, 2020.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of December 22,
The FAA must receive comments on this AD by January 21, 2021.
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
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 final rule, contact
Hoffmann Propeller GmbH & Co. KG, Sales and Service,
Kupferlingstrasse 9, 83022, Rosenheim, Germany; phone: +49 (0)
8031 1878 0; fax: +49 (0) 8031 1878 78; email: firstname.lastname@example.org;
website: 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. It is also available at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-1104.
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-1104; 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, any
comments received, and other information. The street address for the
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:
The European Union Aviation Safety Agency (EASA), which is the
Technical Agent for the Member States of the European Community, has
issued EASA AD 2020-0226-E, dated October 16, 2020 (referred to after
this as ``the MCAI''), to address an unsafe condition for the specified
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 [service bulletin], providing applicable instructions.
For the reasons described above, this [EASA] AD requires
inspections of affected parts and, depending on findings,
replacement, and introduces a life limit for affected parts. This
[EASA] AD also requires, for certain aeroplanes, amendment of the
applicable Aircraft Flight Manual (AFM).
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-2020-1104.
The FAA is issuing this AD because the agency has 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. B, dated October 14, 2020. 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 AD requires amending the existing AFM with abnormal propeller
vibration instructions. This AD 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. This AD 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 this AD, whichever occurs later.
Differences Between the AD and the MCAI
EASA AD 2020-0226-E, dated October 16, 2020, 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 AD
applies to all Hoffmann model HO-V 72 propellers regardless of their
EASA AD 2020-0226-E, dated October 16, 2020, defines the life of
the propeller hub as 30 years since the first installation on the
airplane. This AD defines the life of the propeller hub as 30 years
since the date of manufacture because the installation history of the
propeller might be unknown.
The FAA considers this AD interim action. This unsafe condition is
still under investigation by the manufacturer and, depending on the
results of that investigation, the FAA may consider further rulemaking
Justification for Immediate Adoption and Determination of the Effective
Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5
U.S.C. 551 et seq.) authorizes agencies to dispense with notice and
comment procedures for rules when the agency, for ``good cause,'' finds
that those procedures are ``impracticable, unnecessary, or contrary to
the public interest.'' Under this section, an agency, upon finding good
cause, may issue a final rule without providing notice and seeking
comment prior to issuance. Further, section 553(d) of the APA
authorizes agencies to make rules effective in less than thirty days,
upon a finding of good cause.
An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies foregoing notice and comment prior to adoption of this rule.
During a scheduled inspection, a crack was found by an operator on a
propeller hub. A second crack was found on another propeller hub during
an unscheduled inspection by an operator after abnormal vibrations
occurred in-flight. Hoffmann Propeller immediately issued service
information instructing operators to visually inspect the hub for
cracks before the next flight while the cause of the cracks are under
A crack in the propeller hub can result in the loss of a propeller
blade, resulting in an imbalance in the entire engine which can render
the aircraft uncontrollable. The FAA considers a crack in the propeller
hub an urgent safety issue that requires an immediate action to avoid
potential loss of the airplane. Accordingly, notice and opportunity for
prior public comment are impracticable and contrary to the public
interest pursuant to 5 U.S.C. 553(b)(3)(B). In addition, the FAA finds
that good cause exists pursuant to 5 U.S.C. 553(d) for making this
amendment effective in less than 30 days, for the same reasons the FAA
found good cause to forego notice and comment.
The FAA invites you to send any written data, views, or arguments
about this final rule. Send your comments to an address listed under
ADDRESSES. Include the docket number FAA-2020-1104 and Project
Identifier MCAI-2020-01421-P at the beginning of your comments. The
most helpful comments reference a specific portion of the final rule,
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 this final rule 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 received about this final rule.
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 AD 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 AD, 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 AD. 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.
Regulatory Flexibility Act
The requirements of the Regulatory Flexibility Act (RFA) do not
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt
a rule without prior notice and comment. Because FAA has determined
that it has good cause to adopt this rule without prior notice and
comment, RFA analysis is not required.
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:
||1 work-hour x $85 per hour =
|Visually inspect propeller hub
||1 work-hour x $85 per hour=
|NDT inspect propeller hub
||8 work-hours x $85 per hour=
The FAA estimates the following costs
to do any necessary
replacement that would be required based on the results of the
inspections. The agency has no way of determining the number of
aircraft that might need this replacement:
|Replace propeller hub
||5 work-hours x $85 per hour =
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.
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, and
(2) Will not affect intrastate aviation in Alaska.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
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