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PROPOSED AD LEARJET, INC.: Docket No. FAA-2022-0991; Project Identifier AD-2022-00155-T.
(a) COMMENTS DUE DATE

    The FAA must receive comments on this airworthiness directive (AD)  by
    December 27, 2022.

(b) AFFECTED ADS

    This AD affects AD 2001-03-05, Amendment 39-12109 (66 FR 10353, Febru-
    ary 15, 2001) (AD 2001-03-05).

(c) APPLICABILITY

    This AD applies to Learjet, Inc, Model 45 (Learjet 40), Model 45 (Lear
    jet 45),  Model 45 (Learjet 70),  and Model 45 (Learjet 75) airplanes,
    certificated in any category,  with an original airworthiness certifi-
    cate or original export certificate of airworthiness  issued on or be-
    fore January 18, 2022.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 36, Pneumatic.

(e) UNSAFE CONDITION

    This AD was prompted by  a determination that new or  more restrictive
    airworthiness limitations are necessary. The FAA is issuing this AD to
    address metal  fragments breaking  off the  anti-ice manifold assembly
    due to fatigue, which  could block a duct  in the anti-ice system  and
    result in an unannunciated loss of ice protection and subsequent  loss
    of control of the airplane.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) MAINTENANCE OR INSPECTION PROGRAM REVISION

(1) For Learjet 40 and 45 variants:  Within 60 days  after  the  effective
    date of this AD, revise the existing inspection program by incorporat-
    ing the information  in Learjet 40 Maintenance Manual  Temporary Revi-
    sion (TR) 04-33 or Learjet 45 Maintenance Manual TR 04-48,  both dated
    January 18, 2022,  as applicable.  The initial compliance time for the
    inspection is at the applicable time  specified in paragraph (g)(1)(i)
    or (ii) of this AD.

(i) For airplanes  with  more  than 600 flight hours since the most recent
    inspection of the anti-ice manifold  assembly was performed as of  the
    effective date of this AD:  Do the inspection within 100  flight hours
    or  60 days  after the  effective date  of this  AD, whichever  occurs
    first.

(ii) For airplanes with 600 flight hours or less since the most recent in-
     spection of the  anti-ice manifold assembly  was performed as  of the
     effective date of this AD: Do the inspection within 600 flight  hours
     after the most recent inspection or within 100 flight hours after the
     effective date of this AD, whichever occurs later.

(2) For Learjet 70 and 75 variants:  Within 60 days  after  the  effective
    date of this AD, revise the existing inspection program to incorporate
    the information identified in figure 1 to paragraph (g)(2) of this AD.
    The initial compliance  time for the  inspection is at  the applicable
    time specified in paragraph (g)(2)(i) or (ii) of this AD.

           FIGURE 1 TO PARAGRAPH (G)(2) – ANTI-ICE INSPECTION TASKS       
    ______________________________________________________________________
    IRN
    NUMBER    TASK DESCRIPTION   TASK INTERVAL   MODEL/SERIAL EFFECTIVITY
    ______________________________________________________________________
    3010006   **Anti-ice           600 flight    Learjet 70/75: 45-0368,
              Manifold -           hours (T)     45-0446 45-0456 through
              Perform Borescope                  45-2000, 45-2129, 45-2134
              Inspection                         through 45-4000
    ______________________________________________________________________

(i) For airplanes  with  more  than 600 flight hours since the most recent
    inspection of the anti-ice manifold  assembly was performed as of  the
    effective date of this AD:  Do the inspection within 100  flight hours
    or  60 days  after the  effective date  of this  AD, whichever  occurs
    first.

(ii) For airplanes with 600 flight hours or less since the most recent in-
     spection of the  anti-ice manifold assembly  was performed as  of the
     effective date of this AD: Do the inspection within 600 flight  hours
     after the most recent inspection or within 100 flight hours after the
     effective date of this AD, whichever occurs later.

(h) NO ALTERNATIVE ACTIONS OR INTERVALS

    After the existing inspection program  has been revised as required by
    paragraph (g) of this  AD, no alternative actions  (e.g., inspections)
    or  intervals,  may  be  used unless  the  actions  and  intervals are
    approved as an alternative  method of compliance (AMOC)  in accordance
    with the procedures specified in paragraph (k) of this AD.

(i) TERMINATING ACTION FOR PARAGRAPH (C) OF AD 2001-03-05

    Accomplishing the revision of the existing inspection program required
    by paragraph (g) of this AD terminates  the requirements  of paragraph
    (c) of AD 2001-03-05.

(j) SPECIAL FLIGHT PERMIT

    Special flight permits  may be issued in accordance with 14 CFR 21.197
    and 21.199 to operate the airplane  to  a  location where the airplane
    can be inspected, provided the airplane is restricted from flying into
    known icing conditions.

(k) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The  Manager,  Wichita 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  responsible  Flight  Standards  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 (l) of this AD.

(2) Before using any approved AMOC,  notify your appropriate principal in-
    spector, or lacking a principal inspector,  the manager of the respon-
    sible Flight Standards Office.

(l) RELATED INFORMATION

    For more information about this AD,  contact Adam Hein, Aerospace Eng-
    ineer,  Mechanical Systems and Propulsion Section,  FAA,  Wichita  ACO
    Branch, 1801 S Airport Road,  Wichita, KS 67209;  telephone (316) 946-
    4116; email: adam.hein@faa.gov.

(m) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference (IBR) of the service information  listed  in  this paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable  to do the actions
    required by this AD, unless the AD specifies otherwise.

(i) Learjet 40 Maintenance Manual Temporary Revision 04-33,  dated January
    18, 2022.

(ii) Learjet 45 Maintenance Manual Temporary Revision 04-48, dated January
     18, 2022.

(3) For service information identified in this AD,  contact Learjet, Inc.,
    One Learjet Way, Wichita, KS 67209-2942;  telephone 316-946-2000;  fax
    316-946-2220; email ac.ict@aero.bombardier.com; website bombardier.com

(4) You may view this service information at the FAA,  Airworthiness Prod-
    ucts 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.

(5) You may view  this service information  that is incorporated by refer-
    ence at the National Archives and Records Administration  (NARA).  For
    information on the availability of this material at NARA fr.inspection
    @nara.gov or go to www.archives.gov/federal-register/cfr/ibr-locations
    .html.

Issued on November 1, 2022.  Christina Underwood, Acting Director, Compli-
ance & Airworthiness Division, Aircraft Certification Service.

DATES: The comment period  for the NPRM  published in the Federal Register
on August 11, 2022 (87 FR 49556),  is reopened.  The FAA must receive com-
ments on this SNPRM by December 27, 2022.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0991; Project Identifier AD-2022-00155-T]
RIN 2120-AA64

Airworthiness Directives; Learjet, Inc., Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM).

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

SUMMARY: The FAA is revising a notice of proposed rulemaking (NPRM)
that applied to certain Learjet, Inc., Model 45 airplanes. This action
revises the NPRM by adding airplanes to the applicability. The FAA is
proposing this airworthiness directive (AD) to address the unsafe
condition on these products. Since these actions would impose an
additional burden over that in the NPRM, the FAA is requesting comments
on this SNPRM.

DATES: The comment period for the NPRM published in the Federal
Register on August 11, 2022 (87 FR 49556), is reopened.
The FAA must receive comments on this SNPRM by December 27, 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 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.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-0991; 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 SNPRM, any comments received, and other
information. The street address for Docket Operations is listed above.
Material Incorporated by Reference:
For service information identified in this SNPRM, contact
Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 316-
946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; website
bombardier.com.
You may view this service information at the FAA,
Airworthiness Products 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.

FOR FURTHER INFORMATION CONTACT: Adam Hein, Aerospace Engineer,
Mechanical Systems and Propulsion Section, FAA, Wichita ACO Branch,
1801 S Airport Road, Wichita, KS 67209; telephone (316) 946-4116;
email: adam.hein@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-2022-0991; Project Identifier
AD-2022-00155-T'' 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 again
revise this 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
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received 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 SNPRM 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 SNPRM, 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 SNPRM. Submissions containing CBI should
be sent to Adam Hein, Aerospace Engineer, Mechanical Systems and
Propulsion Section, FAA, Wichita ACO Branch, 1801 S Airport Road,
Wichita, KS 67209; telephone (316) 946-4116; email: adam.hein@faa.gov.
Any commentary that the FAA receives that is not specifically
designated as CBI will be placed in the public docket for this
rulemaking.

Background

The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that
would apply to certain Learjet, Inc., Model 45 airplanes airplanes. The
NPRM published in the Federal Register on August 11, 2022 (87 FR
49556). The NPRM was prompted by a determination that new or more
restrictive airworthiness limitations are necessary. In the NPRM, the
FAA proposed to require revising the existing inspection program to
incorporate reduced inspection intervals for the anti-ice manifold
assembly.

Related Rulemaking

The FAA issued AD 2001-03-05, Amendment 39-12109 (66 FR 10353,
February 15, 2001) (AD 2001-03-05), for certain Learjet Model 45
airplanes. AD 2001-03-05 requires, among other actions, revising the
existing Learjet 45 maintenance program to incorporate additional
inspections and maintenance practices for the anti-ice manifold
assembly, including a 600-hour repetitive inspection interval of an
earlier design/part number of the anti-ice manifold. Since the FAA
issued AD 2001-03-05, the anti-ice manifold was redesigned and the inspection
interval was extended to 1,200 flight hours. The design approval holder
subsequently determined that the design improvements made to the anti-
ice manifold assembly did not fully address the original issue of vane
cracking, so the 1,200-hour inspection on the redesigned part is
insufficient. However, the FAA determined that a repetitive inspection
interval of 600 flight hours is sufficient to address the unsafe
condition. Therefore, this proposed AD would require revising the
existing inspection program to incorporate a reduced 600-hour
inspection interval for the redesigned part. Accomplishing the required
actions in this proposed AD would terminate the requirements of
paragraph (c) of AD 2001-03-05.

Actions Since the NPRM Was Issued

Since the FAA issued the NPRM, the FAA determined that the list of
affected serial numbers specified in paragraph (c) of the proposed AD
was incomplete. The FAA has determined that this proposed AD should
apply to airplanes with an original airworthiness certificate or
original export certificate of airworthiness issued on or before
January 18, 2022. Airplanes with an original airworthiness certificate
or original export certificate of airworthiness issued after January
18, 2022 must comply with the airworthiness limitations specified as
part of the approved type design and referenced on the type certificate
data sheet; this proposed AD therefore does not include those airplanes
in the applicability.

Comments

The FAA received no comments on the NPRM or on the determination of
the cost to the public.

FAA's Determination

The FAA is proposing this AD after determining the unsafe condition
described previously is likely to exist or develop in other products of
the same type design. Certain changes described above expand the scope
of the NPRM. As a result, it is necessary to reopen the comment period
to provide additional opportunity for the public to comment on this
SNPRM.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Learjet 40 Maintenance Manual Temporary Revision
(TR) 04-33 and Learjet 45 Maintenance Manual TR 04-48, both dated
January 18, 2022. This service information specifies reduced inspection
intervals for the anti-ice manifold assembly. These documents are
distinct since they apply to different airplane configurations. 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 SNPRM

This proposed AD would require revising the existing inspection
program to incorporate reduced inspection intervals for the anti-ice
manifold assembly.
This proposed AD would require revisions to certain operator
maintenance documents to include new actions (e.g., inspections).
Compliance with these actions is required by 14 CFR 91.403(c). For
airplanes that have been previously modified, altered, or repaired in
the areas addressed by this proposed AD, the operator may not be able
to accomplish the actions described in the revisions. In this
situation, to comply with 14 CFR 91.403(c), the operator must request
approval for an alternative method of compliance according to paragraph
(k) of this proposed AD.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 481 airplanes of U.S. registry. The FAA estimates the following
costs to comply with this proposed AD:

Estimated Costs

Action
Labor cost
Parts cost
Cost per product
Cost on U.S. operators
Inspection program revision 1 work-hour x $85 per hour = $85
$0
$85
$40,885

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 this 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:

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
directive: