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PROPOSED AD WILLIAMS INTERNATIONAL CO., L.L.C.: Docket No. FAA-2021-0511; Project Identifier AD-2020-01229-E.
(a) COMMENTS DUE DATE

    The FAA must receive comments on this  airworthiness directive (AD) by
    August 9, 2021.

(b) AFFECTED ADS

    None.

(c) APPLICABILITY

    This AD applies to Williams International Co., L.L.C. (Williams) FJ44-
    2A, FJ44-2C, FJ44-3A,  and FJ44-3A-24  model  turbofan  engines with a
    serial number identified in  paragraph 1.A., Effectivity, of  Williams
    International Service Bulletin WISB-72-1032, dated March 23, 2020 (the
    SB), with an installed  high-pressure turbine (HPT) disk,  part number
    (P/N) 67093.

(d) SUBJECT

    Joint Aircraft System Component (JASC) Code 7250, Turbine Section.

(e) UNSAFE CONDITION

    This AD was prompted by a report  of cracks in the HPT disk posts  and
    failure of an HPT disk post, resulting in the release of an HPT blade.
    The FAA is issuing this AD to prevent cracking and failure of the  HPT
    disk posts. The  unsafe condition, if  not addressed, could  result in
    uncontained release of the HPT blade, damage to the engine, and damage
    to the airplane.

(f) COMPLIANCE

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

(g) REQUIRED ACTIONS

(1) For FJ44-2A and FJ44-2C model turbofan engines, within the  compliance
    times specified in  Table 1 to  paragraph (g) of  this AD, remove  the
    affected HPT disk from service and replace it with a part eligible for
    installation   using   paragraphs   2.C.   and   E.,    Accomplishment
    Instructions--FJ44-2A & FJ44-2C, of the SB.

(2) For FJ44-3A and  FJ44-3A-24  model turbofan  engines, within  the com-
    pliance times specified in Table 1 to paragraph (g) of this AD, remove
    the affected HPT disk from service and replace it with a part eligible
    for installation using paragraphs 3.C. and D., of the SB.
    ______________________________________________________________________

            TABLE 1 TO PARAGRAPH (G) - COMPLIANCE TIME                    
    ______________________________________________________________________

    HPT DISK, P/N 67093, CYCLES     REPLACE WITHIN HPT DISK
    SINCE NEW (CSN) AS OF THE       CYCLES
    EFFECTIVE DATE OF THIS AD

    Less than 1,000 CSN             1,620 CSN
    1,000 to 2,000 CSN              2,530 CSN
    2,001 to 3,000 CSN              3,245 CSN
    3,001 to 4,000 CSN              4,130 CSN
    4,001 or higher CSN             130 cycles after the effective date of
                                    this AD
    ______________________________________________________________________

(h) DEFINITION

    For the purpose of this AD, a part eligible for installation is an HPT
    disk with a P/N other than P/N 67093.

(i) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS)

(1) The Manager, Chicago ACO, 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.

(j) RELATED INFORMATION

(1) For more information about this AD, contact Kyle Bush, Aviation Safety
    Engineer,  Chicago  ACO  Branch,  FAA,  2300  East  Devon  Avenue, Des
    Plaines, IL 60018; phone: (847) 294-7870; fax: (847) 294-7834;  email:
    kyle.bush@faa.gov.

(2) For service information identified in this AD, contact Williams Inter-
    national Co., L.L.C., Product Support, 2000 Centerpoint Pkwy, Pontiac,
    MI  48341;   phone:  (800)   859-3544;  website:   http://www.williams
    -int.com/product-support.  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 J une 21, 2021. Lance T.  Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

DATES: The  FAA must  receive comments  on this  proposed AD  by August 9,
2021.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


14 CFR Part 39

[Docket No. FAA-2021-0511; Project Identifier AD-2020-01229-E]
RIN 2120-AA64

Airworthiness Directives; Williams International Co., L.L.C.
Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Williams International Co., L.L.C. (Williams) FJ44-2A,
FJ44-2C, FJ44-3A, and FJ44-3A-24 model turbofan engines. This proposed
AD was prompted by a report of cracks in high-pressure turbine (HPT)
disk posts and failure of an HPT disk post. This proposed AD would
require the removal and replacement of the affected HPT disk before
reaching its new life limit. 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 9, 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 Williams
International Co., L.L.C., Product Support, 2000 Centerpoint Pkwy.,
Pontiac, MI 48341; phone: (800) 859-3544; website:
http://www.williams-int.com/product-support. You may view
this service information at the Chicago ACO Branch, 2300 East Devon
Avenue, Des Plaines, IL 60018. 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-2021-0511; 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, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Kyle Bush, Aviation Safety Engineer,
Chicago ACO Branch, FAA, 2300 East Devon Avenue, Des Plaines, IL 60018;
phone: (847) 294-7870; fax: (847) 294-7834; email: kyle.bush@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-2021-0511; Project Identifier
AD-2020-01229-E" 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
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
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 NPRM.

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 Kyle
Bush, Aviation Safety Engineer, Chicago ACO Branch, FAA, 2300 East
Devon Avenue, Des Plaines, IL 60018. 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 received a report that Williams discovered cracks in one
HPT disk post during a scheduled inspection of an FJ44-2A model
turbofan engine. An operator also discovered that one HPT disk post
failed, while the engine was in service, resulting in the release of an
HPT blade.

Williams initiated an investigation to understand the root cause of
the cracks and to determine the necessary corrective action. Williams
found that, between August 2018 and July 2019, nine FJ44-2A HPT disks
were rejected during inspection after discovery of cracks in the HPT
disk post. As part of its investigation, Williams conducted several
tests and analysis to determine the failure mechanism. Engine tests
confirmed that FJ44-2A and FJ44-2C model turbofan engines operate at a
higher temperature than most recently certified engines. Metallurgical
evaluation showed cracking is inter-granular with oxidation attack near
and around the crack, with no fatigue striations. Metallurgical
evaluation and comparison of HPT disk, part number (P/N) 67093,
installed on both FJ44-2A and FJ44-3A model turbofan engines, showed
cracking of the HPT disk.

As a result of this investigation, Williams determined the root
cause of this cracking was due to higher temperatures and a difference
in manufacturing processes (electrical discharge machining vs.
broaching). Williams determined that these cracks have only occurred on
HPT disks with P/N 67093. Williams subsequently issued service
information to instruct operators to remove the HPT disk, P/N 67093.
This condition, if not addressed, could result in failure of the
engine, in-flight shutdown of the engine, and loss of control of the
aircraft.

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 Williams International Service Bulletin (SB) WISB-
72-1032, dated March 23, 2020. This service information specifies
procedures for removing and replacing the HPT rotor assemblies that
include HPT disk, P/N 67093. The service information also provides
instructions for incorporating the latest HPT combustor/fuel slinger
module on FJ44-2A and FJ44-2C model turbofan engines. 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 Williams International SB WISB-72-1034, Revision
1, dated June 10, 2020. Williams International SB WISB-72-1034
describes procedures for re-identifying the HPT rotor assembly and HPT disk.

Proposed AD Requirements in This NPRM


This proposed AD would require removing the HPT disk, P/N 67093,
from service before reaching its new life limit and replacing it with a
part eligible for installation.

Differences Between This Proposed AD and the Service Information


The Accomplishment Instructions, paragraph 2.D., of Williams
International SB WISB-72-1032, dated March 23, 2020, instruct operators
of FJ44-2A and FJ44-2C model turbofan engines to replace or rework the
HPT combustor/fuel slinger module on FJ44-2A and FJ44-2C model turbofan
engines, while this proposed AD does not. Replacement or rework of the
HPT combustor/fuel slinger module is not necessary to resolve the
unsafe condition in this proposed AD and is therefore not proposed by
this AD.

The Accomplishment Instructions, paragraphs 2.C. and E. and 3.C.
and D., of Williams International SB WISB-72-1032, dated March 23,
2020, specify procedures for removing and replacing the HP turbine
rotor assembly containing HPT disk, P/N 67093, whereas this proposed AD
mandates removing and replacing the HPT disk, P/N 67093. Although
removing the HPT rotor assembly is a necessary step in the replacement
of the HPT disk, this proposed AD only requires replacement of the HPT
disk to resolve the unsafe condition addressed by this proposed AD.

Costs of Compliance


The FAA estimates that this AD, if adopted as proposed, would
affect 213 engines installed on 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
Remove and replace the HPT disk 33 work-hours x $85 per hour = $2,805.
$16,694
$19,499
$4,153,287

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.

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: