[Federal Register Volume 86, Number 120 (Friday, June 25, 2021)]
[Proposed Rules]
[Pages 33579-33581]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-13516]


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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).

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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: [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-2021-0511; 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.

[[Page 33580]]

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
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Remove and replace the HPT disk.......  33 work-hours x $85 per          $16,694         $19,499      $4,153,287
                                         hour = $2,805.
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    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

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 adding the following new airworthiness 
directive:

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.

[[Page 33581]]

(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 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 3.C. and D., of the 
SB.
[GRAPHIC] [TIFF OMITTED] TP25JN21.009

(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: [email protected].
    (2) For service information identified in this AD, 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 
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 21, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-13516 Filed 6-24-21; 8:45 am]
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