[Federal Register Volume 86, Number 105 (Thursday, June 3, 2021)]
[Proposed Rules]
[Pages 29707-29709]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11565]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0447; Project Identifier AD-2021-00131-E]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney 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 all Pratt & Whitney (PW) PW1500G and PW1900G series turbofan 
engines. This proposed AD was prompted by reports of cracks in the 
high-pressure compressor (HPC) rotor shaft that resulted in in-flight 
shutdowns (IFSDs) and unscheduled engine removals (UERs). This proposed 
AD would require removal and replacement of the HPC front hub and HPC 
rotor shaft. 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 July 19, 
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 Pratt & 
Whitney, 400 Main Street, East Hartford, CT 06118; phone: (800) 565-
0140; fax: (860) 565-5442; email: [email protected]; website: https://fleetcare.pw.utc.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.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No.

[[Page 29708]]

FAA-2021-0447; 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: Mark Taylor, Aviation Safety Engineer, 
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 
(781) 238-7229; fax: (781) 238-7199; 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-2021-0447; Project Identifier 
AD-2021-00131-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 Mark 
Taylor, Aviation Safety Engineer, ECO 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 received reports of cracks in the HPC rotor shaft that 
resulted in vibration and subsequent IFSDs and UERs. The manufacturer 
determined that the threads on the HPC rotor shaft were not optimized 
for load distribution, which resulted in vibration stresses. During one 
occurrence, oil was released at the high-pressure turbine (HPT) disk 
bore location. The manufacturer redesigned the HPC front hub and HPC 
rotor shaft for increased durability and decreased vibration stress. 
The redesigned HPC front hub is made from nickel to help with corrosion 
resistance. The threads on the HPC rotor shaft were also redesigned to 
help distribute the load on the threads and decrease vibration stress. 
This condition, if not addressed, could result in release of an HPT 
disk, damage to the engine, and damage to the airplane.

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

    The FAA reviewed Pratt & Whitney Service Bulletin (SB) PW1000G-A-
72-00-0154-00A-930A-D, Issue No. 001, dated May 7, 2021 (PW1000G-A-72-
00-0154-00A-930A-D), and Pratt & Whitney SB PW1000G-A-72-00-0101-00B-
930A-D, Issue No. 001, dated May 7, 2021 (SB PW1000G-A-72-00-0101-00B-
930A-D). These SBs describe procedures for removing and replacing the 
HPC front hub and HPC rotor shaft.

Proposed AD Requirements in This NPRM

    This proposed AD would require removal and replacement of the HPC 
front hub and HPC rotor shaft.

Differences Between This Proposed AD and the Service Information

    Pratt & Whitney SB PW1000G-A-72-00-0154-00A-930A-D and Pratt & 
Whitney SB PW1000G-A-72-00-0101-00B-930A-D provide instructions to 
concurrently perform the actions in Pratt & Whitney SB PW1000G-A-72-00-
0157-00A-930A-D and SB PW1000G-A-72-00-0105-00B-930A-D, respectively. 
This AD does not require performance of the actions described in Pratt 
& Whitney SB PW1000G-A-72-00-0157-00A-930A-D or SB PW1000G-A-72-00-
0105-00B-930A-D since these SBs describe ring seal replacement, which 
is not related to the unsafe condition addressed by this AD.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 94 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
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Replace HPC front hub and HPC rotor   25.75 work-hours x $85         $120,090     $122,278.75     $11,494,202.50
 shaft.                                per hour = $2,188.75.
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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.

[[Page 29709]]

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:

Pratt & Whitney: Docket No. FAA-2021-0447; Project Identifier AD-
2021-00131-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by July 19, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Pratt & Whitney PW1519G, PW1521G, PW1521G-3, 
PW1521GA, PW1524G, PW1524G-3, PW1525G, PW1525G-3, PW1919G, PW1921G, 
PW1922G, PW1923G, and PW1923G-A model turbofan engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section.

(e) Unsafe Condition

    This AD was prompted by reports of cracks in the high-pressure 
compressor (HPC) rotor shaft that resulted in in-flight shutdowns 
and unscheduled engine removals. The FAA is issuing this AD to 
prevent cracking of the HPC rotor shaft. The unsafe condition, if 
not addressed, could result in release of a high-pressure turbine 
disk, 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 Action

    At next engine shop visit after the effective date of this AD, 
remove HPC front hub, part number (P/N) 30G1910 or 30G3210, and HPC 
rotor shaft, P/N 30G1854, 30G3109, 30G4995, 30G4953, or 31G0014, 
from service and replace each part with a part eligible for 
installation.

(h) Definitions

    (1) For the purpose of this AD, an ``engine shop visit'' is the 
induction of an engine into the shop for maintenance involving the 
separation of pairs of major mating engine case flanges, except for 
the following, which do not constitute an engine shop visit:
    (i) Separation of engine flanges solely for the purposes of 
transportation without subsequent maintenance does not constitute an 
engine shop visit.
    (ii) Separation of engine flanges solely for the purpose of 
replacing the fan without subsequent maintenance does not constitute 
an engine shop visit.
    (2) For the purpose of this AD, a ``part eligible for 
installation'' is:
    (i) For a HPC front hub: Any HPC front hub with a P/N other than 
P/N 30G1910 or 30G3210; and
    (ii) For a HPC rotor shaft: Any HPC rotor shaft with a P/N other 
than P/N 30G1854, 30G3109, 30G4995, 30G4953, or 31G0014.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, ECO 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 Related Information. You may email your request to: 
[email protected].
    (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

    For more information about this AD, contact Mark Taylor, 
Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: (781) 238-7229; fax: (781) 238-7199; 
email: [email protected].

    Issued on May 27, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-11565 Filed 6-2-21; 8:45 am]
BILLING CODE 4910-13-P