
[Federal Register Volume 88, Number 151 (Tuesday, August 8, 2023)]
[Proposed Rules]
[Pages 53406-53409]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-16722]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-1638; Project Identifier AD-2022-00466-E]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Division Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2018-02-10, which applies to certain Pratt & Whitney Division (PW) 
Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 
engines. AD 2018-02-10 requires performing repetitive fluorescent 
penetrant inspections (FPIs) to detect cracks in the outer diffuser 
case (ODC), removal of any ODC that fails inspection, and requires 
updating the mandatory inspections in the Airworthiness Limitations 
Section (ALS) of the Instructions for Continued Airworthiness (ICA). 
Since the FAA issued AD 2018-02-10, PW developed a modification to 
reduce the susceptibility of ODC cracking. This proposed AD would 
retain the ALS update requirement from AD 2018-02-10, would require 
replacing certain ODC part numbers with parts eligible for 
installation, would expand the applicability to all ODC part numbers, 
and would adjust the compliance threshold of the FPIs of the ODC. 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 September 
22, 2023.

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 by 
searching for and locating Docket No. FAA-2023-1638; 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.
    Material Incorporated by Reference:
     For service information identified in this NPRM, contact 
Pratt & Whitney Division, 400 Main Street, East Hartford, CT 06118; 
phone: (860) 565-0140; email: [email protected]; website: 
connect.prattwhitney.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 (817) 222-5110.

FOR FURTHER INFORMATION CONTACT: Carol Nguyen, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
(781) 238-7655; 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-2023-1638; Project Identifier 
AD-2022-00466-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 
the 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 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 Carol 
Nguyen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des 
Moines, WA 98198. 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 issued AD 2018-02-10, Amendment 39-19163 (83 FR 2896, 
January 22, 2018), (AD 2018-02-10), for PW Model PW4074, PW4074D, 
PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines with ODC part 
number (P/N) 50J775 or P/N 50J930, installed. AD 2018-02-10 was 
prompted by the discovery of multiple cracked ODCs. AD 2018-02-10 
requires initial and repetitive FPIs of the ODC to detect cracks, and 
depending on the results of the FPI, replacement of any ODC that fails 
inspection. Also, AD 2018-02-10 requires updating the

[[Page 53407]]

mandatory inspections in the ALS of the ICA to include piece-part 
inspections. The agency issued AD 2018-02-10 to prevent failure of the 
ODC.

Actions Since AD 2018-02-10 Was Issued

    Since the FAA issued AD 2018-02-10, PW determined that cracks on 
the ODC originated due to high stress in the area between Tt3 boss and 
thermocouple bracket boss. PW developed a modification to improve the 
surface area between Tt3 boss and thermocouple bracket boss to reduce 
the ODC's susceptibility to cracking.
    Consequently, the FAA determined that it is necessary to expand the 
applicability to all ODC P/Ns, adjust the initial FPI threshold for the 
ODC to improve the inspection program, and to require certain ODCs to 
be replaced with an ODC that has been modified to lower the stresses in 
the area between Tt3 boss and thermocouple bracket boss. This 
condition, if not addressed, could result in failure of the ODC, 
uncontained ODC release, 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 Under 1 CFR Part 51

    The FAA reviewed PW Alert Service Bulletin (ASB) PW4G-112-A72-347, 
Revision 4, dated September 1, 2022. This ASB provides guidance on 
performing FPIs on certain bosses of the ODC. 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 PW Service Bulletin (SB) PW4G-112-72-357, dated 
February 25, 2019. This SB provides procedures to modify and re-
identify ODC assemblies to lower the stresses in the area between the 
Tt3 boss and the thermocouple bracket boss.

Proposed AD Requirements in This NPRM

    This proposed AD would retain certain requirements of AD 2018-02-
10. This proposed AD would require revising the ALS of the existing 
airplane maintenance manual or ICA and your existing approved 
maintenance program, as applicable, to include piece-part inspections 
of the ODC, would expand the applicability to include all engines, 
would require initial and repetitive FPIs, and depending on the results 
of the FPI, would require removal or re-inspection of the ODC. This 
proposed AD would also require replacement of certain ODCs with a part 
eligible for installation at next piece-part exposure.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 108 engines installed on airplanes of U.S. registry. The FAA has 
no way to determine the number of operators that will replace the ODC 
with a modified ODC or a zero-time ODC. As a result, the total cost on 
U.S. operators for these actions is not estimated.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Perform high sensitivity FPI of the     10 work-hours x $85 per               $0            $850         $91,800
 ODC T3 thermocouple probe boss.         hour = $850.
Revise the ALS........................  1 work-hour x $85 per                  0              85           9,180
                                         hour = $85.
Replacement of ODC with modified ODC..  3 work-hours x $85 per            12,000          12,255  ..............
                                         hour = $255.
Replacement of ODC with zero-time ODC.  3 work-hours x $85 per         2,300,000       2,300,255  ..............
                                         hour = $255.
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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.

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 that the 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:

[[Page 53408]]

0
a. Removing Airworthiness Directive 2018-02-10, Amendment 39-19163 (83 
FR 2896, January 22, 2018); and
0
b. Adding the following new airworthiness directive:

Pratt & Whitney Division: Docket No. FAA-2023-1638; Project 
Identifier AD-2022-00466-E.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) action by September 22, 2023.

(b) Affected ADs

    This AD replaces AD 2018-02-10, Amendment 39-19163 (83 FR 2896, 
January 22, 2018).

(c) Applicability

    This AD applies to Pratt & Whitney Division (PW) Model PW4074, 
PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7240, Turbine Engine 
Combustion Section.

(e) Unsafe Condition

    This AD was prompted by the discovery of multiple cracked outer 
diffuser cases (ODCs). We are issuing this AD to prevent failure of 
the ODC. This condition, if not addressed, could result in failure 
of the ODC, 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) Within the compliance times specified in paragraphs 
(g)(1)(i) though (iii) of this AD, perform an initial high 
sensitivity fluorescent penetrant inspection (FPI) of the ODC T3 
thermocouple probe boss (Tt3 boss) for crack indications in 
accordance with the Accomplishment Instructions, paragraph 1.F. of 
Part A or paragraph 1.B. of Part B, as applicable, of PW Alert 
Service Bulletin PW4G-112-A72-347, Revision 4, dated September 1, 
2022 (ASB PW4G-112-A72-347, Rev 4).
    (i) For an ODC that has accumulated less than 12,000 cycles 
since new (CSN) with no prior high sensitivity FPI of the ODC Tt3 
boss, perform the high sensitivity FPI before accumulating 9,200 CSN 
or within 1,000 flight cycles (FCs), after the effective date of 
this AD, whichever occurs later.
    (ii) For an ODC with unknown CSN or an ODC that has accumulated 
12,000 CSN or more with no prior high sensitivity FPI of the ODC Tt3 
boss, perform the high sensitivity FPI before accumulating 13,000 
CSN or within 1,000 FCs, after February 26, 2018 (the effective date 
of AD 2018-02-10), whichever occurs later.
    (iii) For an ODC that has undergone a high sensitivity FPI of 
the ODC Tt3 boss prior to the effective date of this AD that 
resulted in no crack indication, perform the high sensitivity FPI 
before accumulating 2,000 FCs since performance of the last FPI or 
during the next engine shop visit, whichever occurs first.
    (iv) For an ODC that has undergone a high sensitivity FPI of the 
ODC Tt3 boss prior to the effective date of this AD that resulted in 
an indication of a crack, perform the actions required by paragraphs 
(g)(3)(i) through (iii) of this AD, as applicable.
    (2) Thereafter, repeat the high sensitivity FPI of the ODC Tt3 
boss at each engine shop visit or before exceeding 2,000 FCs from 
the last high sensitivity FPI of the ODC Tt3 boss, whichever occurs 
first, in accordance with the Accomplishment Instructions, 
paragraphs 1.F. of Part A or paragraph 1.B. of Part B, as 
applicable, of ASB PW4G-112-A72-347, Rev 4.
    (3) If, during any inspection required by paragraphs (g)(1) or 
(2) of this AD, there is any crack indication, perform the actions 
specified in paragraphs (g)(3)(i) through (iii) of this AD.
    (i) For engines installed on an aircraft, repeat the high 
sensitivity FPI or remove the ODC from service in accordance with 
the actions and compliance times specified in the Accomplishment 
Instructions, Part A, paragraphs 1.G. and 1.H., of ASB PW4G-112-A72-
347, Rev 4.
    (ii) For engines not installed on an aircraft, repeat the high 
sensitivity FPI or remove the ODC from service in accordance with 
the actions and compliance times specified in the Accomplishment 
Instructions, Part B, paragraphs 1.C. and 1.D., of PW ASB PW4G-112-
A72-347, Rev 4.
    (iii) For engines at an engine shop visit, before further 
flight, remove the ODC from service.
    (4) Within 30 days after the effective date of this AD, revise 
the Airworthiness Limitations Section (ALS) of the existing engine 
maintenance manual or Instructions for Continued Airworthiness and 
the existing approved maintenance program, as applicable, to include 
the piece-part inspections of the ODC as defined in Table 1 to 
paragraph (g)(4) of this AD.

                                  Table 1 to Paragraph (g)(4)--Addition to ALS
----------------------------------------------------------------------------------------------------------------
                                                   Cleaning, inspection and
          Description                Part No.        repair (CIR)  manual        CIR manual        CIR manual
                                                            section              inspection
----------------------------------------------------------------------------------------------------------------
Case, Diffuser, Outer.........  All..............                 72-41-13   Inspection/Check   P/N 51A750.
                                                                              (I/C-02).
----------------------------------------------------------------------------------------------------------------

    (5) For engines with ODC part number (P/N) 50J775 or 50J930 
installed, at the next piece-part exposure after the effective date 
of this AD, replace the ODC with a part eligible for installation.

(h) Definitions

    (1) For the purpose of this AD, an ``engine shop visit'' is any 
time the ``M'' flange is separated.
    (2) For the purpose of this AD, a ``piece-part exposure'' is 
when the ODC is removed from the engine and fully disassembled.
    (3) For the purpose of this AD, a ``part eligible for 
installation'' is an ODC with P/N 50J775-001, 50J775-002, 50J930-
001, or 50J930-002.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, AIR-520 Continued Operational Safety 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 paragraph (j) 
of this AD and email 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 Carol Nguyen, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: (781) 238-7655; email: [email protected].

(k) 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) Pratt & Whitney Alert Service Bulletin PW4G-112-A72-347, 
Revision 4, dated September 1, 2022.
    (ii) [Reserved]
    (3) For service information identified in this AD, contact Pratt 
& Whitney Division, 400 Main Street, East Hartford, CT 06118; phone: 
(800) 565-0140; email: [email protected]; website: 
connect.prattwhitney.com.
    (4) You may view this service information at FAA, Airworthiness 
Products Section, Operational Safety Branch, 1200 District Avenue, 
Burlington, MA. For information on the availability of this material 
at the FAA, call (781) 238-7759.
    (5) You may view this service information that is incorporated 
by reference at the

[[Page 53409]]

National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, email: 
[email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on July 21, 2023.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-16722 Filed 8-7-23; 8:45 am]
BILLING CODE 4910-13-P


