This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

38941 

Vol. 86, No. 139 

Friday, July 23, 2021 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0577; Project 

Identifier AD–2021–00470–E] 

RIN 2120–AA64 

Airworthiness Directives; Pratt & 

Whitney Division Turbofan Engines 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede Airworthiness Directive (AD) 

2021–05–16, which applies to certain 

Pratt & Whitney Division (PW) PW4164, 

PW4164–1D, PW4168, PW4168–1D, 

PW4168A, PW4168A–1D, and PW4170 

model turbofan engines. AD 2021–05– 

16 requires initial and repetitive 

replacements of the low-pressure 

turbine (LPT) 4th-stage air sealing ring 

segment assemblies with parts eligible 

for installation. AD 2021–05–16 also 

requires initial and repetitive 

dimensional inspections of the LPT case 

for bulging and, depending on the 

results of the dimensional inspections, 

repair or replacement of the LPT case. 

Since the FAA issued AD 2021–05–16, 

the FAA was notified of an inadvertent 

omission in the LPT 4th-stage air sealing 

ring segment assembly part numbers. 

This proposed AD would correct this 

omission. 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 7, 

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; email: 

help24@prattwhitney.com; website: 

https://prattwhitney.com. You may view 

this service information at the 

Airworthiness Products Section, 

Operational Safety Branch, FAA, 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. 

FAA–2021–0577; 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: 

Carol Nguyen, Aviation Safety Engineer, 

ECO Branch, FAA, 1200 District 

Avenue, Burlington, MA 01803; phone: 

(781) 238–7655; fax: (781) 238–7199; 

email: carol.nguyen@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–2021–0577; Project Identifier AD– 

2021–00470–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 https://

www.regulations.gov, including any 

personal information you provide. The 

agency will also post a report 

summarizing each substantive verbal 

contact the FAA receives 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 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, 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 issued AD 2021–05–16, 

Amendment 39–21459 (86 FR 17287, 

April 2, 2021), (AD 2021–05–16), for 

certain PW PW4164, PW4164–1D, 

PW4168, PW4168–1D, PW4168A, 

PW4168A–1D, and PW4170 model 

turbofan engines with LPT 4th-stage air 

sealing ring segment assemblies, part 

number (P/N) 50N463–01 or P/N 

50N526–01, installed. AD 2021–05–16 

was prompted by six reports from the 

manufacturer concerning LPT 4th-stage 

vane cluster assemblies leaning back 

and notching into rotating LPT 4th-stage 

blades, causing some blades to fracture 

and release. These incidents resulted in 

an aborted takeoff, air turnbacks, engine 

surges, high vibrations, and unplanned 

engine removals. The incidents were 

attributed to the LPT 4th-stage air 

sealing ring segment assemblies moving 

into the LPT 4th-stage blades knife edge 

seals, resulting in damage to the ring 


khammond on DSKJM1Z7X2PROD with PROPOSALS
38942 Federal Register / Vol. 86, No. 139 / Friday, July 23, 2021 / Proposed Rules 

segment assemblies. AD 2021–05–16 

requires initial and repetitive 

replacements of the LPT 4th-stage air 

sealing ring segment assemblies with 

parts eligible for installation. AD 2021– 

05–16 also requires initial and repetitive 

dimensional inspections of the LPT case 

for bulging and, depending on the 

results of the dimensional inspections, 

repair or replacement of the LPT case. 

The agency issued AD 2021–05–16 to 

prevent damage to the LPT 4th-stage air 

sealing ring segment assemblies, the 

LPT case, and the LPT 4th-stage blades. 

The unsafe condition, if not addressed, 

could result in uncontained release of 

the LPT 4th-stage blades, damage to the 

engine, and damage to the airplane. 

Actions Since AD 2021–05–16 Was 

Issued 

Since the FAA issued AD 2021–05– 

16, the FAA was notified by a 

manufacturer of parts manufacturer 

approval (PMA) parts and that 

paragraphs (c), (g), and (h) of the AD 

should include affected PMA part 

numbers because the unsafe condition 

also applies to those parts. The FAA 

added FAA-approved equivalent part 

numbers to paragraphs (c), (g), and (h) 

of this AD to include PMA part 

numbers. 

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 Pratt & Whitney 

Alert Service Bulletin No. PW4G–100– 

A72–262, Revision No. 1, dated 

September 3, 2020 (the ASB). The ASB 

specifies procedures for replacing the 

LPT 4th-stage air sealing ring segment 

assemblies and inspecting the LPT case 

for bulging. The Director of the Federal 

Register approved the ASB for 

incorporation by reference as of May 7, 

2021 (86 FR 17287, April 2, 2021). 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 

NPRM 

This proposed AD would retain all 

the requirements of AD 2021–05–16. 

This proposed AD would add ‘‘or FAAapproved equivalent part numbers’’ to 

paragraph (c), Applicability; paragraph 

(g), Required Actions; and paragraph 

(h), Definitions, of this AD. This 

proposed AD would also add paragraph 

(i), Credit for Previous Actions, allowing 

operators to take credit for the required 

actions in paragraph (g)(4) of this AD if, 

prior to the effective date of this AD, 

operators performed dimensional 

inspections of the LPT case for bulging 

using Pratt & Whitney ASB No. PW4G– 

100–A72–262, Original Issue, dated 

October 22, 2019. 

Costs of Compliance 

The FAA estimates that this AD, if 

adopted as proposed, would affect 99 

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 

Inspect the LPT case for bulging .................... 2 work-hours × $85 per hour = $170 ............. $0 $170 $16,830 

Replace the LPT 4th-stage air sealing ring 

segment assemblies.

50 work-hours × $85 per hour = $4,250 ........ 64,592 68,842 6,815,358 

The FAA estimates the following 

costs to do any necessary repair or 

replacement that would be required 

based on the results of the proposed 

inspection. The agency has no way of 

determining the number of aircraft that 

might need these repairs or 

replacements. 

ON-CONDITION COSTS

Action Labor cost Parts cost Cost per 

product 

Repair LPT case to restore dimensions ....................... 250 work-hours × $85 per hour = $21,250 .................. $0 $21,250 

Replace the LPT case .................................................. 0 work-hours × $85 per hour = $0 ............................... 1,300,000 1,300,000 

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. 


khammond on DSKJM1Z7X2PROD with PROPOSALS
Federal Register / Vol. 86, No. 139 / Friday, July 23, 2021 / Proposed Rules 38943 

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. 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by: 

■ a. Removing Airworthiness Directive 

AD 2021–05–16, Amendment 39–21459 

(86 FR 17287, April 2, 2021); and 

■ b. Adding the following new 

airworthiness directive: 

Pratt & Whitney Division: Docket No. FAA– 

2021–0577; Project Identifier AD–2021– 

00470–E. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) action by 

September 7, 2021. 

(b) Affected ADs 

This AD replaces AD 2021–05–16, 

Amendment 39–21459 (86 FR 17287, April 2, 

2021). 

(c) Applicability 

This AD applies to Pratt & Whitney 

Division (PW) PW4164, PW4164–1D, 

PW4168, PW4168–1D, PW4168A, PW4168A– 

1D, and PW4170 model turbofan engines 

with low-pressure turbine (LPT) 4th-stage air 

sealing ring segment assemblies, part number 

(P/N) 50N463–01, P/N 50N526–01, or FAAapproved equivalent part numbers, installed. 

(d) Subject 

Joint Aircraft System Component (JASC) 

Code 7250, Turbine Section. 

(e) Unsafe Condition 

This AD was prompted by several reports 

from the manufacturer concerning LPT 4thstage vane cluster assemblies leaning back 

and notching into the rotating LPT 4th-stage 

blades, causing some blades to fracture and 

release. A manufacturer investigation into 

those reports determined that the leaning 

back of the LPT 4th-stage vane cluster 

assemblies was caused by damage to the LPT 

4th-stage air sealing ring segment assemblies. 

The FAA is issuing this AD to prevent 

damage to the LPT 4th-stage air sealing ring 

segment assemblies, the LPT case, and the 

LPT 4th-stage blades. The unsafe condition, 

if not addressed, could result in uncontained 

release of the LPT 4th-stage blades, 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 affected engines that have either the 

Talon IIA outer combustion chamber 

assembly, P/N 51J100 or P/N 51J382, or the 

Talon IIB outer combustion chamber 

assembly, P/N 51J381 or P/N 51J500, 

installed, at the next engine shop visit after 

the effective date of this AD, remove from 

service the LPT 4th-stage air sealing ring 

segment assemblies, P/N 50N463–01, P/N 

50N526–01, or FAA-approved equivalent 

part numbers, and replace with parts eligible 

for installation. 

(2) For affected engines not referenced in 

paragraph (g)(1) of this AD, at the next LPT 

overhaul after the effective date of this AD, 

remove from service the LPT 4th-stage air 

sealing ring segment assemblies, P/N 

50N463–01, P/N 50N526–01, or FAAapproved equivalent part numbers, and 

replace with parts eligible for installation. 

(3) For all affected engines, at each LPT 

overhaul after compliance with the required 

actions in paragraphs (g)(1) or (2) of this AD, 

remove from service the LPT 4th-stage air 

sealing ring segment assemblies, P/N 

50N526–01 or FAA-approved equivalent part 

numbers, and replace with parts eligible for 

installation. 

(4) During each replacement of the LPT 

4th-stage air sealing ring segment assemblies 

required by paragraphs (g)(1) through (3) of 

this AD, perform a dimensional inspection of 

the LPT case for bulging in accordance with 

the Accomplishment Instructions, paragraph 

2, of PW Alert Service Bulletin No. PW4G– 

100–A72–262 Revision No. 1, dated 

September 3, 2020 (the ASB). 

(5) If, during the dimensional inspection of 

the LPT case required by paragraph (g)(4) of 

this AD, any LPT case found to be outside 

the serviceable limits specified in Table 1: 

Serviceable Limits and Repairs of the ASB, 

repair or replace the LPT case before further 

flight. 

(h) Definitions 

For the purpose of this AD: 

(1) An ‘‘engine shop visit’’ is the induction 

of an engine into the shop for maintenance 

involving the separation of pairs of major 

mating engine flanges H through P. The 

separation of engine flanges solely for the 

purpose of transportation without subsequent 

engine maintenance does not constitute an 

engine shop visit. 

(2) An ‘‘LPT overhaul’’ is when the LPT 

rotor is removed from the engine, all four 

disks are removed from the LPT rotor, and all 

blades are removed from the disks. 

(3) ‘‘Parts eligible for installation’’ are LPT 

4th-stage air sealing ring segment assemblies, 

P/N 50N526–01, or FAA-approved equivalent 

part numbers, with zero flight cycles since 

new or with a P/N not mentioned in this AD. 

(i) Credit for Previous Actions 

You may take credit for the dimensional 

inspection of the LPT case for bulging 

required by paragraph (g)(4) of this AD if the 

inspection was performed before the effective 

date of this AD using PW ASB No. PW4G– 

100–A72–262 Original Issue, dated October 

22, 2019. 

(j) 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. 

Information may be emailed to: ANE-ADAMOC@faa.gov. 

(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. 

(k) Related Information 

(1) For more information about this AD, 

contact Carol Nguyen, Aviation Safety 

Engineer, ECO Branch, FAA, 1200 District 

Avenue, Burlington, MA 01803; phone: (781) 

238–7655; fax: (781) 238–7199; email: 

carol.nguyen@faa.gov. 

(2) For service information identified in 

this AD, contact Pratt & Whitney, 400 Main 

Street, East Hartford, CT 06118; phone: (800) 

565–0140; email: help24@prattwhitney.com; 

website: https://prattwhitney.com. 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 July 16, 2021. 

Lance T. Gant, 

Director, Compliance & Airworthiness 

Division, Aircraft Certification Service. 

[FR Doc. 2021–15518 Filed 7–22–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0574; Project 

Identifier 2019–SW–073–AD] 

RIN 2120–AA64 

Airworthiness Directives; He ́licopte`res 

Guimbal Helicopters 

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 He ́licopte`res Guimbal Model 

CABRI G2 helicopters. This proposed 

AD was prompted by a report that, 


khammond on DSKJM1Z7X2PROD with PROPOSALS