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

8499 

Vol. 90, No. 19 

Thursday, January 30, 2025 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2025–0011; Project 

Identifier AD–2024–00618–R] 

RIN 2120–AA64 

Airworthiness Directives; Robinson 

Helicopter Company Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede Airworthiness Directive (AD) 

2024–19–11, which applies to all 

Robinson Helicopter Company Model 

R44 and R44 II helicopters. AD 2024– 

19–11 requires visually inspecting a 

certain flex plate assembly (flex plate) 

and certain clutch shaft forward yokes 

(yokes), including each flex plate bolt, 

and depending on the results, taking 

corrective actions. AD 2024–19–11 also 

requires removing certain yokes from 

service within a specified threshold, or 

as an alternative, performing in-depth 

inspections. Since the FAA issued AD 

2024–19–11, it has been determined that 

clarifications regarding the alternative 

inspections are necessary. This 

proposed AD would retain all the 

requirements of AD 2024–19–11 and 

would clarify that the alternative 

inspections are repetitive and add a 

particular paint remover option to use 

when performing those alternative 

inspections. 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 March 17, 2025. 

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 under Docket 

No. FAA–2025–0011; 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. 

Related Material: 

• For Robinson material identified in 

this proposed AD, contact Robinson 

Helicopter Company, Technical Support 

Department, 2901 Airport Drive, 

Torrance, CA 90505; phone: (310) 539– 

0508; fax: (310) 539–5198; email: ts1@

robinsonheli.com; website: 

robinsonheli.com. 

FOR FURTHER INFORMATION CONTACT: Eric 

Moreland, Aviation Safety Engineer, 

FAA, 3960 Paramount Boulevard, 

Lakewood, CA 90712; phone: (562) 627– 

5364; email: Eric.R.Moreland@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 the ADDRESSES section. Include 

‘‘Docket No. FAA–2025–0011; Project 

Identifier AD–2024–00618–R’’ 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 revise 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 

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 Eric Moreland, 

Aviation Safety Engineer, FAA, 3960 

Paramount Boulevard, Lakewood, CA 

90712; phone: (562) 627–5364; email: 

Eric.R.Moreland@faa.gov. 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 2024–19–11, 

Amendment 39–22853 (89 FR 78785, 

September 26, 2024) (AD 2024–19–11), 

for all Robinson Helicopter Company 

Model R44 and R44 II helicopters. AD 

2024–19–11 was prompted by reports of 

a fractured yoke on the main rotor (M/ 

R) drive due to fatigue cracking. 

AD 2024–19–11 requires visually 

inspecting flex plate part number (P/N) 

C947–1, yoke P/N C907–1 or C907–2, as 

applicable, yoke P/N C908–1, and each 

flex plate bolt, and depending on the 

results, replacing parts. AD 2024–19–11 

also requires removing yoke P/N C907– 

1 or C907–2, as applicable, from service 

before reaching a specified threshold or, 

as an alternative to removing the part 

from service, using a 10X or higher 

power magnifying glass, visual 

inspecting the yoke and, depending on 

the results, magnetic particle inspecting 

the yoke or replacing parts. The FAA 

issued AD 2024–19–11 to detect fatigue 

cracking on the yoke, which if not 

addressed, could result in loss of M/R 

drive and subsequent loss of control of 

the helicopter. 


lotter on DSK11XQN23PROD with PROPOSALS1
8500 Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 

Actions Since AD 2024–19–11 Was 

Issued 

Since the FAA issued AD 2024–19– 

11, the FAA has determined that 

clarification regarding the alternative 

yoke inspections and the addition of a 

particular paint remover option to use 

when performing the alternative 

inspections are necessary. This 

proposed AD clarifies that the 

alternative inspections are repetitive 

and adds the option to use Bonderite 

stripper S–ST 5251 instead of Cee-Bee 

stripper A–292 since Cee-Bee stripper 

A–292 could be difficult for some 

operators to obtain. 

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 Material 

The FAA reviewed Robinson 

Helicopter Company R44 Maintenance 

Manual and Instructions for Continued 

Airworthiness, Volume 1, Chapter 2 and 

Chapter 23, dated September 2023, 

which specifies procedures for 

inspecting the yoke and flex plate of the 

M/R drive, removing paint, applying 

torque, and performing a magnetic 

particle inspection. 

Proposed AD Requirements in This 

NPRM 

This proposed AD would retain all 

requirements of AD 2024–19–11 and 

update the alternative action to 

repetitively inspect a yoke that has 

reached the specified threshold instead 

of replacing it. 

Costs of Compliance 

The FAA estimates that this AD, if 

adopted as proposed, would affect 1,725 

helicopters of U.S. registry. The FAA 

estimates the following costs to comply 

with this proposed AD. Labor costs are 

estimated at $85 per work-hour. 

Visually inspecting a flex plate would 

take 0.25 work-hour for an estimated 

cost of $21 per helicopter and $36,225 

for the U.S. fleet. If required, replacing 

a flex plate would take 1 work-hour and 

parts would cost $1,240 for an estimated 

cost of $1,325 per helicopter. 

Visually inspecting a yoke, including 

inspecting each flex plate bolt, would 

take 1.25 work-hours for an estimated 

cost of $106 per helicopter and $182,850 

for the U.S. fleet. 

Replacing a yoke would take 6 workhours and parts would cost $890 for an 

estimated cost of $1,400 per helicopter 

and $2,415,000 for the U.S. fleet, per 

replacement cycle. 

Alternatively, removing paint and 

inspecting a yoke using 10X or higher 

power magnifying glass would take 1.5 

work-hours for an estimated cost of 

$128 per helicopter. If required, 

performing a magnetic particle 

inspection would take 1.5 work-hours 

for an estimated cost of $128 per 

helicopter. 

Applying torque to a set of bolts, nuts, 

and palnuts would take 1 work-hour for 

an estimated cost of $85 per helicopter. 

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 

■ 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 

2024–19–11, Amendment 39–22853 (89 

FR 78785, September 26, 2024); and 

■ b. Adding the following new 

airworthiness directive: 

Robinson Helicopter Company: Docket No. 

FAA–2025–0011; Project Identifier AD– 

2024–00618–R. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) by March 17, 

2025. 

(b) Affected ADs 

This AD replaces AD 2024–19–11, 

Amendment 39–22853 (89 FR 78785, 

September 26, 2024). 

(c) Applicability 

This AD applies to Robinson Helicopter 

Company Model R44 and R44 II helicopters, 

certificated in any category. 

(d) Subject 

Joint Aircraft System Component (JASC) 

Code 6310, Engine/Transmission coupling. 

(e) Unsafe Condition 

This AD was prompted by reports of a 

fractured clutch shaft forward yoke (yoke) on 

the main rotor (M/R) drive due to fatigue 

cracking. The FAA is issuing this AD to 

detect fatigue cracking on the yoke. The 

unsafe condition, if not addressed, could 

result in loss of M/R drive and subsequent 

loss of control of the helicopter. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Required Actions 

(1) Within 100 hours time-in-service (TIS) 

after the effective date of this AD, accomplish 

the actions required by paragraphs (g)(1)(i) 

through (iii) of this AD. 

(i) Visually inspect forward flex plate 

assembly part number (P/N) C947–1 (flex 

plate) for any loose fasteners, cracks, fretting, 

corrosion, wear, and to ensure that the 

washers are bonded to both sides of each flex 

plate arm, in the areas depicted in Figure 1 

to paragraph (g)(1)(i) of this AD. If there is 

any loose fastener (can be moved by hand), 

crack, fretting, corrosion, or wear that 

consists of the washers not securely bonded 

to both sides of each flex plate arm, before 

further flight, remove the flex plate from 

service and replace it with an airworthy flex 

plate. 


lotter on DSK11XQN23PROD with PROPOSALS1
Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 8501 

Note 1 to paragraph (g)(1)(i): The flex plate 

may be installed in order to accomplish the 

visual inspection. 

Figure 1 to Paragraph (g)(1)(i)—Flex Plate 

Inspection 

(ii) Visually inspect yoke P/N C907–1 or 

C907–2, as applicable, and yoke P/N C908– 

1, for any cracks, corrosion, and fretting. If 

there is any crack, corrosion, or fretting, 

before further flight, remove the yoke from 

service and replace it with an airworthy 

yoke, and torque each newly-installed bolt, 

nut, and palnut P/N B330–19 using the 

torque value information in Appendix 1 to 

this AD. 

(iii) Visually inspect each flex plate bolt for 

any missing or unaligned torque stripes, 

loose fasteners, loose nuts, and to ensure that 

palnuts are installed. If there is a missing or 

unaligned torque stripe, loose fastener (can 

be moved by hand), loose nut (can be turned 

by hand), or if a palnut is not installed, 

before further flight, remove the associated 

yoke from service and replace it with an 

airworthy yoke, and torque each newlyinstalled bolt, nut, and palnut P/N B330–19 

using the torque value information in 

Appendix 1 to this AD. 

(2) Within the compliance times specified 

in Table 1 to the introductory text of 

paragraph (g)(2) of this AD, accomplish the 

actions required by paragraph (g)(2)(i) of this 

AD or, as an alternative to accomplishing the 

actions required by paragraph (g)(2)(i) of this 

AD, accomplish the actions required by 

paragraph (g)(2)(ii) of this AD within the 

same compliance times. 

BILLING CODE 4910–13–P 


lotter on DSK11XQN23PROD with PROPOSALS1EP30JA25.004</GPH>

Give special attention to 

these areas for cracks 

Inspect enUre periphery for 

cracks and corrosion. 

Inspect this area for cracks. 

Inspect area around washers 

for fretting, 
8502 Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 

Table 1 to the Introductory Text of 

Paragraph (g)(2) 


lotter on DSK11XQN23PROD with PROPOSALS1EP30JA25.005</GPH>

Helicopter Groups Compliance Times 

For Model R44 helicopters having serial Prior to accumulating 2,200 total hours 

number 0002, or 0004 through 9999 TIS on any yoke PIN C907-l or C907-2 

inclusive, except not 1140, and R44 II or within 12 years since first installation 

helicopters having serial number 1140 or of yoke PIN C907-1 or C907-2 on any 

10001 through 29999 inclusive. helicopter, whichever occurs first; or 

within 100 hours TIS after the effective 

date of this AD; whichever occurs later, 

and thereafter before accumulating 2,200 

total hours TIS on any yoke PIN C907-1 

or C907-2 or within 12 years since first 

installation of yoke PIN C907-1 or C907-

2 on any helicopter, whichever occurs 

first. 
Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 8503 

BILLING CODE 4910–13–C 

(i) Remove the yoke from service and 

replace it with an airworthy yoke, and torque 

each newly-installed bolt, nut, and palnut P/ 

N B330–19 using the torque value 

information in Appendix 1 to this AD, or 

(ii) With yoke P/N C907–1 or C907–2 

removed, as applicable, remove the paint 

from the yoke using Cee-Bee stripper A–292 

or Bonderite stripper S–ST 5251 without 

using a plastic media abrasive paint stripper 

and accomplish the actions required by 

paragraphs (g)(2)(ii)(A) and (B) of this AD. 

(A) Using 10X or higher power magnifying 

glass, visually inspect the yoke for any crack, 

seam, lap, shut, and any flaw that is open to 

the surface. If there is any crack, seam, lap, 

shut, or flaw, before further flight, remove the 

yoke from service and replace it with an 

airworthy yoke, and torque each newlyinstalled bolt, nut, and palnut P/N B330–19 

using the torque value information in 

Appendix 1 to this AD. 

(B) If the yoke is not removed from service 

as a result of the actions required by 

paragraph (g)(2)(ii)(A) of this AD, perform a 

magnetic particle inspection for any crack, 

seam, lap, shut, and any flaw that is open to 

the surface using a method in accordance 

with FAA-approved procedures. If there is 

any crack, seam, lap, shut, or flaw, before 

further flight, remove the yoke from service 

and replace it with an airworthy yoke, and 

torque each newly-installed bolt, nut, and 

palnut P/N B330–19 using the torque value 

information in Appendix 1 to this AD. 

(h) Special Flight Permit 

A one-time flight permit may be issued in 

accordance with 14 CFR 21.197 and 21.199 

to fly to a maintenance area to perform the 

required actions in this AD, provided there 

are no passengers onboard. 

(i) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, West Certification 

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 West Certification 

Branch, send it to the attention of the person 

identified in paragraph (j) of this AD. 

Information may be emailed to: AMOC@

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. 

(j) Additional Information 

For more information about this AD, 

contact Eric Moreland, Aviation Safety 

Engineer, FAA, 3960 Paramount Boulevard, 

Lakewood, CA 90712; phone: (562) 627– 

5364; email: Eric.R.Moreland@faa.gov. 

(k) Material Incorporated by Reference 

None. 

BILLING CODE 4910–13–P 


lotter on DSK11XQN23PROD with PROPOSALS1EP30JA25.006</GPH>

For Model R44 helicopters having serial 

number 30001 and subsequent. 

Prior to accumulating 2,400 total hours 

TIS on any yoke PIN C907-1 or C907-2 

or within 12 years since first installation 

of yoke PIN C907-1 or C907-2 on any 

helicopter, whichever occurs first; or 

within 100 hours TIS after the effective 

date of this AD; whichever occurs later, 

and thereafter before accumulating 2,400 

total hours TIS on any yoke PIN C907-1 

or C907-2 or within 12 years since first 

installation of yoke PIN C907-1 or C907-

2 on any helicopter, whichever occurs 

first. 
8504 Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 

Appendix 1 to AD ####–##–#### 


lotter on DSK11XQN23PROD with PROPOSALS1EP30JA25.007</GPH>

NOTE 

1. Torque val~ are ln lnch-pounds unle$S ot~ISt! ~citied. 

2. Torquf!l values lm:ludtt nut self-looking tO«J!Jll!i. 

3. mcr@ase torqut,} w!um; 10% If torqtffid at bolt hMd. 

4. Wirt indicates threads lubrlcatiftd with A257•9 antl-ooim. 

5. For etbaw and too fittings wtllch f\l!Quiro l!lilgn!'l'limlt, torqlffl to lndk:ated 

VtdUll!i, thtm tlghtoo to de11;!f$d positloo. 

6. Tolerancl'! ts ± 10% untess rangl!d$ specifloo.. 

7. Urness otherwise F,p&eift@d, thread sizes 8·32 ood sma!lm' am not used for 

primary structur@ and do not require control of torques. 

10.32 NAS6603 

NAS6803 thru NAS6608 Bob 11+·28 NAS-6604 

NAS1303 thru NAS 1308 Botts - - ----

511&.-24 NAS8605 NAS623 Sere'!A-<s 3/8-24 NAS6600 NA.81351 & NAS-1352 Scmws 

NASOOO tnru NA.SOOS Screws 7116-20 NAS6607 

11:2-20 NAS660-8 

A142 screws 

Al\1502 Screws 10.32 A14.:M, ·3, 4; AN3 

AN503 Screws AN3 Botts AN509 Scrnws 1/4-28 AN4 

AN4 Bolts 

AN6 Bolts AN525 Scrnl/V$ 318-24 AN6 

MS:24694 Scmcws AN8 Botts MS27039 Scmws 1/2-20 ANS 

10-32 8330. 7 IMS:27151-7) ----- - --- - --- STAMPED NUTS 1/4•28 8330.13 CMS:27151 • 13) 

{PAL.NUTS) 5!16-24 8330-16 !IVIS27151•Hi} Palrluts a~ t<i be used only oooe - -

and rsplaced with rm-w whtm 3/8•24 8330-19 !MS27151• 19J 

ffl!ITIOV@d. 7118-20 8330-21 IMS27151•21l 

H2·20 8330-24 jMS27151•24l 

S6fl'oot:ll!l 5 M;Mtl Straight fittings OOily 

1l4•1B 

Si!!e oot:!'l 5 

Straight: fittings only - -·---

T APEREO PIPE ~oot:@5 

THREADS 318·18 Straight fittings only 

1/2•14 

Sa@ note 5 

Straight fittings only 

3/•t.14 Slfflnot!'!S 

Straight fittings only 

10.32 AN315•3 

ROO ENO JAM NUTS 1/4-28 AN316-4 

(AN315 and AN316) 5/'16-24 AN3l&-5 

318•24 AN$l6,-,6 

50 

120 

- -~--

240 

350 

665 

995 

37 

00 

280 

795 

6-15 

11-25 

20-40 

29-00 

42-85 

54-110 

00 

1:20 

85 

HO 

HO 

220 

160 

320 

230 

460 

15 

40 

80 .......... -·· ······-

no 
Federal Register / Vol. 90, No. 19 / Thursday, January 30, 2025 / Proposed Rules 8505 

Issued on January 23, 2025. 

Steven W. Thompson, 

Acting Deputy Director, Compliance & 

Airworthiness Division, Aircraft Certification 

Service. 

[FR Doc. 2025–01949 Filed 1–29–25; 8:45 am] 

BILLING CODE 4910–13–C 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2024–2721; Project 

Identifier AD–2024–00610–E] 

RIN 2120–AA64 

Airworthiness Directives; General 

Electric Company 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 General Electric Company (GE) 

Model CF6–80E1A2, CF6–80E1A3, 

CF6–80E1A4, and CF6–80E1A4/B 

engines. This proposed AD was 

prompted by a manufacturer 

investigation that revealed certain highpressure turbine (HPT) stage 1 and HPT 

stage 2 disks were manufactured from 

powder metal material suspected to 

contain iron inclusion. This proposed 

AD would require replacement of 

affected HPT stage 1 and HPT stage 2 

disks with parts eligible for installation. 

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 March 17, 2025. 

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 under Docket 

No. FAA–2024–2721; 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: 

Alexei Marqueen, Aviation Safety 

Engineer, FAA, 2200 South 216th Street, 

Des Moines, WA 98198; phone: (781) 

238–7178; email: alexei.t.marqueen@

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 the ADDRESSES section. Include 

‘‘Docket No. FAA–2024–2721; Project 

Identifier AD–2024–00610–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 revise 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 

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 Alexei Marqueen, 

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 was notified by the 

manufacturer of the detection of iron 

inclusion in an HPT stage 2 disk 

manufactured from the same powder 

metal material used to manufacture 

certain HPT stage 1 and HPT stage 2 

disks for GE Model CF6–80E1A2, CF6– 

80E1A3, CF6–80E1A4, and CF6– 

80E1A4/B engines. Further investigation 

by the manufacturer revealed that the 

iron inclusion is attributed to 

deficiencies in the manufacturing 

process and may cause reduced material 

properties and a lower fatigue life 

capability, which may result in 

premature fracture and uncontained 

failure. The manufacturer also informed 

the FAA that additional risk 

assessments determined that there were 

no failed events associated with the 

discovery of this iron inclusion material 

on these engines, but concluded that 

replacement of the affected HPT stage 1 

and HPT stage 2 disks is necessary to 

prevent any future failed events. The 

exposure of certain HPT stage 1 and 

HPT stage 2 disks to iron inclusion, if 

not addressed, could result in 

uncontained debris 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. 

Proposed AD Requirements in This 

NPRM 

This proposed AD would require 

replacement of affected HPT stage 1 and 

HPT stage 2 disks with parts eligible for 

installation. Because affected operators 

are already aware of the proposed 

corrective action and have already 

performed the actions proposed in this 

AD, the FAA has determined that the 

compliance time to replace the affected 

HPT stage 1 and HPT stage 2 disks 

before further flight is appropriate. 

Costs of Compliance 

The FAA estimates that this AD, if 

adopted as proposed, would affect one 

engine installed on an airplane of U.S. 

registry. 

The FAA estimates the following 

costs to comply with this proposed AD: 


lotter on DSK11XQN23PROD with PROPOSALS1