[Federal Register Volume 86, Number 54 (Tuesday, March 23, 2021)]
[Proposed Rules]
[Pages 15436-15439]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05600]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0597; Project Identifier 2019-NE-05-AD]
RIN 2120-AA64


Airworthiness Directives; CFM International, S.A. Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM).

-----------------------------------------------------------------------

SUMMARY: The FAA is revising a notice of proposed rulemaking (NPRM) 
that applied to certain CFM International, S.A. (CFM) CFM56-5B, CFM56-
5C, and CFM56-7B model turbofan engines with a certain rotating air 
high-pressure turbine (HPT) front seal. This action revises the NPRM by 
requiring CFM56-5B or CFM56-7B model turbofan engines with an installed 
reconfigured rotating air HPT front seal, which was previously 
installed and operated in a CFM56-5C model turbofan engine, to follow 
the removal requirements for the CFM56-5C model turbofan engine. The 
FAA is proposing this airworthiness directive (AD) to address the 
unsafe condition on these products. Since these actions would impose an 
additional burden over those in the NPRM the agency is requesting 
comments on this SNPRM.

DATES: The FAA must receive comments on this SNPRM by May 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 SNPRM, contact CFM 
International, S.A., Aviation Operations Center, 1 Neumann Way, M/D 
Room 285, Cincinnati, OH 45125; phone: (877) 432-3272; email: 
[email protected]. 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. FAA-2019-0597; or in person at 
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The AD docket contains the NPRM, this SNPRM, 
any comments received, and other information. The street address for 
Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Christopher McGuire, Aviation Safety 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: (781) 238-7120; 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-2019-0597; Project Identifier 
2019-NE-05-AD'' 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 again 
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 
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 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 SNPRM 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 SNPRM, 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 SNPRM. Submissions containing CBI should 
be sent to Christopher McGuire, 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 an NPRM to amend 14 CFR part 39 to supersede AD 
2019-12-05, Amendment 39-19660 (84 FR 28717, June 20, 2019), (AD 2019-
12-05). AD 2019-12-05 applies to all CFM CFM56-5B, CFM56-5C, and CFM56-
7B model turbofan engines with a certain rotating air HPT front seal. 
The NPRM published in the Federal Register on October 23, 2019 (84 FR 
56709). The NPRM was prompted by cracks found in the rotating air HPT 
front seal. In the NPRM, the FAA proposed to require replacement of the 
affected rotating air

[[Page 15437]]

HPT front seal with a part eligible for installation.

Actions Since the NPRM Was Issued

    Since the FAA issued the NPRM, CFM has issued CFM Service Bulletin 
(SB) CFM56-5B S/B 72-1074, Revision 02, dated November 6, 2019; CFM SB 
CFM56-5C S/B 72-0794, Revision 02, dated November 6, 2019; and CFM SB 
CFM56-7B S/B 72-1042, Revision 02, dated November 6, 2019. These SBs 
provide service information for following the removal limits 
established for CFM56-5C model turbofan engines for CFM56-5B or CFM56-
7B model turbofan engines with a reconfigured rotating air HPT front 
seal that was previously operated in a CFM56-5C model turbofan engine.

Comments

    The following discussion presents the comments received on the NPRM 
and the FAA's response.

Request To Revise and Remove Installation Prohibition

    American Airlines, CFM, and Lufthansa Technik AG requested the FAA 
revise the language in the Installation Prohibition to specify that it 
is only applicable to those rotating air HPT front seals that have 
affected serial numbers (S/Ns). Lufthansa Technik AG also requested the 
FAA remove the Installation prohibition from this proposed rule. 
Lufthansa Technik AG indicated that this AD already requires the 
removal of rotating air HPT front seals at an interval that will 
prevent an unsafe condition.
    The FAA partially agrees. The FAA has revised this proposed AD by 
adding language to the Installation Prohibition referencing the 
specific S/Ns in the Applicability section to ensure that the rotating 
air HPT front seals affected by the Installation Prohibition are clear. 
The FAA disagrees with the request to remove the Installation 
Prohibition. The requirement to remove rotating air HPT front seals is 
necessary to address the unsafe condition and provide a drawdown period 
to remove the affected rotating air HPT front seals from service. 
Rotating air HPT front seals installed on a different HPT disk from 
which they were removed after the effective date of the AD will not 
meet the certified removal limits established in the Airworthiness 
Limitations Section.

Request To Clarify Engine and Rotating Air HPT Front Seal Intermix 
Requirements

    American Airlines requested the FAA clarify the engine and rotating 
air HPT front seal intermix requirements, since CFM has released SB 
revisions that provide guidance on rotating air HPT front seals that 
have been operated in multiple engine models.
    The FAA agrees and has revised this proposed AD. The FAA revised 
the compliance requirements in this proposed AD by adding additional 
required actions for CFM56-5C model turbofan engines with an affected 
rotating air HPT front seal that was assembled to a second or later HPT 
disk since being reconfigured.

Request To Specify No Reporting Requirement

    American Airlines requested the FAA add a paragraph to this 
proposed AD to specify that there are no reporting requirements. The 
commenter noted that the CFM SBs specify reporting information to CFM.
    The FAA disagrees. The required actions of this AD do not mandate 
the use of the referenced service information to comply with this AD. 
The reporting instructions included in the SBs are not required by this 
AD. The FAA made no change to this AD.

Request To Clarify Inclusion of Engine Models

    Lufthansa Technik AG requested the FAA provide clarification 
regarding the NPRM supersedure preamble's discussion of expanding the 
applicability of the AD to include CFM56-5B, CFM56-5C, and CFM56-7B 
model turbofan engines. The commenter indicated that those engine 
models are already included in applicability of the AD 2019-12-05.
    The NPRM supersedure preamble states that AD 2019-12-05 only 
addresses the highest risk engines with an affected rotating air HPT 
seal that has a specified number of cycles since being reconfigured. 
The NPRM supersedure proposes to expand the affected engine models to 
include all CFM CFM56-5B, CFM56-5C, and CFM56-7B model turbofan 
engines, including those engines that have fewer cycles since being 
reconfigured. The NPRM supersedure does not propose the addition of 
affected engine models to the applicability. The FAA made no change to 
this proposed AD.

FAA's Determination

    The FAA is proposing this AD after determining the unsafe condition 
described previously is likely to exist or develop in other products of 
the same type design. Certain changes described above expand the scope 
of the NPRM. As a result, it is necessary to reopen the comment period 
to provide additional opportunity for the public to comment on this 
SNPRM.

Related Service Information

    The FAA reviewed CFM Service Bulletin (SB) CFM56-5B S/B 72-1074, 
Revision 02, dated November 6, 2019; CFM SB CFM56-5C S/B 72-0794, 
Revision 02, dated November 6, 2019; and CFM SB CFM56-7B S/B 72-1042, 
Revision 02, dated November 6, 2019. CFM SB CFM56-5B S/B 72-1074, 
Revision 02, describes procedures for replacement of the affected 
rotating air HPT front seal on CFM CFM56-5B model turbofan engines. CFM 
SB CFM56-5C S/B 72-0794, Revision 02, describes procedures for 
replacement of the affected rotating air HPT front seal on CFM CFM56-5C 
model turbofan engines. CFM SB CFM56-7B S/B 72-1042, Revision 02, 
describes procedures for replacement of the affected rotating air HPT 
front seal on CFM CFM56-7B model turbofan engines.

Proposed AD Requirements in This SNPRM

    This proposed AD would retain the requirements of AD 2019-12-05 (84 
FR 28717, June 20, 2019) (AD 2019-12-05). The proposed AD would expand 
the applicability to require the replacement of affected rotating air 
HPT front seals installed on CFM CFM56-5B, CFM56-5C, and CFM56-7B model 
turbofan engines that have fewer cycles since being reconfigured than 
the engines affected by AD 2019-12-05. This proposed AD would also 
require CFM56-5B and CFM56-7B model turbofan engines with a 
reconfigured rotating air HPT front seal that was previously operated 
in a CFM56-5C model turbofan engine to follow the removal requirements 
of the CFM56-5C model turbofan engine.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect four engines installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

[[Page 15438]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Replace the rotating air HPT front      1 work-hour x $85 per           $344,600        $344,685      $1,378,740
 seal.                                   hour = $85.
----------------------------------------------------------------------------------------------------------------

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 removing Airworthiness Directive (AD) 
2019-12-05, Amendment 39-19660 (84 FR 28717, June 20, 2019), and adding 
the following new AD:

CFM International, S.A.: Docket No. FAA-2019-0597; Project 
Identifier 2019-NE-05-AD.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by May 7, 2021.

(b) Affected ADs

    This AD replaces AD 2019-12-05, Amendment 39-19660 (84 FR 28717, 
June 20, 2019).

(c) Applicability

    This AD applies to:
    (1) CFM International, S.A. (CFM) CFM56-5B1, -5B2, -5B4, -5B5, -
5B6, -5B7, -5B1/P, -5B2/P, -5B3/P, -5B4/P, -5B5/P, -5B6/P, -5B7/P, -
5B8/P, -5B9/P, -5B3/P1, -5B4/P1, -5B1/2P, -5B2/2P, -5B3/2P, -5B4/2P, 
-5B6/2P, -5B9/2P, -5B3/2P1, -5B4/2P1, -7B20, -7B22, -7B24, -7B26, -
7B27, -7B22/B1, -7B24/B1, -7B26/B1, -7B26/B2, -7B27/B1, -7B27/B3, -
7B20/2, -7B22/2, -7B24/2, -7B26/2, -7B27/2, -7B27A model turbofan 
engines with a:
    (i) Rotating air high-pressure turbine (HPT) front seal:
    (A) With part number (P/N) 1795M36P01 or P/N 1795M36P02 and 
serial numbers (S/Ns) GWNDN949 through GWNSE969 or S/Ns GWN000CE 
through GWN0990L, not including S/Ns GWN08ND7, GWN0923A, GWN0971E, 
GWN098A1, GWN098W6, GWN098W8, GWN098WA, and GWN0990G, installed, and
    (B) That has been removed from the original HPT disk and re-
assembled to a different HPT disk.
    (ii) [Reserved]
    (2) CFM CFM56-5C2, -5C2/4, -5C2/F, -5C2/F4, -5C2/G, -5C2/G4, -
5C2/P, -5C3/F, -5C3/F4, -5C3/G, -5C3/G4, -5C3/P, -5C4, -5C4/1, -5C4/
P, -5C4/1P model turbofan engines with a:
    (i) Rotating air HPT front seal:
    (A) With P/N 1795M36P01 or P/N 1795M36P02 and S/Ns GWNDN949 
through GWNSE969 or S/Ns GWN000CE through GWN0990L, not including S/
Ns GWN08ND7, GWN0923A, GWN0971E, GWN098A1, GWN098W6, GWN098W8, 
GWN098WA, and GWN0990G, installed, and
    (B) That has been removed from the original HPT disk and re-
assembled to a different HPT disk.
    (ii) [Reserved]

(d) Subject

    Joint Aircraft System Component (JASC) Code 7250, Turbine 
Section.

(e) Unsafe Condition

    This AD was prompted by cracks found in the rotating air HPT 
front seal. The FAA is issuing this AD to prevent failure of the 
rotating air HPT front seal. The unsafe condition, if not addressed, 
could result in the uncontained release of the rotating air HPT 
front seal, 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 all affected CFM CFM56-5B and CFM56-7B model turbofan 
engines:
    (i) If, on July 5, 2019 (the effective date of AD 2019-12-05), 
the rotating air HPT front seal has 7,000 cycles or greater since 
being reconfigured, remove the part from service within 50 cycles 
after July 5, 2019 (the effective date of AD 2019-12-05), or before 
further flight, whichever occurs later, and replace with a part 
eligible for installation.
    (ii) If, on July 5, 2019 (the effective date of 2019-12-05), the 
rotating air HPT front seal has between 6,001 and 6,999 cycles, 
inclusive, since being reconfigured, remove the part from service 
within 500 cycles after July 5, 2019 (the effective date of AD 2019-
12-05), but not to exceed 7,050 cycles since being reconfigured, or 
before further flight, whichever occurs later, and replace with a 
part eligible for installation.
    (iii) For all remaining CFM56-5B and CFM56-7B model turbofan 
engines, remove the rotating air HPT front seal from service before 
accumulating 6,500 cycles since being reconfigured, or within 50 
cycles after the effective date of this AD, whichever occurs later.
    (2) For all affected CFM CFM56-5C model turbofan engines:
    (i) If, on July 5, 2019 (the effective date of AD 2019-12-05), 
the rotating air HPT front seal has 4,250 cycles or greater since 
being reconfigured, remove the part from service within 25 cycles 
after July 5, 2019 (the effective date of AD 2019-12-05), within 
1,500 cycles since the last fluorescent penetrant inspection (FPI) 
of the rotating air HPT front seal, or before further flight after 
the effective date of this AD, whichever occurs later, and replace 
with a part eligible for installation.
    (ii) If, on July 5, 2019 (the effective date of AD 2019-12-05), 
the rotating air HPT front

[[Page 15439]]

seal has between 3,751 and 4,249 cycles, inclusive, since being 
reconfigured, remove the part from service within 250 cycles after 
July 5, 2019 (the effective date of AD 2019-12-05), before 
accumulating 4,275 cycles since being reconfigured, within 1,500 
cycles since the last FPI of the rotating air HPT front seal, or 
before further flight after the effective date of this AD, whichever 
occurs later, and replace with a part eligible for installation.
    (iii) For all remaining CFM CFM56-5C model turbofan engines, 
remove the rotating air HPT front seal from service before 
accumulating 4,000 cycles since being reconfigured, or within 50 
cycles after the effective date of this AD, whichever occurs later.
    (3) For CFM56-5B or CFM56-7B model turbofan engines with an 
affected rotating air HPT front seal that has been operated in a 
CFM56-5C model turbofan engine since being reconfigured, remove the 
rotating air HPT front seal from service using the cycle limits in 
paragraph (g)(2) of this AD.

(h) Definition

    For the purpose of this AD, ``reconfigured'' occurs when a 
rotating air HPT front seal has been removed from the original HPT 
disk and re-assembled to a different HPT disk.

(i) Installation Prohibition

    After the effective date of this AD, do not assemble any 
rotating air HPT front seal with greater than 0 cycles since new, 
having a S/N listed in paragraph (c) of this AD onto a HPT disk 
unless it is the same S/N HPT disk on which it has previously been 
assembled.

(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. 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.

(k) Related Information

    (1) For more information about this AD, contact Christopher 
McGuire, Aviation Safety Engineer, ECO Branch, FAA, 1200 District 
Avenue, Burlington, MA 01803; phone: (781) 238-7120; fax: (781) 238-
7199; email: [email protected].
    (2) For service information identified in this AD, contact CFM 
International, S.A., Aviation Operations Center, 1 Neumann Way, M/D 
Room 285, Cincinnati, OH 45125; phone: (877) 432-3272; email: 
[email protected]. 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 March 12, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2021-05600 Filed 3-22-21; 8:45 am]
BILLING CODE 4910-13-P