Document ID: FAA-2019-1093-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: CFM International, S.A. Turbofan Engines
Posted Date: 2020-01-23T05:00Z

[Federal Register Volume 85, Number 15 (Thursday, January 23, 2020)]
[Proposed Rules]
[Pages 3871-3874]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-01158]

[[Page 3871]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-1093; Product Identifier AD-2019-00144-E]
RIN 2120-AA64

Airworthiness Directives; CFM International, S.A. 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 CFM International S.A. (CFM) LEAP-1B21, -1B23, -1B25, -1B27, -
1B28, -1B28B1, -1B28B2, -1B28B2C, -1B28B3, -1B28BBJ1, and -1B28BBJ2 
model turbofan engines. This proposed AD was prompted by reports of two 
new unsafe conditions and the need to supersede corrective actions for 
two previously addressed unsafe conditions. The FAA proposes to 
supersede AD 2018-25-09 and AD 2019-12-01, which apply to the affected 
LEAP-1B model turbofan engines. Since the FAA issued the ADs, the FAA 
received information and analysis indicating that supersedure of these 
ADs is warranted.

DATES: The FAA must receive comments on this proposed AD by February 
12, 2020.

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 http://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 CFM 
International Inc., Aviation Operations Center, 1 Neumann Way, M/D Room 
285, Cincinnati, OH 45125; phone: 877-432-3272; fax: 877-432-3329; 
email: aviation.fleetsupport@ge.com. You may view this service 
information at the FAA, Engine and Propeller Standards Branch, 1200 
District Avenue, Burlington, MA 01803. For information on the 
availability of this material at the FAA, call 781-238-7759. It is also 
available on the internet at https://www.regulations.gov by searching 
for and locating Docket No. FAA-2019-1093.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2019-
1093; 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, the regulatory evaluation, any comments received, and other 
information. The street address for Docket Operations is listed above. 
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Christopher McGuire, Aerospace 
Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: 781-238-7120; fax: 781-238-7199; email: chris.mcguire@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2019-1093; 
Product Identifier AD-2019-00144-E'' at the beginning of your comments. 
The FAA specifically invites comments on the overall regulatory, 
economic, environmental, and energy aspects of this NPRM. The FAA will 
consider all comments received by the closing date and may amend this 
NPRM because of those comments.
    The FAA understands that CFM has communicated with affected 
operators regarding the proposed corrective actions for these unsafe 
conditions. As a result, affected operators are already aware of the 
proposed corrective actions and in some cases, have already begun 
implementation. Therefore, the FAA has determined that a 20-day comment 
period is appropriate given the particular circumstances related to the 
proposed corrections of these unsafe conditions on the CFM LEAP-1B 
model turbofan engines.
    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 FAA will also post a report summarizing each substantive 
verbal contact received about this proposed AD.

Confidential Business Information

    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 Christopher McGuire, Aerospace 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.

Discussion

    The FAA has received reports of two new unsafe conditions affecting 
CFM LEAP-1B model turbofan engines: (1) Increased fuel flow through 
certain fuel nozzles due to fuel nozzle coking, potentially causing 
distress to the static structures of the high-pressure turbine (HPT) 
and in-flight shutdown (IFSD) of one or more engines; and (2) the 
potential for undetected subsurface anomalies formed during the 
manufacturing process that could result in uncontained failure of the 
HPT stage 2 disk. To address the newly identified unsafe conditions, 
the FAA is proposing this AD.
    Further, the FAA received additional information related to the 
unsafe conditions addressed by AD 2018-25-09 and AD 2019-12-01 
regarding: (1) Icing in the pressure sensor lines, potentially causing 
inaccurate pressure sensor readings and loss of thrust control; and (2) 
inadequate oil flow to the radial drive shaft (RDS) bearing, which can 
cause failure of the bearing and IFSD of one or more engines.
    Thus, this AD would also supersede the two previously issued ADs 
addressing icing in the pressure sensor lines and inadequate oil flow 
to the RDS bearing.

[[Page 3872]]

Unsafe Conditions--Fuel Nozzle Coking and Subsurface Material Anomalies

    The FAA has received reports of unsafe conditions on the CFM LEAP-
1B model turbofan engine related to fuel nozzle coking and to 
subsurface anomalies that can be present in the HPT stage 2 disk. The 
FAA has not previously issued an AD on these unsafe conditions on the 
CFM LEAP-1B model turbofan engine.

Fuel Nozzle Coking

    Two LEAP-1B model turbofan engines have experienced fuel nozzle 
coking which led to distress of HPT static structures. On one of these 
engines, fuel nozzle coking and subsequent HPT static structure 
distress led to turbine center frame (TCF) burn-through, and an engine 
IFSD while the aircraft was engaged in a ferry flight. Fuel nozzle 
coking can lead to failure of the HPT static structures, TCF case burn-
through, and in-flight shutdown of one or more engines, loss of thrust 
control, and damage to the airplane.

Subsurface Material Anomalies

    During a broad investigation by CFM into melt-related material 
anomalies, a subsurface anomaly was found in a part manufactured from 
the same material as the LEAP-1B HPT stage 2 disk. This type of 
subsurface anomaly has the potential to cause failure of the LEAP-1B 
HPT stage 2 disk. CFM introduced enhanced inspections to prevent 
failure of the HPT stage 2 disk which can lead to uncontained engine 
failure, loss of thrust control, and damage to the airplane.
    The FAA reviewed CFM's assessment of the unsafe conditions and the 
proposed corrective actions and agrees with its conclusions. Updating 
the Airworthiness Limitations Section (ALS) of the Engine Shop Manual 
and the continuous airworthiness maintenance program for the affected 
LEAP-1B model turbofan engines would be the most effective way to 
address these unsafe conditions pertaining to fuel nozzle coking and 
subsurface material anomalies. These ALS updates would require a one-
time inspection of the HPT stage 2 disk for subsurface anomalies and 
engine condition monitoring or repetitive inspections of the HPT static 
structures for fuel nozzle coking.

ADs Being Superseded: AD 2018-25-09 and AD 2019-12-01

    The FAA is proposing to supersede AD 2018-25-09 and AD 2019-12-01. 
The FAA issued AD 2018-25-09, Amendment 39-19520 (83 FR 63559, December 
11, 2018), (``AD 2018-25-09''), for all CFM LEAP-1B21, -1B23, -1B25, -
1B27, -1B28, -1B28B1, -1B28B2, -1B28B2C, -1B28B3, -1B28BBJ1, and -
1B28BBJ2 turbofan engines. The FAA issued AD 2019-12-01, Amendment 39-
19656 (84 FR 28202, June 18, 2019), (``AD 2019-12-01''), for certain 
CFM LEAP-1B21, -1B23, -1B25, -1B27, -1B28, -1B28B1, -1B28B2, -1B28B3,-
1B28B2C, -1B28BBJ1, and -1B28BBJ2 model turbofan engines.

AD 2018-25-09--Icing in Pressure Sensor Lines

    The FAA issued AD 2018-25-09 to prevent icing in the pressure 
sensor lines and inaccurate pressure sensor readings that could result 
in failure of one or more engines, loss of thrust control, and loss of 
the airplane. AD 2018-25-09 required removing certain electronic engine 
control (EEC) systems operation (OPS) and engine health monitoring 
(EHM) software and installing versions eligible for installation. AD 
2018-25-09 resulted from six aborted takeoffs on the similarly-designed 
CFM LEAP-1A model turbofan engine after those engines did not advance 
to the desired takeoff fan speed due to icing in the pressure sensor 
line.
    Since the FAA issued AD 2018-25-09, the FAA received reports of two 
temporary loss of thrust control events caused by icing in the pressure 
sensor lines. Both events occurred on affected CFM turbofan engines 
with the EEC OPS and EHM software installed per AD 2018-25-09. After 
further investigation, the operators found water and ice in the 
pressure sensor lines, which prevented the pressure sensor from 
accurately measuring the pressure. As a result, the previous CFM EEC 
OPS and EHM software update mandated by AD 2018-25-09 would be further 
modified by this AD to detect and accommodate a frozen pressure sensor 
and to prevent loss of thrust control from occurring.

AD 2019-12-01--RDS Bearing Failure

    The FAA issued AD 2019-12-01 to prevent failure of the RDS bearing, 
which could result in failure of one or more engines, loss of thrust 
control, and loss of the airplane. AD 2019-12-01 required initial and 
repetitive inspections of the TGB scavenge screens and, depending on 
the results of the inspection, possible removal of the engine from 
service. AD 2019-12-01 resulted from multiple reports of IFSDs due to 
RDS bearing failure.
    Since the FAA issued AD 2019-12-01, further investigation by CFM 
identified an additional contributing factor to the cause of the RDS 
failures. Insufficient oil supply to the radial shaft bearing and rivet 
fatigue of the cage assembly are the primary contributing factors to 
these bearing failures. The inspections that would be mandated by this 
proposed update to the ALS have a time-based limit and include in-
service limits for the affected bearings. Even though the ALS changes 
would be applicable to all LEAP-1B engines, the requirements in the ALS 
for the RDS inspections would apply only to the engines affected by AD 
2019-12-01.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed ALS data module, CFM LEAP-1B-05-21-03-01A-281B-C, 
Issue 002, dated January 9, 2020; and ALS data module, CFM LEAP-1B-05-
29-00-01A-281B-C, Issue 001, dated January 9, 2020. CFM LEAP-1B-05-21-
03-01A-281B-C describes procedures for an ultrasonic inspection of the 
HPT stage 2 disk. CFM LEAP-1B-05-29-00-01A-281B-C, describes procedures 
for inspection of the RDS bearing; monitoring and inspections of the 
fuel nozzle; and the required version of EEC system software. 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 the ADDRESSES section.

FAA's Determination

    The FAA is proposing this AD because the agency evaluated all the 
relevant information and determined the unsafe conditions described 
previously are likely to exist or develop in other products of the same 
type design.

Proposed AD Requirements

    This proposed AD would require revising the ALS of the applicable 
CFM LEAP-1B Engine Shop Manual and the operator's approved continuous 
airworthiness maintenance program.

Costs of Compliance

    The FAA estimates that this proposed AD affects 162 engines 
installed on airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

[[Page 3873]]

                                                 Estimated Costs
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                                                                                     Cost per      Cost on U.S.
               Action                         Labor cost            Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Update ALS.........................  4 work-hours x $85 per hour              $0            $340         $55,080
                                      = $340.
TGB Screen Inspection..............  1 work-hour x $85 per hour                0              85          13,770
                                      = $85.
HPT stage 2 Disk Inspection........  6 work-hours x $85 per hour               0             510          82,620
                                      = $510.
Fuel Nozzle Inspection.............  6 work-hours x $85 per hour               0             510          82,620
                                      = $510.
Pressure Sub-system Software         0.5 work-hours x $85 per                  0           42.50           6,885
 Upgrade.                             hour = $42.50.
RDS Borescope Inspection...........  2 work-hours x $85 per hour               0             170          27,540
                                      = $170.
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    The FAA estimates the following costs to do any necessary 
replacements that would be required based on the results of the 
inspection. The FAA has no way of determining the number of aircraft 
that might need these replacements:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                   Action                                 Labor cost                Parts cost        product
----------------------------------------------------------------------------------------------------------------
RDS Replacement............................  200 work-hours x $85 per hour =             $30,500         $47,500
                                              $17,000.
HPT stage 2 Disk Replacement...............  1 work-hour x $85 per hour = $85...         225,000         225,085
Replace Set of Fuel Nozzles................  40 work-hours x $85 per hour =              120,000         123,400
                                              $3,400.
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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.
    This AD is issued in accordance with authority delegated by the 
Executive Director, Aircraft Certification Service, as authorized by 
FAA Order 8000.51C. In accordance with that order, issuance of ADs is 
normally a function of the Compliance and Airworthiness Division, but 
during this transition period, the Executive Director has delegated the 
authority to issue ADs applicable to engines, propellers, and 
associated appliances to the Manager, Engine and Propeller Standards 
Branch, Policy and Innovation Division.

Regulatory Findings

    The FAA has 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) Will not affect intrastate aviation in Alaska, and
    (3) Will 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:
0
a. Removing airworthiness directive (AD) 2018-25-09, Amendment 39-19520 
(83 FR 63559, December 11, 2018), and AD 2019-12-01, Amendment 39-19656 
(84 FR 28202, June 18, 2019); and
0
b. Adding the following new AD:

CFM International S.A.: Docket No. FAA-2019-1093; Product Identifier 
AD-2019-00144-E.

(a) Comments Due Date

    The FAA must receive comments on this AD action by February 12, 
2020.

(b) Affected ADs

    This AD replaces AD 2018-25-09, Amendment 39-19520 (83 FR 63559, 
December 11, 2018), and AD 2019-12-01, Amendment 39-19656 (84 FR 
28202, June 18, 2019).

(c) Applicability

    This AD applies to all CFM International S.A. (CFM) LEAP-1B21, -
1B23, -1B25, -1B27, -1B28, -1B28B1, -1B28B2, -1B28B3, -1B28B2C, -
1B28BBJ1, and -1B28BBJ2 model turbofan engines.

(d) Subject

    Joint Aircraft System Component (JASC) Code, 7200 (Turbine/
Turboprop).

(e) Unsafe Condition

    (1) This AD was prompted by multiple reports of engine in-flight 
shutdowns (IFSDs) and defects in the related applicable systems and 
one report of a melt-related defect of the high-pressure turbine 
(HPT) stage 2 disk material. The FAA is issuing this AD to prevent:
    (i) Increased fuel flow through certain fuel nozzles leading to 
distress of the HPT static structures and IFSD of one or more 
engines;
    (ii) undetected subsurface anomalies formed during the 
manufacturing process that could lead to uncontained HPT disk 
failure;
    (iii) icing in the pressure sensor lines, inaccurate pressure 
sensor readings and loss of thrust control; and

[[Page 3874]]

    (iv) inadequate oil flow to the radial drive shaft (RDS) 
bearing, failure of the bearing, and IFSD of one or more engines.
    (2) These unsafe conditions, if not addressed, could result in 
IFSD or failure of one or more engines, loss of thrust control and 
loss of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Within 15 days after the effective date of this AD, revise the 
Airworthiness Limitations Section (ALS) of the applicable CFM LEAP-
1B Engine Shop Manual and the operator's existing approved 
continuous airworthiness maintenance program by inserting the 
following changes:
    (1) Paragraph 6.B.(2) of the CFM Engine Shop Manual (ESM) Data 
Module LEAP-1B-05-21-03-01A-281B-C, Issue 002, dated January 9, 
2020; and
    (2) paragraphs 6.B.(1), 6.B.(2), and 6.C.(1) of the CFM ESM Data 
Module LEAP-1B-05-29-00-01A-281B-C, Issue 001, dated January 9, 
2020.

(h) No Alternative Procedures or Intervals

    After the revisions required by paragraph (g) of this AD have 
been made, no alternative inspections, procedures, or intervals may 
be used unless approved as an alternative method of compliance in 
accordance with the procedures specified in paragraph (i) of this 
AD.

(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 paragraph (j)(1) of this AD. You may email your 
request to: ANE-AD-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) Related Information

    (1) For more information about this AD, contact Christopher 
McGuire, Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: 781-238-7120; fax: 781-238-7199; email: 
chris.mcguire@faa.gov.
    (2) For service information identified in this AD, contact CFM 
International Inc., Aviation Operations Center, 1 Neumann Way, M/D 
Room 285, Cincinnati, OH 45125; phone: 877-432-3272; fax: 877-432-
3329; email: aviation.fleetsupport@ge.com. You may view this 
referenced service information at the FAA, Engine & Propeller 
Standards Branch, 1200 District Avenue, Burlington, MA 01803. For 
information on the availability of this material at the FAA, call 
781-238-7759.

    Issued in Burlington, Massachusetts, on January 15, 2020.
Robert J. Ganley,
Manager, Engine & Propeller Standards Branch, Aircraft Certification 
Service.
[FR Doc. 2020-01158 Filed 1-21-20; 11:15 am]
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