Airworthiness Directives; CFM International S.A. Turbofan Engines

[Federal Register Volume 82, Number 134 (Friday, July 14, 2017)]
[Rules and Regulations]
[Pages 32447-32450]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-14545]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9592; Directorate Identifier 2016-NE-30-AD; 
Amendment 39-18952; AD 2017-14-08]
RIN 2120-AA64


Airworthiness Directives; CFM International S.A. Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
CFM International S.A. (CFM) CFM56-3, -3B, and -3C turbofan engines. 
This AD was prompted by a report of dual-engine loss of thrust control 
(LOTC) that resulted in an air turn back. This AD requires initial and 
repetitive checks of the variable stator vane (VSV) actuation system in 
the high-pressure compressor (HPC). We are issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective August 18, 2017.

ADDRESSES: For service information identified in this final rule, 
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: [email protected]. You may view this 
service information at the FAA, Engine & Propeller Directorate, 1200 
District Avenue, Burlington, MA. For information on the availability of 
this material at the FAA, call 781-238-7125. It is also available on 
the Internet at http://www.regulations.gov by searching for and 
locating Docket No. FAA-2016-9592.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2016-
9592; or in person at the Docket Management Facility between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The AD docket 
contains this final rule, the regulatory evaluation, any comments 
received, and other information. The address for the Docket Office 
(phone: 800-647-5527) is Document Management Facility, U.S. Department 
of Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: David Bethka, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 1200 
District Avenue, Burlington, MA 01803; phone: 781-238-7129; fax: 781-
238-7199; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 by adding an AD that would apply to certain CFM CFM56-3, -3B, 
and -3C turbofan engines. The NPRM published in the Federal Register on 
March 9, 2017 (82 FR 13077). The NPRM was prompted by a report of dual-
engine LOTC that resulted in an air turn back. The NPRM proposed to 
require initial and repetitive checks of the VSV actuation system in 
the HPC. We are issuing this AD to maintain the actuators ability to 
fully reach commanded position, and prevent LOTC and reduced control of 
the airplane.

Comments

    We gave the public the opportunity to participate in developing 
this final rule. The following presents the comments received on the 
NPRM and the FAA's response to each comment.

Request To Change Applicability

    CFM, Boeing, Anonymous, and Jet2.com requested that the 
Applicability paragraph be limited to engines operating in the tropical 
regions specified in CFM Service Bulletin (SB) CFM56-3 S/B 72-1169, 
rather than fleet-wide. A change of applicability to specific regions 
would avoid unnecessary burden for operators that do not fly in 
tropical zones and do not fly less than 150 hours per month.
    We disagree. Operators may experience high moisture environments 
outside of the specified tropical zone that is described in CFM SB 
CFM56-3 S/B 72-1169. Operators that are outside of the specified 
tropical zone have experienced restricted VSV movement events. We did 
not change this AD.

[[Page 32448]]

Request To Change Service Information

    Milan Pavlovic requested that we include the CFM CFM56-3 Engine 
Shop Manual (ESM) 72-32-00 procedure for VSV pull force checks, as an 
acceptable method of compliance, in paragraph (f)(2) of this AD. The 
change is requested to allow the pull force check at the modular level, 
using the ESM procedure.
    We partially agree. We agree that performing the pull force check 
of the VSV system per the ESM is acceptable. We disagree with including 
a statement in paragraph (f)(2) because paragraph (f)(2) does not refer 
to any service information.

Request To Change Compliance

    Milan Pavlovic requested that we allow the replacement of an 
affected stator case with an HPC stator case (that passes the pull 
force check) in lieu of a repaired case. The proposed Compliance 
paragraph (f)(2)(i) states: ``If any stage requires more than 100 lbs. 
force to move the actuation ring, ream the VSV bores and apply anti-
corrosion coating to stage 1, 2 and 3, prior to further flight.'' This 
statement is interpreted as incorporation of CFM CFM56-3 ESM 72-32-01, 
Repair 031 is the mandated action and therefore the only acceptable 
action to satisfy the AD compliance requirements. Would replacement of 
the stator case assembly with a serviceable stator case assembly, that 
has not had CFM CFM56-3 ESM 72-32-01, Repair 031 performed, be 
considered an acceptable alternate action providing the pull force 
check is performed on the replacement stator case assembly and is found 
to be less than 75 lbs. in each stage?
    The commenter feels that replacement with a stator case that passes 
the pull force check is an additional action that would satisfy the AD 
requirements. The replacement case would be subject to the repetitive 
checks specified in paragraph (f)(3).
    We partially agree. We disagree that using any specific service 
information to comply this AD is mandated. We agree that the 
installation of a replacement HPC stator case that passes the VSV pull 
force check with measurements of 75 lbs. or less is acceptable. We 
changed paragraph (f)(2)(i) of this AD accordingly.

Request To Change Service Information Date

    CFM requested that we cite the latest revision date of CFM SB 
CFM56-3 S/B 72-1169, in the Service Information section.
    We agree. The NPRM included an earlier revision date. This AD now 
references CFM SB CFM56-3 S/B 72-1169, Revision 01, dated November 4, 
2016.

Request To Change Service Information Date

    CFM requested that we refer to the latest revision of CFM CFM56-3 
ESM 72-32-01, Repair 031, in the Service Information section. The 
latest CFM CFM56-3 ESM 72-32-01, Repair 031, revision is dated December 
15, 2016.
    We agree. The NPRM referenced an out of date ESM repair. This AD 
now references CFM CFM56-3 ESM 72-32-01, Repair 031, dated December 15, 
2016.

Request To Change Applicability

    CFM and Milan Pavlovic noted that early configurations of the 
CFM56-3 engines were released with titanium HPC stator cases, which are 
not susceptible to corrosion in VSV bores. An additional commenter asks 
if the AD should affect steel stator cases only. CFM recommends 
applicability be noted as CFM56-3 engines with steel HPC cases with P/
Ns 1499M30G01, 1499M30G02, 1499M30G03, or 1676M88G01. CFM's experience 
indicates that the titanium HPC cases do not experience VSV bore 
corrosion, and therefore do not experience restricted VSV movement due 
to bore corrosion.
    We agree. Titanium HPC cases do not experience restricted VSV 
movement due to VSV bore corrosion. We changed this AD to specify that 
it is applicable to CFM56-3, -3B, and -3C turbofan engines with steel 
HPC stator cases, P/Ns 1499M30G01, 1499M30G02, 1499M30G03, or 
1676M88G01, installed.

Request To Change the Unsafe Condition Paragraph

    CFM proposes that we change the language in the Discussion section 
to state that the VSV resistance due to the corrosion may lead to an 
inability of the actuator to fully reach commanded position. The 
description should more accurately describe the problem. VSV actuators 
do not fail due to corrosion, but do exhibit limited range of movement.
    We agree. The statement of ``failure of VSV actuators'' is an 
incomplete description of the problem. We revised the Discussion 
section and paragraph (e) of this AD to clarify.

Request To Change Related Service Information

    CFM requested that we change the Related Service Information 
section, which highlights that CFM SB CFM56-3 S/B 72-1169, Revision 01, 
dated November 4, 2016, describes a procedure to examine the VSV bore 
on the inside of the HPC case. While this is correct, CFM proposes that 
this section highlight that CFM SB CFM56-3 S/B 72-1169 describes a 
procedure to check the resistance of the VSV system as this portion of 
the SB is most relevant.
    We agree. This AD requires a pull force check of VSV actuators. We 
changed the Related Service Information section to state that CFM SB 
CFM56-3 S/B 72-1169, Revision 01, dated November 4, 2016 describes a 
procedure to check the resistance of the VSV system.

Request To Allow Special Flight Permits

    Boeing recommends allowing a ferry flight instead of requiring 
repair prior to further flight, if a pull force check exceeds 100 lb on 
one engine. They stated that a ferry flight should be allowed if take-
off rated thrust can be achieved during a ground run, and the sister 
engine is within SB VSV pull force limits.
    We partially agree. We agree with allowing special flight permits 
because a dual engine LOTC due to VSV restricted movement is unlikely 
to occur if the sister engine is within the pull force limit. We 
disagree with changing this AD, because as written, this AD does not 
limit or prohibit special flight permits. Special flight permits are 
allowed under 14 CFR 39.23. We did not change this AD.

Request To Change Applicability

    A commenter asked why the Bahrain region is not listed as an 
affected zone for applicability of CFM SB CFM56-3 S/B 72-1169, Revision 
01, dated November 4, 2016. The commenter stated that regions other 
than tropical climate zones listed in the SB may also expose an engine 
to humid environments.
    We agree. We recognize that operation in more than one climate zone 
may contribute to VSV bore corrosion. However, this AD is applicable to 
all CFM56-3, -3B, and -3C turbofan engines with a steel HPC stator 
case, part numbers (P/Ns) 1499M30G01, 1499M30G02, 1499M30G03, or 
1676M88G01, installed, regardless of their operating environment. We 
did not change this AD.

Support for the NPRM

    The Air Line Pilots Association expressed support for the NPRM as 
written.

[[Page 32449]]

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this final rule with the changes described previously. We have 
determined that these minor changes:
    <bullet> [Agr]re consistent with the intent that was proposed in 
the NPRM for correcting the unsafe condition; and
    <bullet> Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Related Service Information

    We reviewed CFM SB CFM56-3 S/B 72-1169, Revision 01, dated November 
4, 2016. This SB describes a procedure to check the resistance of the 
VSV system. We also reviewed CFM CFM56-3 ESM 72-32-01, Repair 031, 
dated December 15, 2016. This ESM repair describes procedures for 
reaming and applying anti-corrosion paint to the VSV bores.

Costs of Compliance

    We estimate that this AD affects 460 engines installed on airplanes 
of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                       Cost per    Cost on U.S.
                Action                            Labor cost             Parts cost    product       operators
----------------------------------------------------------------------------------------------------------------
Inspection of the HPC VSV actuation     2 work-hours x $85 per hour =            $0         $170         $78,200
 system.                                 $170.
----------------------------------------------------------------------------------------------------------------

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.
    We are 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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska to the extent 
that it justifies making a regulatory distinction, and
    (4) 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.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 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 adding the following new airworthiness 
directive (AD):

2017-14-08 CFM International S.A.: Amendment 39-18952; Docket No. 
FAA-2016-9592; Directorate Identifier 2016-NE-30-AD.

(a) Effective Date

    This AD is effective August 18, 2017.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to CFM International S.A. (CFM) CFM56-3, -3B, 
and -3C turbofan engines with steel high-pressure compressor (HPC) 
stator case, part numbers (P/Ns)1499M30G01, 1499M30G02, 1499M30G03, 
or 1676M88G01, installed.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7230, Turbine Engine 
Compressor Section.

(e) Unsafe Condition

    This AD was prompted by a report of dual engine loss of thrust 
control (LOTC) that resulted in an air turn back. We are issuing 
this AD to maintain the actuators ability to fully reach commanded 
position, and prevent LOTC and reduced control of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done. Within 12 months after the effective date of 
this AD:
    (1) Inspect the affected engines to determine if the compressor 
front stator case is marked with ``RP031'' adjacent to the part 
number. If the case is marked with ``RP031,'' no further action is 
required. If the case is not marked with ``RP031,'' follow the 
remaining steps in paragraph (f) of this AD.
    (2) Perform an initial pull force check of stage 1, stage 2, and 
stage 3 of the compressor variable stator vane (VSV) actuation 
system.
    (i) If any stage requires more than 100 lb force to move the 
actuation ring, ream the VSV bores and apply anti-corrosion coating 
to stages 1, 2, and 3, prior to further flight, or replace with an 
HPC stator case that is eligible for installation and passes the VSV 
pull force check with measurements of 75 lb or less.
    (ii) If any stage requires more than 75 lb, but less than or 
equal to 100 lb force to move the actuation ring, repeat the 
inspection within 3 months since last inspection.
    (iii) If all stages require 75 lb force or less to move the 
actuation rings, repeat the inspection within 12 months since last 
inspection.
    (3) Thereafter, continue to perform repetitive pull force checks 
of stages 1, 2, and 3 of the compressor VSV actuation system and 
disposition as specified in paragraphs (2)(i) through (iii) of this 
AD.

(g) Optional Terminating Action

    Reaming the VSV bores and applying anti-corrosion coating, as 
specified in paragraph

[[Page 32450]]

(f)(2)(i) of this AD, is terminating action to the repetitive 
inspections required by paragraph (f)(3) of this AD.

(h) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, may approve AMOCs 
for this AD. Use the procedures found in 14 CFR 39.19 to make your 
request. You may email your request to: [email protected].

(i) Related Information

    (1) For more information about this AD, contact David Bethka, 
Aerospace Engineer, Engine Certification Office, FAA, Engine & 
Propeller Directorate, 1200 District Avenue, Burlington, MA 01803; 
phone: 781-238-7129; fax: 781-238-7199; email: [email protected].
    (2) CFM Service Bulletin CFM56-3 S/B 72-1169, Revision 01, dated 
November 4, 2016; and CFM CFM56-3 Engine Shop Manual 72-32-01, 
Repair 031, dated December 15, 2016, can be obtained from CFM using 
the contact information in paragraph (i)(3) of this proposed AD.
    (3) 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: [email protected].
    (4) You may view this service information at the FAA, Engine & 
Propeller Directorate, 1200 District Avenue, Burlington, MA. For 
information on the availability of this material at the FAA, call 
781-238-7125.

    Issued in Burlington, Massachusetts, on July 6, 2017.
Robert J. Ganley,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-14545 Filed 7-13-17; 8:45 am]
 BILLING CODE 4910-13-P

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