Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

[Federal Register Volume 83, Number 116 (Friday, June 15, 2018)]
[Rules and Regulations]
[Pages 27889-27891]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-12830]



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Federal Register / Vol. 83, No. 116 / Friday, June 15, 2018 / Rules 
and Regulations

[[Page 27889]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0817; Product Identifier 2017-NE-30-AD; Amendment 
39-19314; AD 2018-13-02]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney Division Turbofan 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: We are adopting a new airworthiness directive (AD) for all 
Pratt & Whitney Division (PW) PW4052, PW4056, PW4060, PW4062, PW4062A, 
PW4152, PW4156A, PW4158, PW4460, and PW4462 turbofan engine models, 
including engines identified with suffixes -1C, -1E, -3, -3A, or -3B. 
This AD was prompted by the discovery of multiple cracked 4th stage 
low-pressure turbine (LPT) air seals in the fleet. This AD requires 
removal from service of certain 4th stage LPT air seals. We are issuing 
this AD to address the unsafe condition on these products.

DATES: This AD is effective July 20, 2018.

ADDRESSES: For service information identified in this final rule, 
contact Pratt & Whitney Division, 400 Main St., East Hartford, CT 
06118; phone: 800-565-0140; fax: 860-565-5442. 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 http://www.regulations.gov by searching 
for and locating Docket No. FAA-2017-0817.

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-2017-
0817; 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 final rule, the regulatory evaluation, any comments received, and 
other information. The address for Docket Operations (phone: 800-647-
5527) is 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: Jo-Ann Theriault, Aerospace Engineer, 
ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: 
781-238-7105; 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 all Pratt & Whitney 
Division (PW) PW4052, PW4056, PW4060, PW4062, PW4062A, PW4152, PW4156A, 
PW4158, PW4460, and PW4462 turbofan engine models, including engines 
identified with suffixes -1C, -1E, -3, -3A, or -3B. The NPRM published 
in the Federal Register on October 12, 2017 (82 FR 47405). The NPRM was 
prompted by the discovery of multiple cracked 4th stage LPT air seals, 
part number (P/N) 50N346, in the fleet. An investigation determined 
there is insufficient clearance to the 4th stage LPT vane cluster 
honeycomb that makes up the other half of the sealing system. Also, the 
knife edge seals are uncoated so they are more susceptible to 
overheating if a hard rub with the honeycomb occurs. The NPRM proposed 
to require the removal from service of certain 4th stage LPT air seals. 
Replacement of the air seal also requires replacement of the 4th stage 
LPT vane cluster honeycomb. This condition, if not corrected, could 
result in failure of the air seal, uncontained air seal release, damage 
to the engine, and damage to the airplane. We are issuing this AD to 
address the unsafe condition on these products.

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 Clarify Compliance Time

    United Parcel Service, United Airlines, SR Technics, Delta Airlines 
(DAL), Atlas Air, Federal Express (FedEx), and the Boeing Company 
requested that we clarify the compliance time requirement specified in 
the NPRM, paragraph (f)(1), which stated ``at the next disassembly of 
the LPT module, remove 4th stage air seal, P/N 50N346, from service and 
replace with a part eligible for installation'' because the term 
``disassembly'' is subjective and not defined elsewhere in the NPRM. 
DAL requested that we specify a compliance time in the final rule since 
paragraph (f)(1) of the NPRM indicates that the compliance actions 
should be done in accordance with the compliance times specified in the 
AD.
    We agree. We clarified that the compliance in this AD should be 
performed ``the next time the 4th stage LPT vanes are removed from the 
LPT module.''

Request for Clarification on Installation Prohibition

    DAL requested clarification on the acceptability of returning an 
LPT to service with P/N 50N346 installed if the air seal was not 
exposed at the piece-part level, because the LPT disassembly was 
limited.
    An LPT module with a 4th stage air seal, P/N 50N346, installed, may 
be returned to service, if the 4th stage LPT vanes are not removed. 
However, replacement of the 4th stage air seal is required, when the 
4th stage LPT vanes are removed. This would include, if the 4th stage 
LPT air seal was at the piece-part exposure level.

Request for Clarification on Replacement of Affected Air Seals

    Cathay Pacific Airways (CPA) asked if replacing the 4th stage LPT 
air seal, P/N 50N346, with any of the other 4th stage LPT air seals 
depicted in the Illustrated Parts Catalog (IPC) fulfills the AD 
requirement or if P/N 51N113 is the only suitable air seal for 
replacement. CPA further requested that we define what is ``a part 
eligible for installation''

[[Page 27890]]

in paragraph (f)(1) of the NPRM which states ``at the next disassembly 
of the LPT module, remove 4th stage air seal, P/N 50N346, from service 
and replace with a part eligible for installation.''
    Currently, P/N 51N113 is the only 4th stage LPT air seal suitable 
for P/N 50N346 replacement. However, new replacement air seals may be 
developed in the future. We did not change this AD.

Service Bulletin Comment

    CPA stated that PW Service Bulletin (SB) PW4ENG A72-830, Revision 
No. 1, dated May 2, 2017, listed P/N 51N113 as the only part eligible 
for installation. However, the service bulletin is not clearly listed 
in paragraph (f) of the NPRM.
    We disagree. We listed PW SB PW4ENG A72-830, Revision No. 1, dated 
May 2, 2017, in the ``Related Service Information'' section of the 
NPRM, which was the appropriate paragraph. We did not change this AD.

Request for Clarification on Applicability of AD

    Atlas Air asked if the AD applies to engines with 4th stage LPT air 
seals, P/N 51N038, 50N478, or 50N478-001, installed.
    We determined this AD only applies to engines with 4th stage LPT 
air seal, P/N 50N346, installed.

Request for Clarification on Repair Limits

    Atlas Air asked if PW Clean, Inspect, Repair (CIR) 72-53-40 
Inspection/Check-03 limits apply to the 4th stage LPT air seal, P/N 
51N113. If so, Atlas Air is concerned that the reduced knife edge might 
get scrapped due to reduced diameters.
    The intent of this AD is to install a 4th stage LPT air seal with 
reduced knife edge diameters. This AD does not impact the CIR 72-53-40 
Inspection/Check-03 limits.

Request for Clarification on Re-Installation Prohibition

    Atlas Air asked if 4th stage LPT air seals, P/N 51N038, 50N478, or 
50N478-001 are prohibited from re-installation.
    We determined that 4th stage LPT air seals, P/N 51N038, 50N478, and 
50N478-001, are not applicable to the engines affected by this AD.

Request for Clarification on Effective Date

    SR Technics asked when this AD will become effective.
    This AD will be effective 35 days after publication in the Federal 
Register.

Request for Clarification on Part Modification

    PW stated that the new part can be obtained by modification of the 
old part as specified in PW SB PW4ENG A72-830, Revision No. 1, dated 
May 2, 2017.
    We agree. The new 4th stage LPT air seal, P/N 51N113, can be 
obtained through modification of the old air seal, P/N 50N346, as noted 
in PW SB PW4ENG A72-830, Revision No. 1, dated May 2, 2017.

Request for Clarification on Honeycomb Replacement

    DAL and FedEx note that the NPRM states ``Replacement of the air 
seal also requires replacement of the 4th stage LPT vane cluster 
honeycomb'' in the ``Discussion'' paragraph. However, paragraph (f) in 
the NPRM does not address honeycomb replacement. The commenters asked 
if the FAA intends to require the replacement of the honeycomb.
    This AD addresses the unsafe condition created by a cracked 4th 
stage LPT air seal by replacing the air seal with a part that does not 
crack. Installation of the new air seal without replacement of the 4th 
stage LPT vane cluster honeycomb results in an increased radial 
clearance between the honeycomb and air seals. This is not an approved 
configuration. Requirements for replacement of the honeycomb when an 
air seal is replaced are defined in the appropriate service 
information, such as PW CIR Manual P/N 51A357, Chapter/Section 72-53-
24, Repair-02. We did not change this AD.

Supportive Comment

    The Air Line Pilots Association International expressed support for 
this AD.

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 and for minor 
editorial changes. We have determined that these minor changes:
    <bullet> Are consistent with the intent that was proposed in the 
NPRM for addressing 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 PW SB PW4ENG A72-830, Revision No. 1, dated May 02, 
2017. The SB describes procedures for replacement or modification of 
the 4th stage LPT air seals.

Costs of Compliance

    We estimate that this AD affects 991 engines installed on aircraft 
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
----------------------------------------------------------------------------------------------------------------
Replacement of air seal............  0 work-hours x $85 per hour         $13,800         $13,800     $13,675,800
                                      = $0.
----------------------------------------------------------------------------------------------------------------

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.
    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

[[Page 27891]]

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

    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 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):

2018-13-02 Pratt & Whitney Division: Amendment 39-19314; Docket No. 
FAA-2017-0817; Product Identifier 2017-NE-30-AD.

(a) Effective Date

    This AD is effective July 20, 2018.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Pratt & Whitney Division (PW) PW4052, 
PW4056, PW4060, PW4062, PW4062A, PW4152, PW4156A, PW4158, PW4460, 
and PW4462 turbofan engine models, including engines identified with 
suffixes -1C, -1E, -3, -3A, or -3B, with 4th stage low-pressure 
turbine (LPT) air seal, part number (P/N) 50N346, installed.

(d) Subject

    Joint Aircraft System Component (JASC) Code 7240, Turbine Engine 
Combustion Section.

(e) Unsafe Condition

    This AD was prompted by the discovery of multiple cracked air 
seals. We are issuing this AD to prevent failure of the 4th stage 
LPT air seal. This unsafe condition, if not addressed, could result 
in uncontained release of the air 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

    The next time the 4th stage LPT vanes are removed from the LPT 
module, remove 4th stage air seal, P/N 50N346, from service and 
replace with a part eligible for installation.

(h) Installation Prohibition

    After the effective date of this AD, do not install any 4th 
stage LPT air seal, P/N 50N346, into any LPT module.

(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) of this AD. 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.

(j) Related Information

    For more information about this AD, contact Jo-Ann Theriault, 
Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, 
Burlington, MA 01803; phone: 781-238-7105; fax: 781-238-7199; email: 
[email protected].

(k) Material Incorporated by Reference

    None.

    Issued in Burlington, Massachusetts, on June 11, 2018.
Robert J. Ganley,
Manager, Engine and Propeller Standards Branch, Aircraft Certification 
Service.
[FR Doc. 2018-12830 Filed 6-14-18; 8:45 am]
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