Airworthiness Directives; Pratt & Whitney Division Turbofan Engines

[Federal Register Volume 82, Number 45 (Thursday, March 9, 2017)]
[Rules and Regulations]
[Pages 13059-13062]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-04627]



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Federal Register / Vol. 82, No. 45 / Thursday, March 9, 2017 / Rules 
and Regulations

[[Page 13059]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-8836; Directorate Identifier 2016-NE-17-AD; 
Amendment 39-18815; AD 2017-05-05]
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) PW4074, PW4074D, PW4077, PW4077D, 
PW4084D, PW4090, and PW4090-3 turbofan engines. This AD was prompted by 
an uncontained failure of a high-pressure turbine (HPT) hub during 
takeoff. This AD requires an inspection to measure the surface 
condition of the aft side web/rim fillet of HPT 1st stage hubs and 
removal from service of hubs that fail inspection. We are issuing this 
AD to correct the unsafe condition on these products.

DATES: This AD is effective April 13, 2017.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of April 13, 
2017.

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 & 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-2016-8836.

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-
8836; 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 AD, 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: Jo-Ann Theriault, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 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 PW PW4074, PW4074D, PW4077, 
PW4077D, PW4084, PW4084D, PW4090, and PW4090-3 turbofan engines. The 
NPRM published in the Federal Register on October 26, 2016 (81 FR 
74358). The NPRM was prompted by an uncontained failure of an HPT hub 
during takeoff. The NPRM proposed to require an inspection to measure 
the surface condition of the aft side web/rim fillet of HPT 1st stage 
hubs and removal from service of hubs that fail inspection. We are 
issuing this AD to prevent failure of the HPT 1st stage hub, 
uncontained hub release, damage to the engine, and damage to the 
airplane.

Comments

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

Request for Previous Credit

    All Nippon Airways (ANA), Japan Airlines (JAL), PW, and United 
Airlines (UAL) requested that we give credit for hubs inspected per PW 
Special Instruction (SI) No. 250F-16, dated June 22, 2016 or PW SI No. 
250F-16, Revision A, dated July 14, 2016.
    We agree. We added a Credit for Previous Actions paragraph to give 
credit for inspections accomplished per these SIs.

Request To Provide Risk Analysis

    ANA requested that information related to the risk analysis and 
likelihood of failure that provided the basis of this AD be added to 
the compliance section of this AD. ANA noted that the root cause of 
this event is a machining anomaly and it would like to see the FAA's 
estimate on how a machining anomaly could lead to uncontained failure 
of the HPT hub.
    We disagree. The purpose of the compliance section of an AD is to 
provide the necessary actions needed to provide an acceptable level of 
safety. The FAA does not typically provide risk assessments in an AD as 
this information is often, as is the case with this AD, considered 
proprietary. FAA's general methodology for risk analysis can be found 
in FAA AC 39-8, ``Continued Airworthiness Assessments of Powerplant and 
Auxiliary Power Unit Installations of Transport Category Airplanes.'' 
We did not change this AD.

Request To Confirm Definition

    ANA requested that we confirm that replacement of the main gearbox 
or angle gearbox is not defined as a major flange separation, which is 
the basis for an ``engine shop visit,'' as defined in the NPRM (81 FR 
74358, October 26, 2016).
    We agree. Replacement of the main gearbox or angle gearbox 
replacement does not require major flange separation and does not 
constitute an ``engine shop visit.'' We note, however, that this AD no 
longer requires inspections at engine shop visits and we removed this 
definition from this AD.

Request To Remove New HPT Hubs From Inspection Requirements

    ANA, JAL, and PW requested that paragraph (e) of this AD not 
require inspection for new HPT 1st stage hubs. These hubs include HPT 
1st stage hubs marked with detail revision number part number (P/N) 
55L901 Rev B or P/N 55L801 Rev E, or subsequent revision letters. The 
commenters indicated that per PW Service Bulletin (SB) PW4G-112-72-342, 
dated September 23, 2016, HPT hubs marked with these detail

[[Page 13060]]

revision numbers do not need to be inspected because of improvements to 
PW's inspection program.
    We disagree. The root cause of the HPT hub failure is a machining 
anomaly in the aft web/rim fillet area of the HPT 1st stage hub. 
Although manufacturing changes are being made to reduce the chance of 
this defect occurring, these changes have not been fully implemented. 
New production parts, therefore, are still susceptible to this defect. 
We did not change this AD.

Request To Revise Compliance Time for Previously-Inspected Hubs

    ANA requested that for hubs that have been previously inspected, 
but not marked, the compliance should be at the next piece-part 
exposure rather than at next engine shop visit. ANA indicated that PW 
SI No. 250F-16, dated June 22, 2016, and PW SI No. 250F-16, Revision A, 
dated July 14, 2016, do not require marking of the hubs after 
inspection. Part A, paragraph 2.C., and Part B, paragraph 1.C. of PW SB 
PW4G-112-72-342, dated September 23, 2016, however, require marking the 
parts after inspection. ANA indicated that it has some parts that have 
been inspected but not marked. ANA commented that the inspection 
interval for HPT 1st stage hubs that have already been inspected should 
be at the next piece-part exposure.
    We disagree. This AD requires a one-time replication inspection of 
HPT 1st stage hubs for machining mismatch in the aft web/rim fillet. 
Hubs that have passed this inspection do not require re-inspection. For 
those parts that were inspected using PW SI No. 250F-16, dated June 22, 
2016, or PW SI No. 250F-16, Revision A, dated July 14, 2016, we are 
providing credit for that inspection provided the hubs passed the 
inspection. We did not change this AD based on this comment.

Request To Limit Applicability by Serial Number

    UAL requested that a list of affected serial numbers be added to 
the applicability section of this AD. UAL commented that the part 
revision letter markings can wear over time and that revision numbers 
are not listed on the FAA Form 8130.
    We disagree. This AD applies to all PW PW4074, PW4074D, PW4077, 
PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. The 
applicability of this AD is not limited by part or serial number. We 
did not change this AD.

Request To Mark HPT Hubs That Have Passed Inspection

    PW requested that the PW SB PW4G-112-72-342, dated September 23, 
2016, be marked on HPT 1st stage hubs that pass the inspection required 
by this AD. This would make the AD consistent with this SB, which 
instructs operators to mark the SB number on the front turbine hub 
assembly.
    We disagree. This AD requires hub inspections but does not require 
specific part markings or record-keeping procedures. If operators can 
show that hubs have been previously inspected and passed this 
inspection, then they have complied with this AD. Each operator has the 
responsibility to establish its own record-keeping procedures. We did 
not change this AD.

Request To Define Compliance by Engine Model

    UAL requested that the compliance section of this AD identify that 
the Accomplishment Instructions, Part A, of PW SB PW4G-112-72-342, 
dated September 23, 2016, apply to PW4074D, PW4077D, PW4084D, PW4090, 
and PW4090-3 engine models and the Accomplishment Instructions, Part B, 
of this SB apply only to PW4074 and PW4077 engine models.
    We agree. We determined that revising the compliance requirements 
to make these specific to each group of engine models will make them 
clearer to the operators. We revised the compliance section of this AD 
to clarify that Part A of the Accomplishment Instructions is used to do 
the inspection for PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 
engine models, while Part B is used for PW4074 and PW4077 engine 
models.

Request To Revise Compliance Schedule

    PW, UAL, and JAL requested that we revise the compliance schedule 
to match the requirements of PW SB PW4G-112-72-342, dated September 23, 
2016. PW indicated that the compliance schedule in this SB has been 
validated by a PW risk assessment. UAL indicated there are instances 
when an engine major mating flange is separated only to address a 
different engine module and the HPT is not exposed during these times.
    We agree. We find that the compliance intervals suggested by the 
commenters still maintain an acceptable level of safety. We changed 
this AD by revising the time to perform the inspection from at the 
``next engine shop visit'' to either the ``next time the engine is 
disassembled sufficiently to expose the HPT module'' (for PW4074D, 
PW4077D, PW4084D, PW4090, and PW4090-3 models) or the ``next time the 
HPT module is disassembled sufficiently to expose the HPT 1st stage 
hub'' (for PW4074 and PW4077 models).

Support for the NPRM

    The National Transportation Safety Board commented that it supports 
the proposed rule as written.

Revision to Applicability

    We revised the applicability section of this AD by removing the 
PW4084 model engine. Although this engine is listed on Type Certificate 
Data Sheet No. E46NE, Revision 8, dated January 23, 2012, it was never 
produced.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
    <bullet> Are 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 AD.

Related Service Information Under 1 CFR Part 51

    We reviewed PW SB PW4G-112-72-342, dated September 23, 2016. This 
PW SB provides guidance on performing the HPT 1st stage hub web/rim 
fillet replication inspection and measurement for the affected HPT 
hubs. 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.

Other Related Service Information

    We also reviewed PW SI No. 250F-16, dated June 22, 2016, and PW SI 
No. 250F-16, Revision A, dated July 14, 2016. These SIs provide 
guidance on performing the replication inspection of the HPT 1st stage 
hub.

Costs of Compliance

    We estimate that this AD affects 119 engines installed on airplanes 
of U.S. registry.
    We estimate the following costs to comply with this AD:

[[Page 13061]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                    Cost per       Cost on U.S.
              Action                        Labor cost            Parts cost        product         operators
----------------------------------------------------------------------------------------------------------------
Inspection........................  1 work-hour x $85 per                  $0              $85          $10,115
                                     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.
    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):

2017-05-05 Pratt & Whitney Division: Amendment 39-18815; Docket No. 
FAA-2016-8836; Directorate Identifier 2016-NE-17-AD.

(a) Effective Date

    This AD is effective April 13, 2017.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all Pratt & Whitney Division (PW) PW4074, 
PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan 
engines.

(d) Unsafe Condition

    This AD was prompted by an uncontained failure of a high-
pressure turbine (HPT) hub during takeoff. We are issuing this AD to 
prevent failure of the HPT 1st stage hub, uncontained hub release, 
damage to the engine, and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.
    (1) After the effective date of this AD, perform the HPT 1st 
stage hub web/rim fillet replication inspection and measurement as 
follows:
    (i) For PW4074D, PW4077D, PW4084D, PW4090, and PW4090-3 engine 
models, the next time the engine is disassembled sufficiently to 
expose the HPT module, use the Accomplishment Instructions, Part A, 
paragraphs 2.A. and 2.B.(1) through 2.B.(4) of PW Service Bulletin 
(SB) PW4G-112-72-342, dated September 23, 2016, to do the 
inspection.
    (ii) For PW4074 and PW4077 engine models, the next time the HPT 
module is disassembled sufficiently to expose the HPT 1st stage hub, 
use the Accomplishment Instructions Part B, paragraphs 1.A. and 
1.B.(1) through 1.B.(4) of PW SB PW4G-112-72-342, dated September 
23, 2016, to do the inspection.
    (2) If the hub fails the inspection, remove the hub from service 
before further flight and replace with a part eligible for 
installation.

(f) Installation Prohibition

    After the effective date of this AD, do not install, or re-
install into any engine, any HPT 1st stage hub that has not been 
inspected and passed the inspection required by paragraph (e) of 
this AD.

(g) Credit for Previous Actions

    You may take credit for the replication inspection of the HPT 
1st stage hub that is required by paragraph (e)(1) of this AD, if 
you performed the inspection before the effective date of this AD 
using PW Special Instruction (SI) No. 250F-16, dated June 22, 2016, 
or PW SI No. 250F-16, Revision A, dated July 14, 2016.

(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 Jo-Ann 
Theriault, Aerospace Engineer, Engine Certification Office, FAA, 
Engine & Propeller Directorate, 1200 District Avenue, Burlington, MA 
01803; phone: 781-238-7105; fax: 781-238-7199; email: [email protected].
    (2) PW SI No. 250F-16, dated June 22, 2016, and PW SI No. 250F-
16, Revision A, dated July 14, 2016, which are not incorporated by 
reference, can be obtained from PW using the contact information in 
paragraph (j)(3) of this AD.

(j) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Pratt & Whitney Division Service Bulletin PW4G-112-72-342, 
dated September 23, 2016.
    (ii) Reserved.
    (3) For PW service information identified in this AD, contact 
Pratt & Whitney Division, 400 Main St., East Hartford, CT 06118; 
phone: 800-565-0140; fax: 860-565-5442.
    (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.
    (5) You may view this service information at the National 
Archives and Records Administration (NARA). For information on the 
availability of this material at NARA, call 202-741-6030, or go to: 
http://

[[Page 13062]]

www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on February 27, 2017.
Robert J. Ganley,
Acting Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2017-04627 Filed 3-8-17; 8:45 am]
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