Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2016-22-05, Amendment 39-18694 (81 FR 75686, November 1, 2016), (``AD 2016-22-05''). AD 2016-22-05 applied to certain PW PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines. The NPRM published in the Federal Register on November 19, 2018 (83 FR 58194). The NPRM was prompted by several instances of fuel leaks on PW engines with the Talon IIB combustion chamber configuration installed. The fuel leaks were the result of cracks in the fuel nozzle braze joint and cracks in the fuel manifold tube adjacent to the elbow fitting. The NPRM proposed to require initial and repetitive inspections of the affected fuel nozzles and fuel nozzle supply manifold assemblies, replacement of the affected fuel nozzles with parts eligible for installation, and the installation of new brackets and clamps on the fuel nozzle supply manifold assemblies. 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 AD. The following presents the comments received on the NPRM and the FAA's response to each comment.
Request To Identify Causes of Fuel Leaks
PW requested that we identify the two potential causes of the fuel leaks, cracks in the fuel nozzle braze joint and cracks in the fuel manifold tube adjacent to the elbow fitting, in the ``Actions Since 2016-22-05 Was Issued'' paragraph of the NPRM.
We agree that updating the ``Actions Since 2016-22-05 Was Issued'' paragraph based on the request would better identify the two potential causes of the fuel leaks. We did not update the ``Actions Since AD 2017-20-01 Was Issued'' paragraph, however, because this language is not included in this final rule. Instead, we updated the Discussion paragraph to identify the two potential causes of the leaks.
RequestTo Correct Acronym Typographical Error
PW and Delta Air Lines (Delta) requested that we correct the acronym for the ring case compressor from ``RRC'' to ``RCC'' in the Applicability paragraph of this AD.
We agree and corrected the acronym in this AD.
Request To Update the Labor Work Hours
Delta requested that we update the 16 labor work-hours identified in the ``Estimated costs'' table of this AD to match the 40 man-hours identified in the Manpower paragraph of Pratt & Whitney Service Bulletin (SB) PW4G-100-73-48, Revision No. 1, dated April 24, 2018.
We disagree. Like the service information, the ``Estimated costs'' table of this AD separates the cost of the actions. The 16 work-hours of this AD
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reflects only replacing the fuel nozzle supply manifold assemblies and installing the new clamps and brackets. These work hours do not reflect any additional actions, such as opening and closing the cowl doors or using the Aircraft Maintenance Manual (AMM). We did not change this AD.
Request To Clarify the Applicability Paragraph
SR Technics Switzerland Ltd. (SR Technics) requested that we update paragraphs (c)(1) to (4) of this AD to include the phrase ``that have SB PW4G-100-73-48 Rev. 1 not fully introduced.'' SR Technics expressed concern that operators who have replaced the fuel nozzle with an eligible part may not comply with the additional requirement to replace fuel nozzle supply manifold assemblies and install new brackets and clamps.
PW and Delta requested that we clarify that engines that have already replaced fuel nozzle part number (P/N) 51J345 per Pratt & Whitney Alert Service Bulletin (ASB) PW4G-100-A73-47, dated March 10, 2017, only have to complete the replacement of the fuel nozzle supply manifold assemblies, and the installation of new brackets and clamps on the fuel nozzle supply manifold assemblies per Pratt & Whitney SB PW4G- 100-73-48, Revision No. 1, dated April 24, 2018.
We partially agree. We disagree with including the phrase suggested by SR Technics in the Applicability of this AD because we found it clearer to move the requirement to a separate paragraph. We agree with clarifying that engines with the new fuel nozzles installed only require the installation of the new fuel nozzle supply manifold assemblies, brackets, and clamps. We revised this AD by moving the requirement to replace the fuel nozzle supply manifold assemblies and to install new brackets and clamps from paragraph (g)(2)(ii) in the NPRM into a separate paragraph (g)(3) in this AD.
Request To Publish a Separate AD
Delta requested that we publish a separate AD for the replacement of the fuel nozzle supply manifold assemblies, and the installation of new brackets and clamps on the fuel nozzle supply manifold assemblies per Pratt & Whitney SB PW4G-100-73-48, Revision No. 1, dated April 24, 2018. Delta indicated that per the Applicability paragraph of this proposed rule, engines that have already met the intent of PW ASB PW4G- 100-A73-47 and therefore do not have fuel nozzle P/N 51J345 installed are not applicable.
We disagree that it is necessary to publish a separate AD to mandate replacement of the fuel nozzle supply manifold assemblies and installation of new brackets and clamps. As noted above, however, we have revised this AD by creating a separate paragraph (g)(3) to clarify the requirement for replacement of the fuel nozzle supply manifold assemblies, and the installation of new brackets and clamps.
Request To Revise the Compliance Time
PW commented that it disagreed with the compliance time proposed in the NPRM. For replacement of the fuel nozzles, PW requested that we revise the compliance time from 24 months after the effective date of this AD, as proposed in the NPRM, to April 1, 2019. This revised compliance time would match the compliance time in Pratt & Whitney ASB PW4G-100-A73-47, dated March 10, 2017. PW reasoned that the majority of the fleet is adhering to the April 1, 2019, compliance time and extending the compliance to 24 months is too lenient.
We disagree. The PW safety risk assessment for this AD supports a compliance time of 24-months after the effective date of this AD for replacement of the fuel nozzles. Although certain operators may comply by April 1, 2019, the 24-months compliance time meets the safety intent of this AD. We did not change this AD.
PW also requested that we revise the compliance time to install the fuel nozzle supply manifold assembly, brackets, and clamps to the next shop visit, not to exceed September 30, 2024, whichever occurs first. This compliance time would also be consistent with Pratt & Whitney SB PW4G-100-73-48, Revision No. 1, dated April 24, 2018. PW reasoned that after further analysis, including reassessment of the risk associated with the vibratory stress cracking of the manifolds, they will publish a revision to their service information.
We agree. PW's analysis and updated safety risk support extending the compliance time to replace the fuel nozzle supply manifold assembly, brackets, and clamps. We revised this requirement from ``At the next shop visit or within 24 months after the effective date of this AD, whichever comes first. . . .'' to ``At the next shop visit or within 60 months after the effective date of this AD, whichever comes first. . . .''
Request To Remove Wording From Terminating Action Paragraph
PW and Delta requested that we update the Terminating Action paragraph of this AD to remove the replacement of the manifold supply assemblies and installation of the brackets and clamps. Delta noted that the fuel nozzle and fuel nozzle supply manifold assembly failure modes as described by their respective Pratt & Whitney SBs PW4G-100- A73-47 and PW4G-100-73-48 are not the same. The commenters further reasoned that the repetitive inspections specified in paragraph (g)(1) of the NPRM apply only to the fuel nozzle.
We agree. We removed the replacement of the manifold supply assemblies and installation of the brackets and clamps as terminating actions for this AD.
Request To Correct the Part Terminology for Consistency
Delta noted that we used the term ``fuel nozzle manifold supply assemblies'' and ``fuel supply manifolds'' in the NPRM and requested that the term ``fuel nozzle supply manifold assembly'' be used to be consistent with the service information.
We agree. We revised this AD to refer to ``fuel nozzle supply manifold assembly.''
Request To Separate Required Actions To Allow Alternate Tool
Delta requested that we separate the actions identified in paragraph (g)(2)(ii) of the NPRM (paragraph (g)(3) of this AD), into two steps: 1. Replace the fuel nozzle supply manifold assemblies, and 2. Install the new brackets and clamps on the fuel nozzle supply manifold assemblies. Delta reasoned that this AD specifies using service information that will only allow the use of a backup wrenchto install the fuel nozzle supply manifold assemblies. Delta and PW, however, have developed an alternate tool to install the fuel nozzle supply manifold assemblies to reduce the risk of over-torqueing.
We disagree. While the service information references a backup wrench, it does not specify the P/N of the tool to use. Therefore, 14 CFR part 43 allows for the use of alternate, FAA-approved, tools. We did not change this AD.
Request To Allow Use of Later Revisions of Service Information
Delta requested that we add the phrase ``or later per subsequent SBs'' to paragraph (h)(2) of this AD to remove the need to submit alternative methods
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of compliance requests in response to future redesigns of the fuel nozzles.
We disagree. We are authorized to require the use of service information that we have reviewed and which are published. Since later revisions of the service information are not yet published, we are not authorized to require their use. We did not change this AD.
Support for the AD
The Air Line Pilots Association expressed support for the NPRM as written.
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:
Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and
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 Pratt & Whitney ASB PW4G-100-A73-45, dated February 16, 2016; Pratt & Whitney ASB PW4G-100-A73-47, dated March 10, 2017; and Pratt & Whitney SB PW4G-100-73-48, Revision No. 1, dated April 24, 2018.Pratt & Whitney ASB PW4G-100-A73-45 describes procedures for inspecting and replacing the fuel nozzles. Pratt & Whitney ASB PW4G- 100-A73-47 describes procedures for replacing the fuel nozzle and support assembly. Pratt & Whitney SB PW4G-100-73-48 describes procedures for replacing the fuel nozzle supply manifold assemblies and installing new brackets and clamps on the manifolds. 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.
Costs of Compliance
We estimate that this AD affects 72 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 productoperators ---------------------------------------------------------------------------------------------------------------- Inspect fuel nozzles.................. 2.2 work-hours x $85 per $0 $187 $13,464
hour = $187. Open and close cowl doors (on-wing)... 1 work-hour x $85 per 0 85 6,120
hour = $85. Remove and replace (24) fuel nozzles.. 48 work-hours x $85 per 423,471 427,551 30,783,672
hour = $4,080. Remove and re-install necessary 23 work-hours x $85 per 0 1,955 140,760
hardware according to AMM. hour = $1,955. Replace Fuel Nozzle Supply Manifold 16 work-hours x $85 per 77,159 78,519 5,653,368
Assemblies and install new clamps/ hour = $1,360.
brackets. ----------------------------------------------------------------------------------------------------------------
Authority forThis 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 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
We have determined that 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.