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Federal Register / Vol. 86, No. 96 / Thursday, May 20, 2021 / Rules and Regulations
Request To Add a Terminating Action AAL requested that the FAA update paragraph g1 of this AD to include, Accomplishment of these instructions are considered terminating action to this AD. AAL reasoned that this statement provides specific closure since the corrective action has been clearly defined and approved by the FAA. AAL
suggested this maintenance action is not recurring and, as such, would constitute an appropriate terminating action.
The FAA disagrees with adding the terminating action statement.
Performing the actions required by this AD achieves compliance with this AD.
A statement of terminating action is unnecessary.
Request To Clarify Compliance MTU commented that this AD
describes actions to be performed if damage is found, but does not describe actions to be performed when damage is not found as specified in CFM SB
CFM567B S/B 721054, Revision 01, dated January 15, 2020. MTU asked if the AD could reference action that needs to be performed when the engine is inducted and disassembled for reasons other than HPT inner stationary seal issue and damage or no damage is found.
The FAA disagrees with requiring actions that are not related to the unsafe condition described in this AD. The HPT inner stationary seal is not typically exposed unless the engine is undergoing an engine shop visit.
However, if damage to the HPT inner stationary seal is found during inspections not related to this AD, the ESM provides criteria to determine appropriate action.
Request To Incorporate AC 20176A in Service Information AAL and Delta requested that CFM
incorporate AC 20176A into both CFM
SB CFM565B S/B 720952, Revision 01, dated January 15, 2020, and CFM SB
CFM567B S/B 721054, Revision 01, dated January 15, 2020, for the purpose of . . . distinguishing which steps in an SB will have a direct effect on detecting, preventing, resolving, or eliminating the unsafe condition identified in an AD. The commenters reasoned that CFM should identify the steps required for compliance RC in the service information. AAL added that the RC designation reduces global AMOCs and streamlines the accomplishment of key tasks while meeting strict regulatory compliance.
The FAA agrees that adding the RC
designation to the required service information steps provides clarity to the
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operators. CFM added the RC
designation to CFM SB CFM565B S/B
720952, Revision 01, dated January 15, 2020, and CFM SB CFM567B S/B 72
1054, Revision 01, dated January 15, 2020. The FAA did not change this AD.
Request To Update References to the ESM
Delta requested that the FAA update paragraphs c2 and h2 of this AD
to reference the CFM565B ESM and the CFM567B ESM entirely, rather than specific repair tasks within the ESMs.
Delta reasoned that the CFM565B ESM
and CFM567B ESM might change in future revisions.
The FAA disagrees with changing the references from the specific repair tasks.
Paragraph c2, Applicability, and paragraph h2, Definitions, of this AD
refer to specific repair tasks within CFM565B ESM and CFM567B ESM
that are required to return a HPT inner stationary seal to service. The FAA did not change this AD, but will consider requests for AMOCs if the repair tasks change in future revisions of the ESM.
Comment on Revising Service Information CFM stated that they would update CFM SB CFM565B S/B 720952 and CFM SB CFM567B S/B 721054 based on feedback from operators. CFM
indicated it would update the definition of shop visit to clarify that replacing a fan disk is not considered a shop visit.
CFM further indicated that it would clarify that if honeycomb separation is found, then the HPT blades may be scrapped or overhauled. Finally, CFM
noted that it would revise the SBs by adding RC to those tasks required for compliance.
The FAA notes that it has revised this AD by referring to CFM SB CFM565B
S/B 720952, Revision 01, dated January 15, 2020, and CFM SB CFM567B S/B
721054, Revision 01, dated January 15, 2020. In addition, the FAA has reviewed the changes included in Revision 01 of these SBs and determined that these are clarifying changes only and impose no additional burden to operators.
Request To Allow Use of Later Revisions of Service Information AAL and Delta requested that the FAA add the phrase or later when referencing the service information in this AD. AAL stated that specifying or later could prevent numerous requests for alternative methods of compliance AMOCs if the manufacturer revises the service information. AAL also stated that this request aligns with paragraph 23.d of Advisory Circular No. 20
176A, Service Bulletins Related to
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Airworthiness Directives and Indicating FAA Approval on Service Documents, dated June 16, 2014 AC 20176A.
The FAA disagrees with adding language that allows the use of later revisions of service information when performing the required actions of this AD. Later revisions of the service information have not been reviewed by the FAA. As noted, however, in a previous comment response, the FAA
has revised this AD by referring to the latest published revisions of the referenced service information.
Support for No Reporting Requirement AAL expressed support for the No Reporting Requirement in paragraph i of this AD.
Support for the AD
ALPA and Boeing expressed support for the AD as written.
Conclusion The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed.
Accordingly, the FAA is issuing this AD
to address the unsafe condition on these products. Except for minor editorial changes and any other changes described previously, this AD is adopted as proposed in the NPRM.
None of the changes will increase the economic burden on any operator.
Related Service Information Under 1
CFR Part 51
The FAA reviewed CFM SB CFM56
5B S/B 720952, Revision 01, dated January 15, 2020, and CFM SB CFM56
7B S/B 721054, Revision 01, dated January 15, 2020. CFM SB CFM565B S/
B 720952, Revision 01, describes procedures for repairing the CFM565B
turbofan engine HPT inner stationary seal honeycomb. CFM SB CFM567B S/
B 721054, Revision 01, describes procedures for repairing the CFM567B
turbofan engine HPT inner stationary seal honeycomb. 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 ADDRESSES.
Costs of Compliance The FAA estimates that this AD
affects 210 engines installed on airplanes of U.S. registry. Operators have the option to replace or repair the affected HPT inner stationary seal. The part cost is for replacement with a repaired HPT inner stationary seal.
The FAA estimates the following costs to comply with this AD:

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