Federal Register - February 24, 2021
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Source: Federal Register
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Federal Register / Vol. 86, No. 35 / Wednesday, February 24, 2021 / Rules and Regulations
checks, the NPRM proposed to require a protrusion check and a pull-out test, and the replacement of inserts on the HMU/MEC idler adapter that fail either test. The FAA is issuing this AD to address the unsafe condition on these products.
Discussion of Final Airworthiness Directive Comments The FAA received comments from four commenters. The commenters were All Nippon Airways ANA, Delta Air Lines, Inc. DAL, FedEx Express FedEx, and Japan Airlines JAL. All commenters requested changes, some of which resulted in changes to this AD.
The following presents the comments received on the NPRM and the FAAs response to each comment.
Request To Update the Applicability DAL requested that paragraph c, Applicability, of this AD be updated to align with the effectivity in GE CF6
80C2 Service Bulletin SB 721577
R01, dated August 16, 2019 GE CF6
80C2 SB 721577 R01, which includes the part numbers P/Ns of the affected HMU/MEC idler adapters.
The FAA agrees. The FAA confirmed with the manufacturer that only the P/
Ns of the HMU/MEC idler adapter listed in GE CF680C2 SB 721577 R01 are affected. The FAA updated the applicability of this AD to include the P/Ns of the affected HMU/MEC idler adapter. The number of engines affected by this AD is unchanged from the NPRM.
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Request To Update Terminating Action DAL requested that paragraph h, Terminating Action, of this AD also terminate the initial shim check of the HMU/MEC idler adapter inserts required by paragraph g1 of this AD.
DAL reasoned that since the NPRM
proposed to allow for terminating the repetitive shim checks of the HMU/MEC
idler adapter inserts, that this AD
should add a terminating action for the initial shim check of the HMU/MEC
idler adapter inserts if the action was performed within 1,200 flight hours FHs after the effective date of this AD.
The FAA agrees. The FAA updated paragraph h of this AD to terminate the actions required by paragraph g of this AD.
Request To Remove the Shim Check DAL requested that the FAA remove the shim check of the HMU/MEC idler adapter inserts in paragraph g3ii of the NPRM. DAL reasoned that performing this shim check is not necessary because the g3ii shim check is already required by paragraph
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g3i of this AD. Additionally, DAL
stated that referencing paragraph g1
of this AD to perform the shim check may confuse operators as paragraph g1 of this AD includes the requirement to perform the shim check within 1,200 FHs after the effective date of this AD. Therefore, DAL suggested that paragraph g3ii of this AD
should only address the requirement to perform the terminating action if the shim check fails.
The FAA partially agrees. The FAA
disagrees that paragraph g3ii of this AD should only address the requirement to perform the terminating action if the shim check of the HMU/MEC idler adapter inserts fails. After retorque of the bolts at each bolt location that failed the shim check, operators must perform the shim check again. If that shim check fails, then the terminating action is required. The FAA agrees that referencing paragraph g1 of this AD
may confuse operators whether to perform the shim check after the aircraft operated for some time or within 1,200
FHs after the effective date of this AD.
The FAA updated paragraph g3ii of this AD to reference the service information when performing the shim check rather than paragraph g1 of this AD.
Request To Update Credit for Previous Actions ANA, DAL, FedEx, and JAL requested updates to paragraph i, Credit for Previous Actions, of this AD. ANA
requested adding credit for the repetitive shim checks of the HMU/MEC
idler adapter inserts and terminating action. DAL and FedEx requested credit for the terminating action. JAL
requested credit for the repetitive shim checks of the HMU/MEC idler adapter inserts, retorque of the bolts that failed the shim check, and the terminating action. The commenters reasoned that GE CF680C2 SB 721577 R00, dated October 31, 2018 GE CF680C2 SB 72
1577 R00, instructs the operator to perform the same tasks required by GE
CF680C2 SB 721577 R01. Therefore, credit should be allowed for initial and repetitive shim checks of the HMU/MEC
idler adapter inserts and the terminating action.
The FAA agrees. The FAA reviewed GE CF680C2 SB 721577 R00, and determined that the instructions are consistent with GE CF680C2 SB 72
1577 R01. The FAA updated this AD to allow credit for the initial and repetitive shim checks of the HMU/MEC idler adapter inserts, retorque of the bolts that failed the shim check, and the terminating action, if performed before
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the effective date of this AD using GE
CF680C2 SB 721577 R00.
Request for an Alternate Marking Area ANA requested that the FAA approve an alternate marking area to show compliance with performing the terminating action of this AD. ANA
stated that the marking areas indicated in GE CF680C2 SB 721577 R01, are difficult to access because many components are installed to AGB
assembly.
The FAA disagrees with approving an alternate marking area. The manufacturer provided two possible marking areas in GE CF680C2 SB 72
1577 R01, and confirmed the suitability of the areas.
Request To Not Mandate the Marking Requirement DAL requested that the FAA not mandate the provision in GE CF680C2
SB 721577 R01 to mark the HMU/MEC
idler adapter to show compliance with the terminating actions of this AD. DAL
reasoned that the NPRM did not propose to apply to all engines and therefore should not be required.
The FAA disagrees. Marking the HMU/MEC idler adapter identifies if the terminating action of this AD has been completed. As noted in a previous comment response, the FAA revised the applicability of this AD to limit applicability to affected engines with certain HMU/MEC idler adapter P/Ns installed. Operators who determine that their engines are not applicable to this AD do not need to perform the terminating action or mark the HMU/
MEC idler adapter.
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 GE CF680C2 SB
721577 R01, dated August 16, 2019.
The SB describes procedures for performing shim checks of the HMU/
MEC idler adapter and for replacing the HMU/MEC idler adapter inserts. This service information is reasonably available because the interested parties have access to it through their normal
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