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Federal Register / Vol. 86, No. 164 / Friday, August 27, 2021 / Proposed Rules www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this proposed AD.

requires installation of crushable sleeve spacers on the bolts. The agency issued AD 20110702 to prevent an LPT blade failure that could result in uncontained engine debris and damage to the airplane.

Confidential Business Information CBI is commercial or financial information that is both customarily and actually treated as private by its owner.
Under the Freedom of Information Act FOIA 5 U.S.C. 552, CBI is exempt from public disclosure. If your comments responsive to this NPRM
contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI
as PROPIN. The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI
should be sent to Nicholas Paine, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

Actions Since AD 20110702 Was Issued Since the FAA issued AD 201107
02, the agency received a report of an MD82 airplane, equipped with JT8D
217C model turbofan engines that, on approach to Taipei Songshan Airport, experienced an engine surge on the number one engine resulting in LPT
blade fracture and uncontained LPT
blade failure. An inspection by the manufacturer determined that this event was caused by shroud notch wear of the LPT blades, which led to changes in the vibration mode and subsequent highcycle fatigue of the airfoil. In addition to this event, the FAA received reports of five events that involved uncontained failure of the LPT blades on the affected engines. Based on its investigation of these events, P&W determined that revised or more restrictive inspection thresholds and replacement intervals of the 3rd-stage and 4th-stage LPT blades are necessary and revised its service information accordingly.

Background The FAA issued AD 20110702, Amendment 3916639 76 FR 16526, March 24, 2011, AD 20110702, for all P&W JT8D209, JT8D217, JT8D
217A, JT8D217C, and JT8D219 model turbofan engines. AD 20110702 was prompted by nine reports of failure of Tinidur material LPT-to-exhaust case bolts. AD 20110702 requires initial and repetitive torque inspections of the 3rd-stage and 4th-stage LPT blades, replacement of the LPT blade if wear limits are exceeded, and replacement of the LPT-to-exhaust case bolts and nuts with longer bolts and nuts made of Tinidur material. AD 20110702 also
FAAs Determination The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
Related Service Information Under 1
CFR Part 51
The FAA reviewed Pratt & Whitney Alert Service Bulletin ASB No. JT8D
A6224, Revision No. 7, dated August 26, 2019. This service information specifies procedures for the initial and repetitive torque inspections of the 3rd-stage and 4th-stage LPT blades for shroud notch wear at revised inspection thresholds and intervals. This service information is reasonably available because the
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interested parties have access to it through their normal course of business or by the means identified in ADDRESSES.
Other Related Service Information The FAA reviewed Pratt & Whitney ASB No. JT8D A6494, Revision No. 1, dated January 26, 2010, Pratt & Whitney ASB JT8D A6507, dated November 2, 2020, and Sections 725312 through 725313 of Pratt & Whitney Engine Maintenance Manual EMM, Part No.
773128, Revision 107, dated October 15, 2020. Pratt & Whitney ASB No. JT8D
A6494, Revision No. 1, dated January 26, 2010, describes procedures for replacing the LPT-to-exhaust case bolts and nuts and installing the crushable sleeve spacers. Pratt & Whitney ASB
JT8D A6507, dated November 2, 2020, describes procedures for replacing the 3rd-stage and 4th-stage LPT blades.
Sections 725312 through 725313 of Pratt & Whitney EMM, Part No. 773128, Revision 107, dated October 15, 2020, describe procedures for inspecting and repairing the 3rd-stage and 4th-stage LPT blades.
Proposed AD Requirements in This NPRM
This proposed AD would retain certain requirements of AD 20110702.
This proposed AD would require an initial torque inspection of certain 3rdstage LPT blades and repetitive torque inspections of 4th-stage LPT blades for shroud notch wear at revised inspection thresholds and intervals. This proposed AD would also require replacement of the 3rd-stage and 4th-stage LPT blades before accumulating 5,000 hours timein-service.
Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 42
engines installed on airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this proposed AD:

lotter on DSK11XQN23PROD with PROPOSALS1

ESTIMATED COSTS
Action
Labor cost
Inspect 3rd-stage and 4th-stage LPT blades
Replace 3rd-stage and 4th-stage LPT blades

1 work-hour $85 per hour = $85 ..
150 work-hours $85 per hour =
$12,750.
1.5 work-hours $85 per hour =
127.50.

Replace the LPT-to-exhaust case bolts and nuts and install the crushable sleeve spacers.

Authority for This Rulemaking Title 49 of the United States Code specifies the FAAs authority to issue
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Parts cost
rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII,
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Fmt 4702

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Cost per product
Cost on U.S.
operators
$0
350,000

$85
362,750

$3,570
15,235,500

4,576

4,703.50

197,547

Aviation Programs, describes in more detail the scope of the Agencys authority.

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