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Federal Register / Vol. 86, No. 157 / Wednesday, August 18, 2021 / Rules and Regulations
UERs. The manufacturer determined that the threads on the HPC rotor shaft were not optimized for load distribution, which resulted in vibration stresses. During one occurrence, oil was released at the high-pressure turbine HPT disk bore location. The manufacturer redesigned the HPC front hub and HPC rotor shaft for increased durability and decreased vibration stress. The redesigned HPC front hub is made from nickel to help with corrosion resistance. The threads on the HPC rotor shaft were also redesigned to help distribute the load on the threads and decrease vibration stress. In the NPRM, the FAA proposed to require removal and replacement of the HPC front hub and HPC rotor shaft. The FAA is issuing this AD to address the unsafe condition on these products.

Discussion of Final Airworthiness Directive
Related Service Information
Comments The FAA received comments from one commenter, the Air Line Pilots Association, International ALPA.
ALPA supported the NPRM without change.
Conclusion The FAA reviewed the relevant data, considered the comments received, and determined that air safety requires adopting the AD as proposed.
Accordingly, the FAA is issuing this AD
to address the unsafe condition on these products. This AD is adopted as proposed in the NPRM.

The FAA reviewed Pratt & Whitney Service Bulletin SB PW1000GA72
00015400A930AD, Issue No. 001, dated May 7, 2021 PW1000GA72
00015400A930AD, and Pratt &
Whitney SB PW1000GA72000101
00B930AD, Issue No. 001, dated May 7, 2021 SB PW1000GA72000101
00B930AD. These SBs describe procedures for removing and replacing the HPC front hub and HPC rotor shaft.
Costs of Compliance The FAA estimates that this AD
affects 88 engines installed on airplanes of U.S. registry.
The FAA estimates the following costs to comply with this AD:

ESTIMATED COSTS
Action
Labor cost
Replace HPC front hub and HPC rotor shaft
Authority for This Rulemaking Title 49 of the United States Code specifies the FAAs 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 Agencys authority.
The FAA is 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.

25.75 work-hours $2,188.75.

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List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:

Authority: 49 U.S.C. 106g, 40113, 44701.

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:

16:01 Aug 17, 2021

$85

1 Is not a significant regulatory action under Executive Order 12866, 2 Will not affect intrastate aviation in Alaska, and 3 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.

Regulatory Findings
VerDate Sep<11>2014

Parts cost
Jkt 253001

39.13

Amended
2. The FAA amends 39.13 by adding the following new airworthiness directive:

20211709 Pratt & Whitney: Amendment 3921692; Docket No. FAA20210447;
Project Identifier AD202100131E.
a Effective Date This airworthiness directive AD is effective September 22, 2021.

PO 00000

Frm 00010

Fmt 4700

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$120,090

Cost per product $122,278.75

Cost on U.S.
operators $10,760,530

b Affected ADs None.
c Applicability This AD applies to Pratt & Whitney PW1519G, PW1521G, PW1521G3, PW1521GA, PW1524G, PW1524G3, PW1525G, PW1525G3, PW1919G, PW1921G, PW1922G, PW1923G, and PW1923GA model turbofan engines.
d Subject Joint Aircraft System Component JASC
Code 7230, Turbine Engine Compressor Section.
e Unsafe Condition This AD was prompted by reports of cracks in the high-pressure compressor HPC rotor shaft that resulted in in-flight shutdowns and unscheduled engine removals. The FAA is issuing this AD to prevent cracking of the HPC rotor shaft. The unsafe condition, if not addressed, could result in release of a highpressure turbine disk, damage to the engine, and damage to the airplane.
f Compliance Comply with this AD within the compliance times specified, unless already done.
g Required Action At the next engine shop visit after the effective date of this AD, remove HPC front hub, part number P/N 30G1910 or 30G3210, and HPC rotor shaft, P/N 30G1854, 30G3109, 30G4995, 30G4953, or 31G0014, from service and replace each part with a part eligible for installation.

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