[Docket No. FAA-2015-0787; Directorate Identifier 2015-NE-10-AD; Amendment 

39-18307; AD 2015-22-03] 

R!N 2120-AA64 

Ainvorthiness Directives; Pratt & Whitney Division Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are adopting a new airworthiness directive (AD) for all Pratt & 

Whitney Division (PW) PW4164, PW4168, PW4168A, PW4164C, PW4164C/B, 

PW4164-ID, PW4168-ID, PW4168A-ID, PW4170, PW4164C-ID, PW4164C/B-ID, PW4050,PW4052,PW4056,PW4060,PW4060A,PW4060C,PW4062,PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, PW4462, andPW4650 

turbofan engines including models with a "-3" suffix with a low-pressure turbine (LPT) 

4111 stage itmer air seal (lAS), part number (PIN) 51N038, installed. This AD was 

prompted by the discovery, during routine overhaul of the LPT, of cracks in the barrel 

section of the LPT 41h stage lAS. This AD requires removal of the LPT 41h stage lAS, PIN 

51N038, according to a prescribed schedule. We are issuing this AD to prevent failure of 

the LPT 4th stage lAS, which could lead to an uncontained IAS release, damage to the 

engine, and damage to the airplane. 

DATES: This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. 

ADDRESSES: For service information identified in this AD, contact Pratt & Whitney 

Division, 400 Main St., East Hartford, CT 06108; phone: (860) 565-8770; fax: (860) 565-

4503. You may view this service information at the FAA, Engine & Propeller 
searching for and locating Docket No. FAA-2015-0787; or in person at the Docket 

Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal 

holidays. The AD docket contains this AD, the regulatory evaluation, any comments 

received, and other information. The address for the Docket Office (phone: 

800-647-5527) is Document Management Facility, U.S. Department of Transportation, 

Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 

Jersey Avenue SE., Washington, DC 20590. 

FOR FURTHER INFORMATION CONTACT: Katheryn Malatek, Aerospace 

Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New 

England Executive Park, Burlington, MA 01803; phone: 781-23 8-77 4 7; fax: 781-238-

7199; email: katheryn.malatek@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by 

adding an AD that would apply to all PW PW4164, PW4168, PW4168A, PW4164C, 

PW4164C/B, PW4164-ID, PW4168-ID, PW4168A-ID, PW4170, PW4164C-ID, 

PW4164C/B-1D,PW4050,PW4052,PW4056,PW4060,PW4060A,PW4060C, 

PW4062, PW4062A, PW4152, PW4156, PW4156A, PW4158, PW4160, PW4460, 

PW4462, and PW4650 turbofan engines including models with a "-3" suffix with an LPT 

41' lAS, PIN 51N038, installed. The NPRM published in the Federal Register on June 1, 

2015 (80 FR 30963). The NPRM was prompted by nine occasions of discovering, during 

routine overhaul of the LPT, cracks in the barrel section of the LPT 41h stage lAS. The 

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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. 

Support for the NPRM 

The Boeing Company expressed support for the NPRM. 

Request to change Definitions 

United Airlines and Delta Airlines requested that the Definitions paragraph be 

changed. United Airlines requested that the definition ofLPT overhaul change from 

"maintenance which involves disassembly of the LPT rotor module" to "when the LPT 

module is disassembled sufficiently to gain access to the LPT 4th stage rotor assembly 

(disk/blade/seal)." Delta Airlines requested that the definition of an LPT overhaul to be 

defined as "when all disks in the rotor are removed from the engine and the blades are 

removed." 

We agree that the definition of an LPT overhaul should be clarified. We changed 

the definition of an LPT overhaul to "An LPT overhaul is defined as when all disks in the 

rotor are removed from the engine and the blades are removed." 

Request to Change Applicability 

Delta Airlines requested changing the applicability to include models with any 

dash number suffix. 

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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. We determined that these changes will not increase the 

economic burden on any operator or increase the scope of this AD. 

Costs of Compliance 

We estimate that this AD affects 72 engines installed on airplanes ofU.S. registry. 

We also estimate that 9 of the engines will require replacement parts during shop visit, 

the pro-rated cost of these parts cost will be $23,805 per engine, and compliance with this 

AD will require about 49 hours oflabor per engine. The average labor rate is $85 per 

hour. We also estimate that 63 of the engines will require replacement parts during LPT 

overhaul, the prorated replacement parts cost for these parts is $43,545 per engine, and 

that these 63 engines will require 0 additional hours of labor per engine since the parts are 

already exposed during LPT overhaul. Based on these figures, we estimate the cost of this 

AD on U.S. operators to be $2.995.065. 

Authority for this Rulemaking 

Title 49 ofthe 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 

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Regulatory Findings 

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 to the extent that it justifies 

making a regulatory distinction, 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. 

Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the FAA 

amends 14 CFR part 39 as follows: 

PART 39- AIRWORTHINESS DIRECTIVES 

1. The authority citation for part 39 continues to read as follows: 

Authority: 49 U,S,C, 106(g), 40113, 4470L 

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No. FAA-2015-0787; Directorate Identifier 2015-NE-10-AD. 

(a) Effective Date 

This AD is effective [INSERT DATE 35 DAYS AFTER DATE OF 

PUBLICATION IN THE FEDERAL REGISTER]. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to: 

(I) All Pratt & Whitney Division PW4164, PW4168, PW4168A, PW4164C, 

PW4164C/B, PW4164-1D, PW4168-1D, PW4168A-1D, PW4170, PW4164C-1D, and 

PW4164C/B-1D turbofan engines with a low-pressure turbine (LPT) 4th stage inner air 

seal (lAS), part number (PIN) 51N038, installed. 

(2) All PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, 

PW4062A,PW4152,PW4156,PW4156A,PW4158,PW4160,PW4460,PW4462,and 

PW4650 turbofan engines including models with a "-3" suffix with an LPT 41h stage IAS, 

PIN 51N038, installed. 

(d) Unsafe Condition 

This AD was prompted by the discovery, during routine overhaul of the LPT, of 

cracks in the barrel section of the LPT 41h stage IAS which could, if not corrected, result 

in uncontained lAS release, damage to the engine, and damage to the aircraft. We are 

issuing this AD to prevent failure of the LPT 4th stage lAS, which could lead to an 

uncontained lAS release, damage to the engine, and damage to the airplane. 

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the LPT 4th stage !AS, PIN 51N038. 

(2) At each engine shop visit after the effective date of this AD, remove from 

service the LPT 4th stage lAS, PIN 51N038, if it has more than 10,900 cycles since new. 

(f) Installation prohibition 

(!)Do not install any LPT 4th stage !AS, PIN 51N038, with more than 0 flight 

cycles on any engine listed in paragraph ( c )(1) of this AD. 

(2) Do not install on any engine listed in paragraphs (c)(2) of this AD, any LPT 

41h stage lAS, PIN 51N038, which was previously installed on any engine listed in 

paragraph (c)(!) of this AD. 

(g) Definitions 

For the purposes of this AD: 

(1) An LPT overhaul is defined as when all disks in the rotor are removed from 

the engine and the blades are removed. 

(2) An "engine shop visit" is the induction of an engine into the shop for 

maintenance involving the separation of pairs of major mating engine flanges (lettered 

flanges). The separation of engine flanges solely for the purpose of transportation without 

subsequent engine maintenance does not constitute an engine shop visit. 

(h) Alternative Methods of Compliance (AMOCs) 

The Manager, Engine Certification Office, FAA, may approve AMOCs for this 

AD. Use the procedures found in 14 CFR 39.19 to make your request. You may email 

your request to: ANE-AD-AMOC@faa.gov. 

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Issued in Burlington, Massachusetts, on October 21, 2015. 

Colleen M. D' Alessandro, 

Directorate Manager, Engine & Propeller Directorate, 

Aircraft Certification Service. 

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