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**DEPARTMENT OF TRANSPORTATION Federal Aviation Administration**  **14 CFR Part 39 [Docket No. FAA** **- 20**  **15 -**  **0266 ; Directorate Identifier**  **20 15**  **- NE**  **- 03**  **- AD; Amendment**  **39 -**  **18 185**  **; AD 2015**  **- 12**  **- 10**  **] RIN 2120**  **- AA64**  **Airworthiness Directives; Pratt & Whitney**  **Division Tur** **bofan Engines AGENCY:**  Federal Aviation Administration (FAA), DOT. **ACTION:** Final rule; request for comments. **SUMMARY:** We are adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW6122A and PW6124A turbofan engines. This AD requires initial and repetitive borescope inspection s (BSI s ) of the high - pressure compressor (HPC) 7 th stage int egrall y bladed (IB) rotor aft integral arm for cracks until replacement of the HPC 7 th stage IB rotor using non - silver - plated nuts . This AD was prompted by reports of crack finds in the HPC 7 th stage IB rotor . We are issuing this AD to prevent HPC 7 th stage IB rotor fracture s , which could lead to uncontained engine failure and damage to the airplane. **DATES:** This AD is effective [ IN SERT DATE 15 DAYS AF TER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. The Director of the Federal Register approved the incorporation by reference of certain publication s listed in this AD as of [ IN SERT DATE 15 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. We must receive comments on this AD by [ INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGI STER]. **ADDRESSES:** You may send comments , using the procedures found in 14 CFR 11.43 and 11.45, b y any of the following methods:2 • Federal eRulemaking Portal: G o to http://www.regulations.gov . Follow the instructions for submitting comments. • Fax: 202 - 493 - 2251. • Mail: U.S. Department of Transportation, Docket Operations, M - 30, West Building Ground Floor, Room W12 - 140, 1200 New Jersey Avenue SE., Washington, DC 20590 . • Hand Delivery : U.S. Department of Transportation, Docket Operations, M - 30, West Building Ground Floor, Room W12 - 140, 1200 New Jersey Avenue SE., Washington, DC 20590 , between 9 a.m. and 5 p.m., Monday through Friday , except Federal holidays . For s ervice information identified in this AD, contact Pratt & Whitney , 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 Directorate, 12 New England Executive Par

k, Burlington, MA. For information on the availability of this material at the FAA, call 781 - 238 - 7125. Itis also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA - 2015 - 0266 . **Examining the AD Docket** You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA - 20 15 - 0266 ; 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 street address for the Docket Office (phone : 800 - 647 - 5527) is in the ADDRESSES section. C omments will be available in the AD docket shortly

after receipt. **FOR FURTHER INFORMATION CONTACT:** Wego Wang, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England3

Executive Park, Burlington, MA 01803; phone: 781 - 238 - 7134; fax: 781 - 238 - 7199; email: wego.wang@faa.gov. **SUPPLEM ENTARY INFORMATION:**  **Discussion** We received reports of crack s in the PW6122A and the PW6124A HPC 7 th stage IB rotor aft integral arm . The root cause is the presence of silver- plated nuts reacting with hot titanium in a high sulfur/high chlorine environment. This AD require s initial and repetitive BS Is of the HPC 7 th stage IB rotor . This AD also requires, as terminating action, replacement of the HPC 7 th stage IB rotor and HPC 7 th stage IB rotor silver- plated nuts with non - silver-plated nuts. This condition, if not corrected, could result in HPC 7 th stage IB rotor fracture s . We are issuing this AD to prevent HPC 7 th stage IB rotor fracture s , which could lead to uncontained engine failure and damage to the airplane. **Related Service Information under 1 CFR Part 51**  We reviewed PW Engineering Authorization (EA) No. 1 5 MM0 08 , Revision A, dated March 24, 2015 . We also reviewed PW Service Bulletin (SB) No. PW6ENG 72 - 4 6, dated March 5, 2015. Th e EA describe s procedures for BS Is of the HPC 7 th stage IB rotor aft integral arm for crack s using the split - case method . The SB describes removal and replacement of the HPC 7 th stage IB rotor , removal of the HPC 7 th stage IB rotor silver plated nuts, and the installation of non - silver plated nuts. This service information is reaso nabl y available because the interested parties have access to it through their normal course of business or b y the means identified in the ADDRESSES section of this AD. **FAA’s Determination** We are issuing this AD because we evaluated all the relevant inform ation and determined the unsafe condition described previously is likely to exist or develop in other products of the same typ e design .4

**AD Requirements** This AD requires initial and repetitive BS Is of the HPC 7 th stage IB rotor . This AD also requires as ter

minating action to replace the HPC 7 th stage IB rotor and HPC 7 th stage IB rotor silver-plated nuts with non - silver- plated nuts. **FAA’s Justification and Determination of the Effective Date** No domestic operators use this product. Therefore, we find that notice and opportunity

for prior public comment are unnecessary and that good cause exists for making this amendment effective in less than 30 days . **Comments Invited** This AD is a final rule that involves requirements affecting flight safety and was not preced ed b y notice and an opportunity for public comment. However, w e invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. In clude “Docket No. FAA - 2015 - 0266; Directorate Identifier 2015 -NE - 03 - AD” at the beginning of your comments. We specificall y invite comments on the overall regulatory , economic, environmental, and energy aspects of this AD . We will consider all comments received b y the closing date and may amend this AD bec ause of those comments. We will post all comments we receive, without change, to http://www.regulations.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this AD. **Co sts of Compliance**  We estimate that this AD will affect 0 engines installed on airplanes of U.S. registry . We also estimate that it would take about 8 hours per engine to comply with this AD. The average labor rate is $85 per hour. Based on these figures, w e estimate the total cost of this AD to U.S. operators to be $0.5

**Authority for this Rulemaking** Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA A dministrator. “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 th at 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. **Regulatory Findings** This AD will not have federalism implications under Executive Order 13132. This AD wil l 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 certif y 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 F R 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.6

**List of Subjects in 14 C FR Part 39**  Air transportation , Aircraft, Aviation safety, Incorporation by reference, Safety. **Adoption of the Amendment** Accordingl y, 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 , 44701. **§ 39.13 [Amended]** 2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD): **2015 -**  **12 -**  **10 Pratt**  **& Whitney Divi**  **sion** : Amendment 39 - 18 185 ; Docket No. FAA - 20 15 - 0266 ; Directorate Identifier 20 15 - NE - 03 - AD . **(a) Effective Date**  This AD is effective [ IN SERT DATE 15 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER]. **(b) Affected ADs**  None. **(c) Applicability**  This AD appl ies to all Pratt & Whitney Division (PW) PW 6122A and PW 6124A turbofan engines with high -pressure compressor (HPC) 7 th stage integrally bladed (IB) rotor , part number (P/N) 5495637, installed. **( d**  **) Unsafe Condition**  This AD was prompted by reports of crack finds in the HPC 7 th stage IB rotor . We are issuing this AD to prevent HPC 7 th stage IB rotor fracture s , which could lead to uncontained engine failure and damage to the airplane.7

**( e** **) Compliance**  Comply with this AD within the compliance times specified, unle ss already done. (1) Within 180 cycles after the effective date of this AD or within 6 , 500 cycles accumulated on the HPC 7 th stage IB rotor , whichever occurs later , borescope inspect the HPC 7 th stage IB rotor for cracks. Use Appendix 1, paragraphs 5 and 6 of P W Engineering Authorization 15MM008, Revision A, dated March 24, 2015, to do your inspection. Thereafter, repeat the inspection at every 1 , 000 cycles since last inspection . (2) If any crack is detected on the HPC 7 th stage IB rotor , then before furth er flight, replace the HPC 7 th stage IB rotor with a part eligible for installation. **(f) Mandatory Terminating Action** (1) At the next shop visit after the effective date of this AD : (i) Replace the affected HPC 7 th stage IB rotor , P/N 5495637 , with a new, zero time, HPC 7 th stage IB rotor , P/N 5495637 , and ( ii ) Remove the HPC 7 th stage IB rotor silver- plated nuts , P/N 4301682 , and replace with non - silver-plated nuts . U se the A ccomplishment Instructions of PW Service Bulletin No. PW6ENG 72 - 46, dated March 5, 2015 to perform the removal and replacement. **( g** **) Definition**  For the purposes of this AD 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 . The separation of engine flanges solel y for the purposes of transportation without subsequent engine maintenance , is not 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 yo ur request to: ANE - AD - AMOC@faa.gov.8

**( i** **) Related Information**  For more information about this AD, contact Wego Wang, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propel ler Directorate, 12 New England Executive Park, Burlington, MA 01803; phone: 781 - 238 - 7134; fax: 781 - 238 - 7199; email: wego.wang@faa.gov. **( j**  **) Material Incorporated by Reference** (1) The Director of the Federal Register approved the incorporation b y reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Pratt & Whitney Divisio n (PW) Engineering Authorization No. 1 5 MM0 08 , Revision A, dated March 24, 2015 . (ii) PW S ervice B ulletin No. PW6ENG 72 - 46, dated March 5, 2015 . ( 3 ) For P W service information identified in this AD, contact Pratt & Whitney , 400 Main St., East Hartford, CT 0 6108; phone: 860 - 565 - 8770; fax: 860 - 565 - 4503 . (4 ) You may

view this service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA. For information on the availability

of this material at the FAA, call 781 - 238 - 7125. ( 5 ) You may

view this service information at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202 - 741 - 6030, or go to: http://www.archives.gov/federal - register/cfr/ibr locatio ns.html.9

Issued in Burlington, Massachusetts, on June 9 , 2015.

Ann C. Mollica , A cting Directorate Manager, Engine & Propeller Directorate, Aircraft Certification Service.