2015-24731. Airworthiness Directives; Engine Alliance Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Engine Alliance (EA) GP7270 turbofan engines. This proposed AD was prompted by the manufacturer informing us that the inspection and repair criteria in the maintenance manual for aft bolt holes of the high-pressure compressor (HPC) cone shaft on the affected engines is incorrect. This proposed AD would require inspection of the HPC cone shaft and repair of affected parts, if needed. We are proposing this AD to prevent failure of the HPC cone shaft, which could lead to uncontained engine failure and damage to the airplane.

DATES:

We must receive comments on this proposed AD by November 30, 2015.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• 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: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Engine Alliance, 400 Main St., East Hartford, CT 06108, M/S 169-10, phone: [phone]; email: [e-mail]; Web site: sp.engineallianceportal.com. 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.

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-2015-3585; 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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Martin Adler, Aerospace Engineer, Engine & Propeller Directorate, FAA, 12 New England Executive Park, Burlington, MA 01803; phone: [phone]; fax: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2015-3585; Directorate Identifier 2015-NE-22-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because 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 proposed AD.

Discussion

We learned from the manufacturer that the inspection criteria and the repair procedures for the aft bolt holes of the HPC cone shaft, also referred to as the “HPC forward stub shaft,” were listed incorrectly in the maintenance manual for the Engine Alliance GP7270 turbofan engines. HPC cone shafts inspected or repaired using the incorrect criteria in the maintenance manual could result in premature cracking of these parts. This condition, if not corrected, could result in failure of the HPC cone shaft, which could lead to uncontained engine failure and damage to the airplane.

Relevant Service Information Under 1 CFR Part 51

Engine Alliance has issued EA Service Bulletin (SB) No. EAGP7-72-329, dated July 21, 2015; and EA SB No. EAGP7-72-330, dated July 21, 2015. The SBs describe procedures for shotpeening and inspection of the HPC cone shaft. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section of this NPRM.

FAA's Determination

We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would require inspection of the HPC cone shaft and repair of affected parts, if needed.

Costs of Compliance

We estimate that this proposed AD affects zero engines installed on airplanes of U.S. registry. The average labor rate is $85 per hour. Based on these figures, we estimate the cost of this proposed AD on U.S. operators to be $0.

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 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 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

We determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under the 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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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):

Engine Alliance: Docket No. FAA-2015-3585; Directorate Identifier 2015-NE-22-AD.

(a) Comments Due Date

We must receive comments by November 30, 2015.

(b) Affected ADs

None.

(c) Applicability

This AD applies to Engine Alliance (EA) GP7270 turbofan engines with a high-pressure compressor (HPC) cone shaft, part number (P/N) 382-100-907-0, installed.

(d) Unsafe Condition

This AD was prompted by the manufacturer informing us that the inspection and repair criteria in the maintenance manual for aft bolt holes of the HPC cone shaft on the affected engines is incorrect. We are issuing this AD to prevent failure of the HPC cone shaft, which could lead to uncontained engine failure and damage to the airplane.

(e) Compliance

Comply with this AD within the compliance times specified, unless already done.

(1) For HPC cone shafts with serial numbers listed in EA Service Bulletin (SB) No. EAGP7-72-330, dated July 21, 2015, inspect the inner diameter of the HPC cone shaft aft bolt holes for nicks, dents, and scratches before accumulating 9,000 cycles since new (CSN). Do not reinstall the HPC cone shaft if the aft bolt hole has a nick, dent, or scratch that is greater than 0.002 inches in depth.

(2) For HPC cone shafts with serial numbers listed in EA SB No. EAGP7-72-329, dated July 21, 2015, shot peen the HPC cone shaft aft bolt holes before accumulating 9,000 CSN. Use paragraph 1 of the Accomplishment Instructions in EA SB No. EAGP7-72-329 to do the shotpeening.

(f) Installation Prohibition

After the effective date of this AD, do not install an HPC cone shaft onto an engine with the following:

(1) A nick, dent, or scratch in an HPC cone shaft aft bolt hole that is greater than 0.002 inches in depth; or

(2) any repair of an HPC cone shaft aft bolt hole that did not include shot peening.

(g) Alternative Methods of Compliance (AMOCs)

The Manager, Engine Certification Office, 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: [e-mail].

(h) Related Information

(1) For more information about this AD, contact Martin Adler, Aerospace Engineer, Engine & Propeller Directorate, FAA, 12 New England Executive Park, Burlington, MA 01803; phone: [phone]; fax: [phone]; email: [e-mail].

(2) EA SB No. EAGP7-72-329, dated July 21, 2015; and EA SB No. EAGP7-72-330, dated July 21, 2015, can be obtained from EA using the contact information in paragraph (h)(3) of this proposed AD.

(3) For service information identified in this AD, contact Engine Alliance, 400 Main St., East Hartford, CT 06108, M/S 169-10; phone: [phone]; email: [e-mail]; Web site: sp.engineallianceportal.com.

(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.

Issued in Burlington, Massachusetts, on September 24, 2015.

Colleen M. D'Alessandro,

Directorate Manager, Engine & Propeller Directorate, Aircraft Certification Service.