2011-17622. Airworthiness Directives; Pratt & Whitney Corp. (PW) JT9D-7R4H1 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 all PW JT9D-7R4H1 turbofan engines. This proposed AD would require removing certain high-pressure compressor (HPC) shafts before their certified life limits, and establishes a new, lower life-limit for these parts. This proposed AD was prompted by reports of cracks in five HPC shafts. We are proposing this AD to correct the unsafe condition on these products.

DATES:

We must receive comments on this proposed AD by August 29, 2011.

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.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; 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:

Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, 12 New England Executive Park, Burlington, MA 01803; phone: [phone]; fax: [phone]; e-mail: [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-2011-0731; Directorate Identifier 2010-NE-39-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 received reports of five JT9D-7R4H1 engines containing an HPC shaft with cracks in the thread grooves of the rear shaft. These engines have the highest-thrust rating of the JT9D models, and were operating in hot environments. Higher operating metal temperatures impose a greater low-cycle fatigue life debit for each operating cycle, requiring removing the affected shafts before reaching their certified life limits. All of the cracked shafts were from the same fleet and engine model. This condition, if not corrected, could result in failure of the HPC shaft that could lead to an uncommanded in-flight shutdown or a possible uncontained engine failure and damage to the airplane.

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:

• For HPC shafts that have more than 4,500 cycles-since-new (CSN) on the effective date of this AD, removing the HPC shaft from service within 500 cycles-in-service (CIS) after the effective date of this proposed AD or at the next shop visit after the effective date of this proposed AD, whichever occurs first.
• For HPC shafts that have 4,500 or fewer CSN on the effective date of this AD, removing the HPC shaft from service before exceeding 5,000 CSN.

Costs of Compliance

We estimate that this proposed AD would not affect any engines installed on airplanes of U.S. registry.

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, 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
• 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):

Pratt & Whitney Corp: Docket No. FAA-2011-0731; Directorate Identifier 2010-NE-39-AD.

(a) Comments Due Date

We must receive comments by August 29, 2011.

(b) Affected ADs

None.

(c) Applicability

Pratt & Whitney Corp (PW) JT9D-7R4H1 turbofan engines with a high-pressure compressor (HPC) shaft, part numbers (P/Ns) 808070 or 808071, installed.

(d) Unsafe Condition

This AD was prompted by reports of cracks in five HPC shafts. We are issuing this AD to correct the unsafe condition on these products.

(e) Compliance

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

(f) Engines With an HPC Shaft, P/N 808071, That Has More Than 4,500 Cycles-Since-New (CSN)

For engines with an HPC shaft, P/N 808071, that has more than 4,500 CSN on the effective date of this AD, remove the HPC shaft from service within 500 cycles-in-service (CIS) after the effective date of the AD or at piece-part exposure, whichever occurs first.

(g) Engines With an HPC Shaft, P/N 808071, That Has 4,500 or Fewer CSN

For engines with an HPC shaft, P/N 808071, that has 4,500 or fewer CSN on the effective date of this AD, remove the HPC shaft from service before exceeding 5,000 CSN.

(h) Engines With an HPC Shaft, P/N 808070, Removal From Service

For engines with an HPC shaft, P/N 808070, remove the HPC shaft, P/N 808070, from service not later than 1,200 CSN.

(i) Installation Prohibition

After the effective date of this AD, do not install or reinstall into any engine:

(1) Any HPC shaft, P/N 808071, that is at piece-part exposure and exceeds the new lower life limit of 5,000 CSN, or

(2) Any HPC shaft, P/N 808070, that is at piece-part exposure and exceeds the new lower life limit of 1,200 CSN.

(j) Alternative Methods of Compliance (AMOCs)

The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19.

(k) Related Information

For more information about this AD, contact Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, 12 New England Executive Park, Burlington, MA 01803; phone: [phone]; fax: [phone]; e-mail: [e-mail].

Issued in Burlington, Massachusetts, on July 7, 2011.

Peter A. White,

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