2011-26824. Airworthiness Directives; General Electric Company CF34-10E Series 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 General Electric Company (GE) CF34-10E series turbofan engines. This proposed AD was prompted by a report of heavy wear found on the seating surface of the center vent duct (CVD) (commonly referred to as center vent tube) support ring and on the inside diameter of the fan drive shaft at the mating location. This proposed AD would require removing from service CVD support assemblies from certain serial numbers (S/Ns) of CF34-10E series turbofan engines. This proposed AD would also require removing any fan drive shaft from service if wear is found on either the CVD support ring or the fan drive shaft. We are proposing this AD to prevent fan drive shaft failure, leading to uncontained engine failure and damage to the airplane.

DATES:

We must receive comments on this proposed AD by December 2, 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.

For service information identified in this AD, contact GE-Aviation, M/D Rm. 285, One Neumann Way, Cincinnati, OH 45215, phone: [phone]; e-mail: [e-mail]. 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;​; 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:

John Frost, 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-2011-0599; Directorate Identifier 2011-NE-19-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 a report of wear found on the seating surface of the CVD support ring and on the inside diameter of the fan drive shaft, where the two parts are in contact with each other. The wear was caused by relative motion between the CVD support assembly and the fan drive shaft during engine operation. The relative motion resulted from CVD support assemblies with improper sleeve thread lengths. This nonconformance was caused during manufacture, and the affected parts were released into service. A subpopulation of engines has been identified by engine S/N, that could have the same quality escape. Once removed, the CVD support assembly (consisting of self-locking nut, part number (P/N) 2226M57G03, threaded sleeve, P/N 2226M55P03, and support ring, P/N 2226M56P01) will be inspected for evidence of wear, and then never used again. This condition, if not corrected, could result in low-cycle-fatigue failure of the fan drive shaft, leading to engine failure.

FAA's Determination

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

Proposed AD Requirements

This proposed AD would require:

• First inspecting the seating surface of the CVD support ring for wear, and then inspecting the fan drive shaft inside diameter for wear, where the two parts come in contact with each other;
• If wear is found on either the CVD support ring seating surface or the corresponding contact area inside the fan drive shaft, then removing the fan drive shaft from service; and
• Removing from service all of the CVD support assemblies from the affected S/N engines identified in the proposed AD.

Costs of Compliance

We estimate that this proposed AD would affect 71 GE CF34-10E series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 8 work-hours per engine to perform a replacement of the CVD support assembly and visual inspections, and that the average labor rate is $85 per work-hour. A replacement CVD support assembly costs about $3,080. We estimate that two fan drive shafts would fail inspection and require replacement. A replacement fan drive shaft costs about $126,900. We estimate that no additional labor costs would be incurred to perform the required part replacements as the replacements are done at time of scheduled engine shop visit. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $520,760.

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
• 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):

General Electric Company: Docket No. FAA-2011-0599; Directorate Identifier 2011-NE-19-AD.

(a) Comments Due Date

We must receive comments by December 2, 2011.

(b) Affected ADs

None.

(c) Applicability

This AD applies to General Electric Company (GE) CF34-10E series turbofan engines, serial number (S/N) 994116, and S/Ns 994118 through 994186 inclusive.

(d) Unsafe Condition

This AD was prompted by a report of heavy wear found on the seating surface of the center vent duct (CVD) (commonly referred to as center vent tube) support ring and on the inside diameter of the fan drive shaft at the mating location. The wear is caused by relative motion between the CVD support assembly (consisting of self-locking nut, part number (P/N) 2226M57G03, threaded sleeve, P/N 2226M55P03, and support ring, P/N 2226M56P01) and the fan drive shaft, during engine operation. We are issuing this AD to prevent fan drive shaft failure, leading to uncontained engine failure and damage to the airplane.

(e) Compliance

Comply with this AD before accumulating 11,500 total cycles-in-service on the engine, unless already done.

(f) Inspection and Removal From Service of CVD Support Assembly; and Determination of Fan Drive Shaft Serviceability

Visually inspect the seating surface of the CVD support ring for wear.

(1) If there is sign of wear on the CVD support ring, remove the CVD support assembly and the fan drive shaft from service before further flight.

(2) If there is no sign of wear on the CVD support ring, remove the CVD support assembly from service and borescope inspect the inside diameter of the fan drive shaft at the CVD support ring contact area, for wear.

(3) If there is sign of wear on the fan drive shaft, remove the fan drive shaft from service before further flight.

(g) Installation Prohibition

After the effective date of this AD, do not return to service any CVD support assembly (consisting of self-locking nut, P/N 2226M57G03, threaded sleeve, P/N 2226M55P03, and support ring, P/N 2226M56P01) removed from service as specified in this AD.

(h) Definition

For the purposes of this AD, the phrase “any sign of wear” is defined as any visual indication of removal of parent material from the CVD seating surface or the fan drive shaft.

(i) 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.

(j) Related Information

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

(2) Refer to GE Service Bulletin No. CF34-10E S/B 72-0188, for related information. Contact GE-Aviation, M/D Rm. 285, One Neumann Way, Cincinnati, OH 45215, phone: [phone]; e-mail: [e-mail], for a copy of this service information. You may review copies of the referenced 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 October 6, 2011.

Peter A. White,

Manager, Engine & Propeller Directorate, Aircraft Certification Service.