E9-14807. Airworthiness Directives; General Electric Company GE90-110B1, GE90-113B, and GE90-115B Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for General Electric Company (GE) GE90-110B1, GE90-113B, and GE90-115B series turbofan engines with stage 6 low-pressure turbine (LPT) blades, part number (P/N) 1765M37P03 or P/N 1765M37P04, installed. This proposed AD would require initial and repetitive inspections for shroud interlock wear of the stage 6 LPT blades. This proposed AD would also require replacing those blades with stage 6 LPT blades eligible for installation at the next engine shop visit as terminating action to the repetitive blade inspections. This proposed AD results from eight reports of GE90-115B stage 6 LPT single-blade separation events. We are proposing this AD to prevent failure of stage 6 LPT blades, which could result in uncontained engine failure and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by August 24, 2009.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD.

• Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: [phone].

Contact General Electric Company via GE—Aviation, Attn: Distributions, 111 Merchant St., Room 230, Cincinnati, Ohio 45246; telephone [phone]; fax [phone], for a copy of the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Barbara Caufield, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2009-0143; Directorate Identifier 2009-NE-05-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light 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 with FAA personnel concerning this proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Operations office 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 Operations office (telephone [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

Since December of 2007, GE reported eight instances of stage 6 LPT single-blade failures in some GE90 series engines. GE's investigation indicated that excessive wear at the shroud interlock of stage 6 LPT blades, P/N 1765M37P03 or P/N 1765M37P04, caused the failures. The interlock surface wears during operation which results in a loss of axial preload (contact between two surfaces) between two adjacent stage 6 LPT blades. This wear leads to increased tip deflection and blade stress. This condition, if not corrected, could result in failure of stage 6 LPT blades, which could result in uncontained engine failure and damage to the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of GE Service Bulletin No. GE90-100 SB 72-0260, Revision 6, dated May 1, 2009. That SB describes procedures for inspecting stage 6 LPT blades, P/N 1765M37P03, and P/N 1765M37P04, for shroud interlock wear.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which would require initial and repetitive inspections for shroud interlock wear of stage 6 LPT blades, P/N 1765M37P03 and P/N 1765M37P04. This proposed AD would also require replacing those blades with stage 6 LPT blades eligible for installation, at the next engine shop visit, as terminating action to the repetitive blade inspections. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

We estimate that this proposed AD would affect four GE GE90 series engines installed on airplanes of U.S. registry. We also estimate that it would take about 18 work-hours per engine to perform one inspection of the stage 6 LPT blades, and that the average labor rate is $80 per work-hour. Replacement stage 6 LPT blades would cost $258,280 per engine. We estimate that no additional labor costs would be incurred to perform the required blade replacements, because the replacements would be done at the time of the engine shop visit. Based on these figures, we estimate the total cost of the proposed AD for one inspection to U.S. operators to be $1,038,880.

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 have 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 that the proposed AD:

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); and

3. Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. You may get a copy of this summary at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Under the authority delegated to me by the Administrator, the Federal Aviation Administration 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:

General Electric Company: Docket No. FAA-2009-0143; Directorate Identifier 2009-NE-05-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by August 24, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) GE90-110B1, GE90-113B, and GE90-115B series turbofan engines with stage 6 low-pressure turbine (LPT) blades, part number (P/N) 1765M37P03 or P/N 1765M37P04, installed. These engines are installed on, but not limited to, Boeing 777-200LR, 777-300ER, and 777 Freighter series airplanes.

Unsafe Condition

(d) This AD results from eight reports of GE90-115B stage 6 LPT single-blade separation events. We are issuing this AD to prevent failure of stage 6 LPT blades, which could result in uncontained engine failure and damage to the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

Inspections

(f) Before accumulating 3,000 engine operating hours time-since-new, or 400 engine cycles-since-new, whichever occurs first, inspect the stage 6 LPT blades, P/N 1765M37P03 or P/N 1765M37P04 for shroud interlock wear. Thereafter, reinspect within every 1,000 engine operating hours, or within 125 engine cycles-since-last inspection, whichever occurs first. Use paragraphs 3.A. through 3.A.(3)(g)(12) of the Accomplishment Instructions of GE Service Bulletin (SB) No. GE90-100 SB 72-0260, Revision 6, dated May 1, 2009, to do the inspections.

Terminating Action

(g) At the next engine shop visit, replace stage 6 LPT blades, P/N 1765M37P03 or P/N 1765M37P04, with stage 6 LPT blades eligible for installation as terminating action to the repetitive inspections required by this AD.

Installation Prohibition of Affected Stage 6 LPT Blades

(h) After the effective date of this AD, do not install any stage 6 LPT blades, P/N 1765M37P03 or P/N 1765M37P04, onto any engine.

Previous Credit

(i) An inspection performed before the effective date of this AD using GE SB No. GE90-100 SB 72-0260, Revision 4, dated October 8, 2008, or Revision 5, dated November 7, 2008, satisfies the initial inspection requirement of this AD.

Definition

(j) For the purpose of this AD, an engine shop visit is induction of the engine into the shop for any cause.

Alternative Methods of Compliance

(k) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.

Related Information

(l) Contact Barbara Caufield, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone], for more information about this AD.

(m) Guidance on stage 6 LPT blades that are eligible for installation can be found in GE Service Bulletin No. 72-0279, Revision 1, dated December 11, 2008, and GE Service Bulletin No. 72-0313, dated March 18, 2009.

(n) Contact General Electric Company via GE—Aviation, Attn: Distributions, 111 Merchant St., Room 230, Cincinnati, Ohio 45246; telephone [phone]; fax [phone], for a copy of the service information identified in this AD.

Issued in Burlington, Massachusetts, on June 17, 2009.

Carlos Pestana,

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