E9-17473. Airworthiness Directives; CFM International, S.A Model CFM56-3B1 and -3B2 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 certain CFM International Model CFM56-3B1 and -3B2 turbofan engines. This proposed AD would require initial and repetitive inspections for damage to the fan blades. This proposed AD results from a report of a failed fan blade with severe out-of-limit wear on the underside of the blade platform where it contacts the damper. We are proposing this AD to prevent failure of multiple fan blades, which could result in an uncontained failure of the engine and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by September 21, 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 CFM International, S. A., Technical Publication Department, 1 Neumann Way, Cincinnati, OH 45215; telephone [phone]; fax [phone], for a copy of the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Stephen K. Sheely, 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-2009-0606; Directorate Identifier 2009-NE-11-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

On February 13, 2006, we received a report of a failed fan blade with a 25 degrees midspan shroud. The underside of the blade platform had severe out-of-limit wear at a contact point with the damper. We couldn't determine the exact root cause for the wear. However, poor damping of the 25 degrees midspan shroud blade set due to severe wear on several dampers and the undersides of the fan blade platforms contributed to high dynamic stress levels seen on this set of blades. This condition, if not corrected, could result in failure of multiple fan blades, which could result in an uncontained failure of the engine and damage to the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of CFM International Service Bulletin (SB) CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007, that describes procedures for performing on-wing and in-shop inspections for wear.

Differences Between the Proposed AD and the Manufacturer's Service Information

CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007, requires an initial inspection within 6 months. This proposed AD would require the initial inspection within 3,000 cycles-in-service (CIS) after the effective date of the proposed AD. CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007, also requires a repetitive inspection within 1,500 to 3,000 cycles-since-last inspection (CSLI). This proposed AD would require the repetitive inspection within 3,000 CSLI.

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 performing initial and repetitive inspections of the fan blade for wear. 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 50 engines installed on airplanes of U.S. registry. We also estimate that it would take about 8 work-hours per engine to perform the proposed actions, and that the average labor rate is $80 per work-hour. Required parts would cost about $38,000 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $1,932,000.

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:

CFM International S.A.: Docket No. FAA-2009-0606; Directorate Identifier 2009-NE-11-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by September 21, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to CFM International S.A. model CFM56-3B1 and -3B2 turbofan engines with 25 degrees midspan shroud fan blades, part numbers (P/Ns) 9527M99P08, 9527M99P09, 9527M99P10, 9527M99P11, 1285M39P01, or fan blade pairs, P/Ns 335-088-901-0, 335-088-902-0, 335-088-903-0, and 335-088-904-0 installed. These engines are installed on, but not limited to, Boeing 737 series airplanes.

Unsafe Condition

(d) This AD results from a report of a failed fan blade with severe out-of-limit wear on the underside of the blade platform where it contacts the damper. We are issuing this AD to prevent failure of multiple fan blades, which could result in an uncontained failure of the engine 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.

Inspection for Wear

(f) Within 3,000 cycles-in-service after the effective date of this AD, perform an on-wing or in-shop inspection of the fan blade and damper for wear. Use paragraph 3. Accomplishment Instructions of CFM International Service Bulletin (SB) CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007.

(g) If you find wear, perform additional inspections as specified in paragraph 3. Accomplishment Instructions of CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007.

(h) Thereafter, within intervals not to exceed 3,000 cycles-since-last inspection, perform an on-wing or in-shop inspection for wear. Use paragraph 3. Accomplishment Instructions of CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007.

(i) If you find wear, perform additional inspections as specified in paragraph 3. Accomplishment Instructions of CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007.

Installation Prohibition

(j) After the effective date of this AD, don't install any 25 degrees midspan shroud fan blades, P/Ns 9527M99P08, 9527M99P09, 9527M99P10, 9527M99P11, 1285M39P01, or fan blade pairs, P/Ns 335-088-901-0, 335-088-902-0, 335-088-903-0, and 335-088-904-0, unless they have passed an inspection specified in paragraph 3. Accomplishment Instructions of CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007.

Optional Terminating Action

(k) Replacing the 25 degrees midspan shroud fan blade set with a 37 degrees midspan shroud fan blade set terminates the repetitive inspection requirements specified in paragraph (h) of this AD.

Alternative Methods of Compliance

(l) 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

(m) Contact Stephen K. Sheely, 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.

(n) CFM International SB CFM56-3/3B/3C S/B 72-1067, dated February 15, 2007, pertains to the subject of this AD. Contact CFM International, S. A., Technical Publication Department, 1 Neumann Way, Cincinnati, OH 45215; telephone [phone]; fax [phone], for a copy of this service information.

(o) EASA airworthiness directive 2009-0036, dated February 20, 2009, also addresses the subject of this AD.

Issued in Burlington, Massachusetts, on July 16, 2009.

Peter A. White,

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