E8-3192. Airworthiness Directives; Rolls-Royce plc RB211 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 the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

High pressure (HP) turbine discs recently inspected in accordance with the Engine Manual have exhibited cracks in the disc rim. The discs have failed to meet the inspection acceptance criteria and have been returned to Rolls-Royce for engineering investigation. This investigation has concluded that the cracks have resulted from scores within the cooling air holes in the disc rim that could have been introduced during new part manufacture or during overhaul of the disc. The engineering investigation has concluded that if this cracking was undetected then it could result in uncontained disc failure and a potential unsafe condition for the aircraft.

We are proposing this AD to prevent uncontained disc failure, possibly resulting in damage to the airplane.

DATES:

We must receive comments on this proposed AD by March 24, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• 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].

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.

FOR FURTHER INFORMATION CONTACT:

Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, Engine and 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-2007-0078; Directorate Identifier 2007-NE-40-AD” in the subject line 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 based on 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

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued AD 2006-0180, dated June 26, 2006, for RB211-524 series engines, AD 2006-0181, dated June 26, 2006, for RB211-22B engines, and AD 2006-0182, dated June 28, 2006, for RB211-535 series engines, to correct the same unsafe condition for the specified products. The EASA ADs state:

HPT discs recently inspected in accordance with the Engine Manual have exhibited cracks in the disc rim. The discs have failed to meet the inspection acceptance criteria and have been returned to Rolls-Royce for engineering investigation. This investigation has concluded that the cracks have resulted from scores within the cooling air holes in the disc rim that could have been introduced during new part manufacture or during overhaul of the disc. The engineering investigation has concluded that if this cracking was undetected then it could result in uncontained disc failure and a potential unsafe condition for the aircraft.

You may obtain further information by examining the MCAI ADs in the AD docket.

Relevant Service Information

Rolls-Royce plc has issued Alert Service Bulletin No. RB.211-72-AE969, dated May 9, 2006. The actions described in this service information are intended to correct the unsafe condition identified in the MCAI ADs.

FAA's Determination and Requirements of This Proposed AD

These products have been approved by the United Kingdom (UK), and are approved for operation in the United States. Pursuant to our bilateral agreement with the UK, they have notified us of the unsafe condition described in the MCAI ADs, and service information referenced above. We are proposing this AD because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design. This proposed AD would require initial and repetitive eddy current inspections of HP turbine discs.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 506 products of U.S. registry. We also estimate that it would take about 4 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $161,920.

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); and

3. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

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):

Rolls-Royce plc: Docket No. FAA-2007-0078; Directorate Identifier 2007-NE-40-AD.

Comments Due Date

(a) We must receive comments by March 24, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Rolls-Royce plc (RR) models RB211-535E4 series, RB211-535E4-B series, RB211-535E4-C series, RB211-535C series, RB211-524 series, and RB211-22B series turbofan engines. These engines are installed on, but not limited to, Boeing 747, 757, and 767, Lockheed L-1011, and Tupulev Tu204 airplanes.

Reason

(d) European Aviation Safety Agency AD 2006-0180, dated June 26, 2006, AD 2006-0181, dated June 26, 2006, and AD 2006-0182, dated June 28, 2006, state:

High pressure (HP) turbine discs recently inspected in accordance with the Engine Manual have exhibited cracks in the disc rim. The discs have failed to meet the inspection acceptance criteria and have been returned to Rolls-Royce for engineering investigation. This investigation has concluded that the cracks have resulted from scores within the cooling air holes in the disc rim that could have been introduced during new part manufacture or during overhaul of the disc. The engineering investigation has concluded that if this cracking was undetected then it could result in uncontained disc failure and a potential unsafe condition for the aircraft.

We are issuing this AD to prevent uncontained disc failure, possibly resulting in damage to the airplane.

Actions and Compliance

(e) Unless already done, perform an initial eddy current inspection (ECI) of the HP turbine disc air cooling holes. Information on ECI of HP turbine disc cooling holes can be found in RR Engine Overhaul Process Manual No. TSD594-J, Overhaul Process 223, dated May 1, 2001.

Initial Inspection for RB211-22B Series Turbofan Engines

(f) For RB211-22B series turbofan engines:

(1) If an installed HP turbine disc has more than 9,500 cycles-since-new (CSN) on the effective date of this AD, then ECI the HP turbine disc by whichever is the soonest of the following conditions:

(i) Within 500 cycles from the effective date of this AD; or

(ii) At the next shop visit where the HP turbine rotor is removed from the combustor outer casing.

(2) If an installed HP turbine disc has 9,500 or fewer CSN on the effective date of this AD, then ECI the HP turbine disc by whichever is the soonest of the following conditions:

(i) Before reaching 10,000 CSN; or

(ii) At the next shop visit where the HP turbine rotor is removed from the combustor outer casing and the HP turbine disc has more than 2,750 CSN.

(3) For HP turbine rotors at shop visit and already removed from the combustor outer casing on the effective date of this AD, ECI the HP turbine disc before reinstalling the HP turbine rotor in the combustor outer casing.

Initial Inspection of RB211-524 Series Turbofan Engines

(g) For RB211-524 series turbofan engines, ECI the HP turbine disc at the soonest of the following after the effective date of the AD:

(1) At the next shop visit where the HP turbine blades are removed from the HP turbine disc and when the HP turbine disc has more than 2,750 CSN.

(2) For HP turbine rotors at shop visit and the HP turbine blades are removed from the HP turbine disc and the HP turbine disc life is more than 2,750 CSN, ECI the turbine disc before reinstalling the HP turbine blades.

Initial Inspection of RB211-535C, -535E4, -535E4-B, and -535E4-C Series Turbofan Engines

(h) For RB211-535C, -535E4, -535E4-B, and -535E4-C series turbofan engines:

(1) If an installed HP turbine disc has 17,500 or fewer CSN on the effective date of this AD, then ECI the HP turbine disc by whichever is the soonest of the following conditions:

(i) Before reaching 18,000 CSN; or

(ii) At the next shop visit where the HP turbine rotor is removed from the combustor outer casing, and the HP turbine disc has 5,000 or more CSN.

(iii) For HP turbine rotors at shop visit on the effective date of this AD that are removed from the combustor outer casing, and that have HP turbine discs with 5,000 or more CSN, ECI the HP turbine disc before reinstalling the HP turbine rotor in the combustor outer casing.

(2) If an installed HP turbine disc has more than 17,500 CSN on the effective date of this AD, then ECI the HP turbine disc by whichever is the soonest of the following conditions:

(i) Within 500 cycles from the effective date of this AD; or

(ii) At the next shop visit where the HP turbine rotor is removed from the combustor outer casing.

(iii) For HP turbine rotors at shop visit on the effective date of this AD that are removed from the combustor outer casing, ECI the HP turbine disc before reinstalling the HP turbine rotor in the combustor outer casing.

HP Turbine Disc Permanent Etching

(i) On successful completion of the initial inspection only, permanently etch NMSB 72-AE969 onto the HP turbine disc, adjacent to the part number.

Repetitive ECI Inspections

(j) Thereafter, perform repetitive ECIs at every shop visit where the HP turbine blades are removed from the HP turbine disc. Information on ECI of HP turbine disc air cooling holes can be found in RR Engine Overhaul Process Manual No. TSD594-J, Overhaul Process 223, dated May 1, 2001.

(k) 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.

Previous Credit

(l) Initial inspections done before the effective date of this AD on HP turbine discs with a disc life above the minimum threshold (5,000 CSN for the RB211-535 engines and 2,750 CSN for both the RB211-524 and the RB211-22B engines) at the time of inspection, per paragraph 1.C.(2) of RR Alert Service Bulletin No. RB.211-72-AE969, comply with the initial inspection requirements specified in this AD.

Related Information

(m) Refer to EASA AD 2006-0180, dated June 26, 2006, AD 2006-0181, dated June 26, 2006, and AD 2006-0182, dated June 28, 2006, for related information.

(n) Contact Ian Dargin, 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.

Issued in Burlington, Massachusetts, on February 13, 2008.

Peter A. White,

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