E7-20923. Airworthiness Directives; Rolls-Royce plc RB211-524 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) provided by the aviation authority of the United Kingdom to identify and correct an unsafe condition on an aviation product. The MCAI states the following:

Recently an RB211 HP turbine disc has been found with a crack which had propagated further than expected from the risk model that was used to establish the original inspection.

We are proposing this AD to detect cracks that could cause the high pressure (HP) turbine disc to fail and result in uncontained failure of the engine.

DATES:

We must receive comments on this proposed AD by November 23, 2007.

ADDRESSES:

You may send comments by any of the following methods:

• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 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].

You can get the service information identified in this proposed AD from Rolls-Royce plc, P.O. Box 31, DERBY, DE24 8BJ, UK, telephone: [phone]; 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:

Jason Yang, 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 any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2007-0036; Directorate Identifier 2007-NE-22-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 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 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).

Discussion

The Civil Aviation Authority (CAA), which is the aviation authority for the United Kingdom, has issued United Kingdom Airworthiness Directive G-2006-0002, dated February 13, 2006, to correct an unsafe condition for the specified products. The CAA AD states:

A population of HP turbine discs that were manufactured between 1989-1999 and which were subject to possible machining anomalies, were believed to have an increased chance of suffering from cooling air hole cracking, compared to the general fleet population of HP turbine discs. As a result of this risk, Rolls-Royce issued Non-Modification Service Bulletin (NMSB) 72-C816, recommending in-service inspections of the subject discs.

Recently an RB211 HP turbine disc has been found with a crack which had propagated further than expected from the risk model that was used to establish the original inspection defined in the above NMSB; This has led to the need for a revision of the original inspection requirements.

An HP turbine disc fracture would be uncontained and create a potential unsafe condition. Accordingly, this AD introduces revised inspection requirements to reflect the increased risk of HP turbine disc cracking and potential disc fracture.

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

Relevant Service Information

RR has issued Service Bulletin RB.211-72-AE718, dated January 24, 2006. The actions described in this service information are intended to correct the unsafe condition identified in the CAA AD.

FAA's Determination and Requirements of This Proposed AD

This product has been approved by the aviation authority of the United Kingdom, and is approved for operation in the United States. Pursuant to our bilateral agreement with the United Kingdom, they have notified us of the unsafe condition described above. We are issuing this AD because we evaluated all the information provided by the CAA and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 72 engines installed on airplanes of U.S. registry. We also estimate that it would take about 10.0 work-hours per product to comply with this proposed AD, and that the average labor rate is $80 per work-hour. Required parts would cost about $15,000 per product. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $1,137,600. Our cost estimate is exclusive of possible warranty coverage.

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 AD:

Rolls-Royce plc: Docket No. FAA-2007-0036; Directorate Identifier 2007-NE-22-AD.

Comments Due Date

(a) We must receive comments by November 23, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Rolls-Royce (RR) RB211-524 series turbofan engines with certain high pressure (HP) turbine disks, specified by part number (P/N) and serial number (SN) listed in Table 1 of this AD, installed. These engines are installed on, but not limited to, Boeing 747 series and 767 series airplanes and Lockheed L1011 series airplanes.

Reason

(d) Recently an RB211 HP turbine disc has been found with a crack which had propagated further than expected from the risk model that was used to establish the original inspection defined in the above NMSB; This has led to the need for a revision of the original inspection requirements.

An HP turbine disc fracture would be uncontained and create a potential unsafe condition. Accordingly, this AD introduces revised inspection requirements to reflect the increased risk of HP turbine disc cracking and potential disc fracture.

Actions and Compliance

(e) Unless already done, do the following actions.

(f) Carry out the eddy current inspection as detailed in Section 3—Accomplishment Instructions of Rolls-Royce NMSB 72-AE718, dated January 24, 2006, in accordance with the following schedule:

(1) The HP disc serial numbers listed in table 1 are to be inspected as follows:

Table 1.—HP Disk Serial Numbers by Part Number

Part No.	Serial No.	Part No.	Serial No.
UL29473	LAQDY6043	UL29472	LQDY9125
UL29473	LAQDY6048	UL29472	LQDY9554
UL29473	LAQDY6079	UL29472	LQDY9582
UL29473	LDRCZ10057	UL29472	LQDY9895
UL29473	LDRCZ10264	UL29472	LQDY9910
UL29473	LDRCZ10415	UL29472	LQDY9947
UL29473	LDRCZ11402	UL29472	LQDY9960
UL29473	LDRCZ11425	UL24994	LQDY6777
UL29473	LDRCZ11497	UL24994	LQDY6792
UL29473	LDRCZ11663	UL24994	LQDY6859
UL29473	LDRCZ11679	UL24994	LQDY6860
UL29473	LDRCZ12301	UL24994	LQDY6866
UL29473	LDRCZ12308	UL24994	LQDY6869
UL29473	LDRCZ12316	UL24994	LQDY6934
UL29473	LDRCZ12319	UL24994	LQDY6946
UL29473	LQDY6957	UL24994	LQDY6963
UL29473	LQDY9075	UL23166	LQDY6745
UL29473	LQDY9084	UL23166	LQDY6846
UL29473	LQDY9557	UL23166	LQDY6848
UL29473	LQDY9906	UL23166	LQDY6954
UL29473	LQDY9956	FK24790	LDRCZ12492
UL29473	LQDY9970	FK24790	LDRCZ12694
UL29473	LQDY9985

(2) For all RB211-524 engine marks except RB211-524D4 variants:

(i) If the HP turbine disc cycles are greater than 6150 cycles since new on the effective date of this AD, inspect the HP turbine disc within 500 cycles after the effective date of this AD.

(ii) If the HP turbine disc cycles are less than 6150 cycles since new on the effective date of this AD, inspect the disc by whichever is the soonest of the conditions below:

(A) Prior to reaching 6650 cycles since new. The HP turbine disc life at inspection must be greater than 700 cycles since new.

(B) At next shop visit where the HP turbine rotor is removed from the Combustor Outer Case and the HP turbine disc life is greater than 700 cycles since new. If a HP turbine disc that meets these cyclic life criteria is currently at shop visit, and if, at the effective date of this Airworthiness Directive, it has not yet been reinstalled into the Combustion Outer Case, then the HP turbine disc must be inspected in accordance with the requirements of this Airworthiness Directive at the current shop visit.

(3) For all RB211-524D4 engine mark variants:

(i) If the HP turbine disc cycles are greater than 5000 cycles since new on the effective date of this AD, inspect the HP turbine disc within 500 cycles after the effective date of this AD.

(ii) If the HP turbine disc cycles were less than 5000 cycles since new on the effective date of this AD, inspect the HP turbine disc by whichever is the soonest of the conditions below:

(A) Prior to reaching 5500 cycles since new. The HP turbine disc life at inspection must be greater than 700 cycles since new.

(B) At the next shop visit where the HP turbine rotor is removed from the Combustor Outer Case and the HP turbine disc life is greater than 700 cycles since new. If a HP turbine disc that meets these cyclic life criteria is currently at shop visit, and if, at the effective date of this Airworthiness Directive, it has not yet been reinstalled into the Combustion Outer Case, then the HP turbine disc must be inspected in accordance with the requirements of this Airworthiness Directive at the current shop visit.

(4) For all other HP turbine discs specified in the Applicability of this Directive but not listed in Table 1 on page 2:

(i) Inspect the HP turbine disc at next shop visit where the HP turbine rotor is removed from the Combustor Outer Case and the HP turbine disc life is greater than 700 cycles since new. If a HP turbine disc that meets these cyclic life criteria is currently at shop visit, and if, at the effective date of this Airworthiness Directive, it has not yet been reinstalled into the Combustion Outer Case, then the HP turbine disc must be inspected in accordance with the requirements of this Airworthiness Directive at the current shop visit.

(ii) If a HP turbine disc has previously passed the inspection to Rolls-Royce NMSB 72-C816 or the focused inspection carried out in accordance with Rolls-Royce TS594-J Overhaul Process Manual Task 70-00-00-200-223 at greater than 700 cycles since new, then either of these inspections meets the requirements of this Airworthiness Directive.

FAA AD Differences

(g) Wherever the MCAI AD specifies 24 November 2005, this AD specifies the effective date of this AD.

Other FAA AD Provisions

(h) 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.

Related Information

(i) Refer to the Civil Aviation Authority Airworthiness Directive G-2006-0002, dated February 13, 2006, and RR Nonmandatory Service Bulletin RB.211-72-AE718, dated January 24, 2006, for related information.

(j) Contact Jason Yang, 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 October 17, 2007.

Peter A. White,

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