02-28954. Airworthiness Directives; Rolls-Royce plc Model RB211 Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to Rolls-Royce plc (RR) model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan engines. This proposal would require removal from service of certain high pressure (HP) turbine discs before they reach newly established life limits. This proposal is prompted by the manufacturer's inspections and analysis of HP turbine discs that have accumulated high cycles. The analysis reveals these discs to be sensitive to corrosion-induced cracking in the disc rim cooling hole area, which could result in uncontained HP disc failure. The actions specified by the proposed AD are intended to prevent corrosion-induced cracking of the HP turbine disc which could cause an uncontained HP turbine disc failure and damage to the airplane.

DATES:

Comments must be received by January 14, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-NE-12-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. Comments may also be sent via the Internet using the following address: “[e-mail]”. Comments sent via the Internet must contain the docket number in the subject line.

Information regarding this action may be examined, by appointment, at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Keith Mead, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299, telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2002-NE-12-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2002-NE-12-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The manufacturer has inspected and analyzed some HP turbine discs that have accumulated high cycles that were installed in model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan engines. The inspection and analysis reveals these discs to be sensitive to corrosion and crack propagation in the disc rim cooling hole area, which could result in uncontained HP turbine disc failure. The manufacturer has determined that the affected HP turbine discs are unable to achieve the previously published life limit of 20,000 cycles-since-new (CSN), due to the potential for corrosion-induced cracking to occur at or near that published life limit.

Proposed Requirements of This AD

Since an unsafe condition has been identified that is likely to exist or develop on other RR model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan engines of the same type design that are used on airplanes registered in the United States, the proposed AD would require removing from service HP turbine discs, P/N's UL27680, UL27681, UL39766, and UL39767 before reaching the new life limit of 15,000 CSN.

Economic Analysis

There are approximately 400 RR model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan engines in the worldwide fleet containing the affected HP turbine discs, P/N's UL27680, UL27681, UL39766, and UL39767. The FAA estimates that 346 engines installed on airplanes of U.S. registry will be affected by this AD, that it will take approximately 112 work hours per engine to replace an affected disc, and that the average labor rate is $60 per work hour. The FAA estimates that the prorated cost of the life reduction per engine would be approximately $64,000. Based on these figures, the total cost of the AD to remove from service the HP turbine discs at the new life limit of 15,000 CIS, rather than the former life limit of 20,000 CIS, is estimated to be $24,469,120.

Regulatory Analysis

This proposed rule does not have federalism implications, as defined in Executive Order 13132, because it 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposed rule.

For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new airworthiness directive:

Rolls-Royce plc: Docket No. 2002-NE-12-AD.

Applicability: This airworthiness directive (AD) is applicable to Rolls-Royce plc (RR) model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan engines with high pressure (HP) turbine disc, P/N UL27680, UL27681, UL39766, or UL39767 installed. These engines are installed on, but not limited to Boeing 757 and Tupolev Tu204 airplanes.

Note 1:

This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Compliance with this AD is required as indicated, unless already done. To prevent corrosion-induced cracking of the HP turbine disc which could cause an uncontained HP turbine disc failure and damage to the airplane, do the following:

(a) Remove HP turbine disc from service before accumulating 15,000 cycles-since-new (CSN).

(b) After the effective date of this AD, do not install any HP turbine disc listed in this AD that exceeds 15,000 CSN.

Alternative Methods of Compliance

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office (ECO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be done.

Issued in Burlington, Massachusetts, on November 6, 2002.

Francis A. Favara,

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