Airworthiness Directives; Rolls-Royce, plc Tay 650-15 and 651-54 Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Rolls-Royce, plc Tay 650-15 and 651-54 turbofan engines. This proposal would require initial and repetitive visual and ultrasonic inspections of fan blades for cracks, and, if necessary, replacement with serviceable parts. In addition, this AD requires recording instances when engines are operated in a stabilized manner in newly prohibited ranges. This proposal is prompted by reports of fan blade failures. The actions specified by the proposed AD are intended to prevent fan blade failures, which can result in an uncontained engine failure, engine fire, and damage to the airplane.

DATES:

Comments must be received by November 13, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-68-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Rolls-Royce plc, Technical Publications Department, PO Box 31, Derby, England DE24 8BJ; telephone 44 1332 242424, fax 44 1332 249936. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Richard Woldan, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7136, fax (781) 238-7199.

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 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 notice 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 98-ANE-68-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. 98-ANE-68-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (UK), recently notified the Federal Aviation Administration (FAA) that an unsafe condition may exist on Rolls-Royce, plc (R-R) Tay 650-15 and 651-54 turbofan engines. The CAA advises that they have received a report of failure of five fan blades in the root section during takeoff which resulted in fan case punctures, severing of the low pressure (LP) fuel line and an extensive engine fire. Investigation revealed that fatigue cracks initiated in the fan blade root section due to fan resonance or flutter caused by the engine operating in a stabilized manner between idle reverse and emergency maximum reverse thrust (Tay 650-15) or maximum reverse thrust (Tay 651-54). The aircraft flight manuals have already been revised to prohibit operating in a stabilized manner within these ranges. However, inadvertent stabilized operations in the prohibited ranges could result in fan blade failure. This condition, if not corrected, could result in fan blade failure, which can result in an uncontained engine failure, engine fire, and damage to the aircraft.

Service Bulletins (SBs)

R-R has issued Service Bulletin (SB) No. Tay 72-1447, Revision 2, dated July 25, 2000, that specifies procedures for recording engine operation within the newly prohibited ranges, and SB No. Tay 72-1442, Revision 1, dated December 19, 1997, that describes procedures for inspection of fan blades. The CAA classified these SB's as mandatory in order to assure the airworthiness of these engines in the UK.

Bilateral Airworthiness Agreement

This engine model is manufactured in the UK and is type certificated for operation in the United States under the provisions of Section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design registered in the United States, the proposed AD would require initial and repetitive visual and ultrasonic inspections of fan blades for cracks, and, if necessary, replacement with serviceable parts. In addition, this AD would require recording instances when engines are operated in a stabilized manner in newly prohibited ranges. The actions would be required to be accomplished in accordance with the SB's described previously.

Economic Analysis

There are approximately 713 engines of the affected design in the worldwide fleet. The FAA estimates that 451 engines installed on airplanes of US registry would be affected by this proposed AD. Based on the current utilization and shop visit rates for the affected engine models, the FAA estimates that the number of shop visits and inspections for the US fleet would be approximately 140 per year. It would take approximately 5 work hours per engine to accomplish the proposed actions at a labor rate of $60 per work hour. Assuming that five percent of these inspections result in a rejected fan blade set at a cost of approximately $100,000 per set, the annual cost impact of the proposed AD on US operators is estimated to be $742,000. The current inspection failure rate is below one percent and this cost estimate is believed to be conservatively high.

Regulatory Impact

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.