03-7004. Airworthiness Directives; Rolls-Royce plc. RB211-535 Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), applicable to Rolls-Royce plc. (RR) models RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 turbofan engines, with certain part number (P/N) low pressure (LP) turbine stage 2 discs installed. That AD currently requires establishing new reduced LP turbine stage 2 disc cyclic limits. That AD also requires removing from service affected discs that already exceed the new reduced cyclic limit, and removing other affected discs before exceeding their cyclic limits, using a drawdown schedule. This proposal would require changing certain cyclic limits, changing the effective date of certain disc cyclic lives, and would allow intermix of Flight Plan A and Flight Plan B intermix calculations. This proposal is prompted by a reassessment of the thermal and stress data from recent operational experience and comments received from operators on the current AD. The actions specified by the proposed AD are intended to prevent LP turbine stage 2 disc failure, which could result in uncontained engine failure and possible loss of the airplane.

DATES:

Comments must be received by May 27, 2003.

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-16-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected, by appointment, at this location 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.

The service information referenced in the proposed rule may be obtained from Rolls-Royce plc, P.O. Box 31 Derby, DE24 8BJ, United Kingdom; telephone [phone]; fax [phone]. 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:

Ian Dargin, 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-16-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-16-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On November 8, 2002, the FAA issued AD 2002-23-08, Amendment 39-12952 (67 FR 71094, November 29, 2002), to require establishing new reduced LP turbine stage 2 disc cyclic limits, to require removing from service affected discs that already exceed the new reduced cyclic limit, and to remove other affected discs before exceeding their cyclic limits, using a drawdown schedule. The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (U.K.), had notified the FAA that an unsafe condition may exist on RR models RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 turbofan engines. The CAA advised that the manufacturer had performed a reassessment of the safe cyclic limits of LP turbine stage 2 discs, P/Ns UL11508, UL17141, UL18947, UL29029, and UL37352. The cyclic limits of these discs were reduced based on more recent thermal and stress data obtained from operational experience. This condition, if not corrected, could result in uncontained engine failure and possible loss of the airplane.

Since AD 2002-23-08 was issued, another reassessment of the thermal and stress data obtained through operational experience was made, and comments were received from operators on the current AD.

Comments

Interested persons have been afforded an opportunity to comment on final rule; request for comments AD 2002-23-08. Due consideration has been given to the comments received.

Request To Change Table 1 Life Limit

Two commenters request that the Flight Plan A life limit for item (1) December 31, 2001, listed in Table 1, be changed from 22,500 cycles-since-new (CSN) to the value of 23,200 CSN. The commenters state that the 22,500 CSN value does not agree with the corresponding table value in mandatory service bulletin (MSB) RB.211-72-D181, Revision 3, dated August 16, 2002.

The FAA agrees. We have changed item (1) of Table 1 of this proposed rule to 23,200 CSN.

Request To Change Effective Date of Disc Cyclic Life

Nine commenters request that the effective date of the disc cyclic life in Table 2 and Table 3 be changed from “On the effective date of this AD” to agree with the corresponding table value of “As of December 31, 2000” in MSB RB.211-72-D181, Revision 3, dated August 16, 2002.

The FAA agrees. We have changed the first columns of Table 2 and Table 3.

Request To Change Drawdown Schedule

Six commenters request the drawdown schedule in the AD be changed to coincide with the schedule in MSB RB.211-72-D181, Revision 3. The commenters have identified differences in various drawdown schedule cyclic limits between the AD and the MSB, and state the AD limits are more restrictive.

The FAA agrees. We have changed this proposed rule to coincide as much as possible with the drawdown schedule in the MSB.

Request for an Allowance for Flight Plan Intermix

One commenter states that the AD does not allow for Flight Plan A and Flight Plan B intermix count conditions and that this could result in a lower cyclic limit than required by the MSB.

The FAA agrees. We have incorporated the intermix note from the MSB into this proposed rule.

Request To Incorporate Four Tables from the MSB Versus the Three Tables in AD

One commenter states that the drawdown requirements and inspection were provided in four tables in MSB RB.211-72-D181, Revision 3, and that the AD should adopt the same tabular format. The commenter believes this would reduce the potential for confusion among the operators, eliminate contradiction between the MSB and AD, and ensure the original safety issues will be addressed.

The FAA partially agrees. It is unclear which four tables the commenter is referring to since they are not numbered in the MSB. However, in an effort to clarify this information, we have added additional levels of detail to Table 2 and Table 3.

Manufacturer's Service Information

Rolls-Royce plc. issued MSB RB.211-72-D181, Revision 3, dated August 16, 2002, that specifies a drawdown schedule for removing from service affected LP turbine stage 2 discs, using new Time Limits Manual (TLM) cyclic limits. This MSB provides a scheduled reduction, by engine and flight plan, of LP turbine stage 2 disc lives until the full life-cycle reduction on December 31, 2005.

This MSB also provides instructions for performing a one-time on-wing eddy current inspection for cracks of affected LP turbine stage 2 discs to allow a disc to remain in service for an additional 3,000 cycles, if it does not exceed the new, lower TLM cyclic limit. The CAA has classified this service bulletin as mandatory and issued AD 006-05-2001 in order to assure the airworthiness of these Rolls-Royce plc. turbofan engines in the U.K.

Bilateral Agreement Information

This engine model is manufactured in the U.K. 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 Requirements of This AD

Since an unsafe condition has been identified that is likely to exist or develop on other RR models RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 turbofan engines of the same type design, the proposed AD would require:

• Reducing the LP turbine stage 2 disc life-cyclic limits; AND
• Removing from service affected discs that already exceed the new reduced cyclic limits; AND
• Removing other affected discs before exceeding their cyclic limits, using a drawdown schedule.

The actions would be required to be done in accordance with the MSB described previously.

Economic Analysis

There are approximately 1,253 engines of the affected design in the worldwide fleet. The FAA estimates that 788 engines installed on airplanes of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 12 work hours per engine to perform each of the proposed inspections and 300 work hours per engine to perform the proposed disc removals. The average labor rate is $60 per work hour. Required parts would cost approximately $60,190 per engine. Based on these figures, the total cost of the proposed AD for performing one inspection per engine and removing all 788 discs, to U.S. operators is estimated to be $62,181,080.

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 removing Amendment 39-12952 (67 FR 71094, November 29, 2002), and by adding a new airworthiness directive, to read as follows:

Rolls-Royce plc.: Docket No. 2002-NE-16-AD. Supersedes AD 2002-23-08, Amendment 39-12952.

Applicability: This airworthiness directive (AD) is applicable to Rolls-Royce plc. (RR) models RB211-535E4-37, RB211-535E4-B-37, and RB211-535E4-B-75 turbofan engines, with low pressure (LP) turbine stage 2 discs part numbers (P/N's) UL11508, UL17141, UL18947, UL29029, and UL37352 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 (h) 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 LP turbine stage 2 disc failure, which could result in an uncontained engine failure and possible loss of the airplane, do the following:

Cycle Limits

(a) Change the RR Time Limits Manual cyclic limits for LP turbine stage 2 discs as specified in the following Table 1:

Table 1.—Time Limits Manual (TLM) Cyclic Limits

Date of reduced life limit	Life limits for RB211-535E4 engines operating in flight plan A, and RB211-535E4-B engines	Life limits for RB211-535E4 engines operating in flight plan B
(1) December 31, 2001	23,200 cycles-since new (CSN)	19,700 CSN.
(2) December 31, 2002	22,500 cycles-since-new (CSN)	19,000 CSN.
(3) December 31, 2003	21,500 CSN	18,000 CSN.
(4) December 31, 2004	20,000 CSN	16,500 CSN.
(5) December 31, 2005	18,100 CSN	14,600 CSN.

RB211-535E4 Engines Operating to Flight Plan A, and RB211-535E4-B Engines

(b) For RB211-535E4 engines operating to flight plan A, and RB211-535E4-B engines, remove the LP turbine stage 2 disc from service using the CSN and Action times listed in the following Table 2.

Table 2.—Drawdown Schedule for RB211-535E4 Engines Operating to Flight Plan A and RB211-535E4-B Engines

Disc CSN	Action	Replace disc
		Without eddy current inspection	With eddy current inspection
(1) 20,001 CSN or greater on December 31, 2000	Remove disc from service or perform optional on-wing eddy current disc inspection within 21 days after the effective date of this AD	Within 21 days after the effective date of this AD	Within 3,000 cycles-in-service (CIS) after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(2) 18,100 to 20,000 CSN on December 31, 2000	Remove disc from service or perform optional on-wing eddy current disc inspection	Before accumulating 21,000 CSN or within 21 days after the effective date of this AD, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(3) Fewer than 18,100 CSN on December 31, 2000 and greater than 20,000 CSN on December 31, 2004	Remove disc from service or perform optional on-wing eddy current disc inspection	Before accumulating 20,500 CSN or by December 31, 2004, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(4) Fewer than 18,100 CSN on December 31, 2000 and greater than 18,100 CSN on December 31, 2005	Remove disc from service or perform on-wing eddy current disc inspection	Before accumulating 20,000 CSN or by December 31, 2005, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(5) Fewer than 18,100 CSN on December 31, 2000 and fewer than 18,100 CSN on December 31, 2005	No action required	N/A.	N/A

(c) Information regarding disc removal may be found in 3.A. of the Accomplishment Instructions of Mandatory Service Bulletin (MSB) RB.211-72-D181, Revision 3, dated August 16, 2002.

(d) The optional on-wing eddy current disc inspection noted in Table 2 of this AD must be performed in accordance with 3.C.(1) through 3.C.(6) of the Accomplishment Instructions of MSB RB.211-72-D181, Revision 3, dated August 16, 2002.

RB211-535E4 Engines Operating to Flight Plan B

(e) For RB211-535E4 engines operating to flight plan B, remove the LP turbine stage 2 disc from service using the CSN and Action times listed in the following Table 3.

 Table 3.—Drawdown Schedule for RB211-535E4 Engines Operating to Flight Plan B

Disc CSN	Action	Replace disc
		Without eddy current inspection	With eddy current inspection
(1) 16,501 CSN or greater on December 31, 2000	Remove disc from service or perform optional on-wing eddy current disc inspection within 21 days after the effective date of this AD	Within 21 days after the effective date of this AD	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(2) Greater than 14,600 CSN on December 31, 2000	Remove disc from service or perform optional on-wing eddy current disc inspection	Before accumulating 17,500 CSN or within 21 days after the effective date of this AD, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(3) Fewer than 14,600 CSN on December 31, 2000 and greater than 16,500 CSN on December 31, 2004	Remove disc from service or perform optional on-wing eddy current disc inspection	Before accumulating 17,000 CSN or by December 31, 2004, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(4) Fewer than 14,600 CSN on December 31, 2000 and greater than 14,600 CSN on December 31, 2005	Remove disc from service or perform on-wing eddy current disc inspection	Before accumulating 16,500 CSN or by December 31, 2005, whichever occurs first	Within 3,000 CIS after the inspection, but do not exceed the new reduced life limit specified in Table 1 of this AD.
(5) Fewer than 14,600 CSN on December 31, 2000 and fewer than 14,600 CSN on December 31, 2005	No action required	NA	NA.

(f) Information regarding disc removal may be found in 3.A. of the Accomplishment Instructions of MSB RB.211-72-D181, Revision 3, dated August 16, 2002.

(g) The optional on-wing eddy current disc inspection must be performed in accordance with 3.C.(1) through 3.C.(6) of the Accomplishment Instructions of MSB RB.211-72-D181, Revision 3, dated August 16, 2002.

Note 2:

For engines moving from Flight Plans A to B or B to A, the intermix calculations found in MSB RB.211-72-D181, Revision 3, dated August 16, 2002, may be applied to the life limits.

Alternative Methods of Compliance

(h) 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, 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 3:

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

Special Flight Permits

(i) 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.

Note 4:

The subject of this AD is addressed in CAA airworthiness directive 006-05-2001, dated August 3, 2001.

Issued in Burlington, Massachusetts, on March 19, 2003.

Peter A. White,

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