Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
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.
Comments must be received by May 27, 2003.
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:
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 011–44–1332–242424; fax 011–44–1332–249936. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.
Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803–5299; telephone (781) 238–7178; fax (781) 238–7199.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
Air transportation, Aircraft, Aviation safety, Safety.
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:
1. The authority citation for part 39 continues to read as follows:
49 U.S.C. 106(g), 40113, 44701.
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:
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.
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:
(a) Change the RR Time Limits Manual cyclic limits for LP turbine stage 2 discs as specified in the following Table 1:
(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.
(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.
(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.
(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.
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.
(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
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).
(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.
The subject of this AD is addressed in CAA airworthiness directive 006–05–2001, dated August 3, 2001.