Airworthiness Directives; Rolls-Royce plc Model RB211 Turbofan Engines

[Federal Register Volume 68, Number 95 (Friday, May 16, 2003)]
[Rules and Regulations]
[Pages 26481-26482]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-12109]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NE-12-AD; Amendment 39-13148; AD 2003-10-03]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce plc Model RB211 Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), that 
is applicable to Rolls-Royce plc (RR) model RB211-535E4-37, RB211-
535E4-B-37, and RB211-535E4-B-75 turbofan engines. This amendment 
requires removal from service of certain high pressure (HP) turbine 
discs before they reach newly established life limits. This amendment 
is prompted by the manufacturer's inspections and analysis of HP 
turbine discs that have accumulated high cycles. The actions specified 
by this AD are intended to prevent machining-induced cracking of the HP 
turbine disc which could cause an uncontained HP turbine disc failure 
and damage to the airplane.

DATES: Effective June 20, 2003.

ADDRESSES: Information regarding this action may be examined, by 
appointment, at the Federal Aviation Administration (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 (781) 238-
7178; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an AD that is 
applicable to RR model RB211-535E4-B-37 and RB211-535E4-B-75 turbofan 
engines was published in the Federal Register on November 6, 2002 (67 
FR 69160). That action proposed to require removal from service of 
certain HP turbine discs before they reach newly established life 
limits.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Change Explanation for Cracking

    One commenter states that the explanation for cracking in the HP 
disc rim cooling hole area is machining damage from new manufacture, 
and has nothing to do with the discs being sensitive to corrosion-
induced cracking, as stated in the proposal. The commenter also states 
that RR had previously indicated that the proposed life reduction was 
due to the condition described in RR Mandatory Service Bulletin (MSB) 
No. 72-C817. This MSB states that HP turbine discs part numbers (P/Ns) 
UL10323, UL27680, and UL27681 are sensitive to cracking in the disc rim 
cooling hole area due to machining damage from new manufacture.
    The FAA agrees. The cracking has been identified as occurring at 
the disc rim cooling hole area on the disc rear face. Although problems 
have been reported during overhaul, presumably due to rework or repair 
associated with, in part, corrosion, the primary explanation for this 
AD is machining damage. Therefore, in the final rule the explanation 
for cracking is changed to machining damage.

Clarification of Part Numbers

    One commenter requests that HP turbine discs P/Ns UL39766 and 
UL39767 be removed from the applicability and disc P/N UL10323 be 
added. The commenter states that disc P/N UL39766 is not listed in the 
RR Engine Illustrated Parts Catalogue or the Time Limits Manual. The 
commenter states that disc P/N UL39767 was introduced by RR Service 
Bulletin (SB) No. 72-C817 and is not subject to damage by machining. 
The commenter also states that disc P/N UL10323 is listed in the Time 
Limits Manual with a life limit of 14,800 cycles-since-new (CSN). 
Service Bulletin No. 72-C817 lists disc P/N UL10323, indicating that it 
is sensitive to cracking due to machining damage from manufacture.
    The FAA agrees. We determined that HP turbine disc P/N UL39766 was 
never produced by RR and is, therefore, removed from the final rule. 
Also, disc P/N UL39767 was introduced as a new part to replace disc P/N 
UL27681, and has, therefore, been removed from the final rule. Disc P/N 
UL10323 is affected by machining damage and is added to the final rule 
applicability with a life limit of 14,800 CSN.

Add Engine Model to Applicability

    One commenter asks if the RB211-535E4-37 engine should be included 
in the applicability.
    The FAA agrees that this AD should be applicable to engine model 
RB211-535E4-37. Therefore, this model is now listed in the final rule.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Economic Analysis

    There are approximately 400 RR model RB211-535E4-37, RB211-535E4-B-
37, and RB211-535E4-B-75 turbofan engines in the worldwide fleet 
containing the affected HP turbine discs, P/Ns UL10323, UL27680, and 
UL27681. 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 HP turbine discs P/Ns UL27680 and UL27681 from service before 
accumulating 15,000 cycles-since-new (CSN) and HP turbine discs P/N 
UL10323 from service before accumulating 14,800 CSN, rather than the 
former life limit of 20,000 CSN, is estimated to be $24,469,120.

Regulatory Analysis

    This final 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 final rule.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a

[[Page 26482]]

``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. A final 
evaluation has been prepared for this action and it 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.

Adoption of the Amendment

0
Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. Section 39.13 is amended by adding a new airworthiness directive to 
read as follows:

2003-10-03 Rolls-Royce plc: Amendment 39-13148. Docket No. 2002-NE-
12-AD.

    Applicability: This airworthiness directive (AD) is applicable 
to model RB211-535E4-37, RB211-535E4-B-37 and RB211-535E4-B-75 
turbofan engines with high pressure (HP) turbine disc, P/N UL10323, 
UL27680, and UL27681, installed. These engines are installed on, but 
not limited to Boeing 757 and Tupolev Tu204 airplanes.

    Note 1: This 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 (d) 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 machining-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 discs P/Ns UL27680 and UL27681 from 
service before accumulating 15,000 cycles-since-new (CSN).
    (b) Remove HP turbine discs P/N UL10323 from service before 
accumulating 14,800 CSN.
    (c) After the effective date of this AD, do not install any HP 
turbine disc P/N UL27680 or UL27681 that exceeds 15,000 CSN, or any 
HP turbine disc P/N UL10323 that exceeds 14,800 CSN.

Alternative Methods of Compliance

    (d) 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 Engine Certification Office.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
Sec. Sec.  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.

Effective Date

    (f) This amendment becomes effective on June 20, 2003.

    Issued in Burlington, Massachusetts, on May 9, 2003.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 03-12109 Filed 5-15-03; 8:45 am]
BILLING CODE 4910-13-P

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