[Federal Register Volume 64, Number 168 (Tuesday, August 31, 1999)]
[Proposed Rules]
[Pages 47447-47449]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-22562]
[[Page 47447]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-ANE-16]
RIN 2120-AA64
Airworthiness Directives; Rolls-Royce, plc. RB211 Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Rolls-Royce, plc.
(R-R) RB211 series turbofan engines, that currently requires removing
from service intermediate pressure (IP) compressor stage 6-7 rotor
shafts that exceed reduced cyclic life limits. This action would
further reduce cyclic life limits and introduce new reduced cyclic
bands for rework. This proposal is prompted by additional stress
analysis conducted following failure of an IP compressor stage 6 disk.
The actions specified by the proposed AD are intended to prevent an
uncontained engine failure due to rupture of an IP compressor stage 6-7
rotor shaft.
DATES: Comments must be received by November 1, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 94-ANE-16, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``9-ane-
[email protected]''. 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, P.O.
Box 31, Derby, England. 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: Jason Yang, Aerospace Engineer, Engine
Certification Office, FAA, Engine and Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7747, 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 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 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 proposal must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-ANE-16.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
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. 94-ANE-16, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
On September 1, 1994, the Federal Aviation Administration (FAA)
issued airworthiness directive (AD) 94-18-03, Amendment 39-9016 (59 FR
46536, September 9, 1994), applicable to Rolls-Royce, plc (R-R) RB211-
22B and -524 series turbofan engines, to require removing from service
intermediate pressure (IP) compressor stage 6-7 rotor shafts that
exceed reduced cyclic life limits. That action was prompted by
information from the Civil Aviation Authority (CAA) of the United
Kingdom (UK), which advised the Federal Aviation Administration (FAA)
that they received a report of an uncontained failure of an IP
compressor stage 6-7 rotor shaft installed in an R-R RB211-22B engine
that failed during takeoff roll. Investigation determined that the
failure has been caused by a crack which emanated from a corrosion pit
and extended radially inward from the bolt holes to the rotor shaft
diaphragm. The manufacturer, R-R, determined that the rotor shaft would
not reach its published life limit without cracking under normal
operating conditions.
Since the issuance of that AD, R-R performed refined stress and
critical parts lifing analyses that revealed the cyclic life limits for
affected IP compressor stage 6-7 rotor shafts must be further reduced.
The affected rotor shafts include both reworked and non-reworked IP
compressor stage 6-7 rotor shafts. R-R also introduced a new rework
bands to rework the existing rotor shafts.
R-R has issued Service Bulletin (SB) No. RB.211-72-C538, dated
January 14, 1999, that specifies reduced cyclic life limits for IP
compressor stage 6-7 rotor shafts and reduced cyclic bands for rework.
To extend the life of the existing rotor shafts, R-R has issued SB
RB.211-72-9594, Revision 5, dated February 12, 1993, that specifies
rework of the IP compressor stage 6-7 rotor shaft when the cyclic life
falls within the rework bands described in the SB. Rework of the rotor
shafts includes machining out corrosion and creating new bolt holes
between the previous holes. The SB specifies a two-stage life reduction
for the affected rotor shafts, removing certain high cycle time disks
by the end of the calendar year 2000 prior to the removal of all disks
from the fleet by the end of calendar year 2001. The CAA classified SB
No. RB.211-72-C538 as mandatory and issued AD 003-01-99 in order to
assure the airworthiness of these engines in the UK.
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.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of the same type design, the
proposed AD would supersede AD 94-18-03 to specify reduced cyclic life
limits for IP
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compressor stage 6-7 rotor shafts and to introduce reduced cyclic bands
for rework. Rework of IP compressor stage 6-7 rotor shafts in
accordance with R-R SB No. RB.211 72-9594, or SB No. RB.211-72-9618
enables the parts to achieve their full, assigned cyclic life limits.
This AD is not applicable to those engines that incorporate new
intermediate pressure (IP) compressor stage 6-7 rotor shafts assemblies
with redesigned stage 6 disks in accordance with R-R SB No. RB.211-72-
9993, dated August 26, 1994.
Based on a risk analysis performed by the manufacturer, which
considers corrosion as one factor bearing on this condition, the AD
proposes a two-stage life reduction for the affected rotor shafts,
removing certain high cycle time disks by the end of the calendar year
2000, prior to the removal of all disks from the fleet by the end of
calendar year 2001.
There are approximately 1,300 engines of the affected design in the
worldwide fleet. The manufacturer has advised the FAA that there are
228 engines installed on aircraft of U.S. registry that would be
affected by this proposed AD. It would take approximately 24 work hours
or $1,440 per engine to accomplish the proposed rework actions, if
rework of the rotor shafts was selected. Otherwise, to maintain the
record of the cyclic life of IP compressor stage 6-7 rotor shafts has
minimum economic impact to U.S operators. Based on these figures, the
total cost impact of the proposed AD on U.S. operators is estimated to
be less than $330,000.
The regulations proposed herein would not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-9016 (59 FR
46536, September 9, 1994) and by adding a new airworthiness directive
to read as follows:
Rolls-Royce, plc: Docket No. 94-ANE-16. Supersedes AD 94-18-03,
Amendment 39-9016.
Applicability: Rolls-Royce plc (R-R) Model RB211-22B and -524
series turbofan engines, not incorporating new intermediate pressure
(IP) compressor stage 6-7 rotor shafts assemblies with redesigned
stage 6 disks in accordance with R-R Service Bulletin (SB) No.
RB.211-72-9993, dated August 26, 1994. These engines are installed
on but not limited to Boeing 747 series and 767 series, and Lockheed
L-1011 series aircraft.
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 (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: Required as indicated, unless accomplished
previously.
To prevent an uncontained engine failure due to rupture of an IP
compressor stage 6-7 rotor shaft, accomplish the following:
(a) For IP compressor stage 6-7 rotor shafts that have not been
reworked in accordance with SB RB.211-72-9594, Revision 8, dated
January 14, 1999, Revision 7, dated September 16, 1994, Revision 6,
dated August 12, 1994, or Revision 5, dated February 12, 1993,
remove the rotor shafts prior to exceeding the life limits
established in Table 1 of this AD under subtitle ``Pre SB 72-9594,''
and replace with serviceable parts.
Table 1
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Pre SB72-9594 Rework bands Post SB72-9594 Post SB72-9618
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Life Life Life Life Life Life Life Life Life
Engine mark and mod standard limits limits limits Rework Rework Rework limits limits limits limits limits limits
through after after bands bands after bands after through after after through after after
12/31/ 12/31/ 12/31/ through 12/ 12/31/00 12/31/01 12/31/ 12/31/ 12/31/ 12/31/ 12/31/ 12/31/
00 00 01 31/00 00 00 01 00 00 01
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RB.211-22B-02, Pre SB72-5787 and 11000 10000 9000 8000-11000 7500-10000 7500-9000 18000 17600 16600 N/A N/A N/A
Pre SB72-8700..................
RB.211-22B-02, Pre SB72-5787, 11000 10000 10000 8000-11000 7500-10000 7500-10000 17310 16960 15960 N/A N/A N/A
and Post SB72-8700.............
RB.211-22B-02, Post SB72-5787, 11000 11000 11000 8000-11000 8000-11000 8000-11000 18000 18000 18000 N/A N/A N/A
and Pre SB72-8700..............
RB.211-22B-02, Post SB72-5787 11000 11000 11000 8000-11000 8000-11000 8000-11000 17310 17310 17310 N/A N/A N/A
and Post SB72-8700.............
RB.211-524B-02, RB.211-524B3-02, 7500 7250 6250 6000-7500 4750-7250 4750-6250 13500 13500 12750 17500 17500 17500
RB.211-524B4-02, Pre SB72-5787.
RB.211-524B-02, RB.211-524B3-02, 8500 8200 7200 6500-8500 5700-8200 5700-7200 15000 14700 13700 19000 19000 18000
RB.211-524B4-02, Post SB72-5787
RB.211-524B-B-02, RB.211-524B4-D- 7500 7500 7400 6000-7500 6000-7500 5500-7400 13500 13500 13500 17500 17500 17500
02, Pre SB72-5787..............
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RB.211-524B--B02, RB.211-524B4-D- 8500 8200 7200 6500-8500 5700-8200 5700-7200 15000 14700 13700 19000 19000 18000
02, Post SB72-5787.............
RB.211-524B2, RB.211-524C2, 7500 7500 7300 6000-7500 6000-7500 5800-7300 13500 13500 13500 17500 17500 17500
RB211-524D4, RB211-524D4X, Pre
SB72-5787......................
RB.211-524B2, RB.211-524C2, 8500 8250 7250 6500-8500 5800-8250 5800-7250 15000 14500 13500 19000 18750 17750
RB211-524D4, RB211-524D4X, Post
SB72-5787......................
RB.211-524B2-B, RB.211-524C2-B, 7500 7500 7300 6000-7500 6000-7500 5800-7300 13500 13500 13500 17500 17500 17500
Pre SB72-5787..................
RB.211-524B2-B, RB.211-524C2-B, 8500 8200 7250 6500-8500 5800-8200 5800-7250 15000 14500 13500 19000 18650 17650
Post SB72-5787.................
RB.211-524D4-B, RB.211-524D4X-B, 8500 8500 7750 6500-8500 6500-8500 5750-7750 15000 15000 15000 19000 19000 19000
Post SB72-5787.................
RB.211-524G, RB.211-524G-T, 8500 8150 7150 6500-8500 5750-8150 5750-7150 13950 13950 13950 N/A N/A N/A
RB.211-524H, RB.211-524H-T,
Post SB72-5787.................
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(b) Remove from service IP stage 6-7 rotor shafts that have been
reworked in accordance with R-R SB RB.211-72-9594, Revision 8, dated
January 14, 1999, Revision 7, dated September 16, 1994, Revision 6,
dated August 12, 1994, or Revision 5, dated February 12, 1993, prior
to exceeding the new, reduced cyclic life listed in Table 1 of this
AD under the sub-title ``Post SB72-9594'' and replace with
serviceable part.
(c) Remove from service IP compressor stage 6-7 rotor shafts
that have been reworked in accordance with R-R SB RB.211-72-9618,
dated August 7, 1992, prior to exceeding the new, reduced cyclic
life limits listed in Table 1 of this AD under the sub-title ``Post
SB72-9618,'' and replace with serviceable parts.
(d) IP compressor stage 6-7 rotor shaft rework in accordance
with R-R SB RB.211-72-9594 can only be accomplished when the cyclic
life of the part falls within the rework bands established in the
Table 1 of this AD. To accomplish rework of IP compressor stage 6-7
rotor prior to reaching the lower limit of the rework bands
specified in the Table 1 of this AD, the part must be artificially
aged to the cyclic life which defines the lower limit of the
applicable rework bands in Table 1 of this AD.
Note 2: For example, if the lower limit of the rework band is
8,000 cycles, and the part is reworked at 7,000 cycles, the part
must be artificially aged by adding 1,000 cycles to the cycles since
new recorded on the part; i.e., on return to service the cycles
since new on this part would be 8,000 cycles.
(e) 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.
Operators shall submit their request through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, Engine Certification Office.
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.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the aircraft to a location where
the requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on August 25, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-22562 Filed 8-30-99; 8:45 am]
BILLING CODE 4910-13-U