[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

[[Page 47448]]

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