[Federal Register Volume 65, Number 239 (Tuesday, December 12, 2000)]
[Proposed Rules]
[Pages 77528-77530]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-31613]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-27-AD]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce Corporation (Formerly 
Allison Engine Company) AE 2100 and AE 3007 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to adopt a new airworthiness directive 
(AD), applicable to Rolls-Royce Corporation, (formerly Allison Engine 
Company), AE 2100 and AE 3007 series engines. This proposed AD would 
require a one-time acid etch inspection of the 2nd stage high pressure 
turbine (HPT) wheel for cracks. If the wheel is cracked, this proposed 
AD would require replacement of the turbine wheel with a serviceable 
part. This proposed AD is prompted by a report of a 2nd stage turbine 
wheel that was returned from the field with cracks in the aft bore 
face. The actions specified by this proposed AD are intended to detect 
and prevent early development of cracks due to low cycle fatigue of the 
HPT 2nd stage wheel in the aft bore face that can lead to wheel 
failure, power loss, and possible damage to the airplane.

DATES: Comments must be received by February 12, 2001.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 2000-NE-27-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[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 a.m. and 4:30 
p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Michael Downs, Aerospace Engineer, 
Chicago Aircraft Certification Office,

[[Page 77529]]

FAA, Small Airplane Directorate, 2300 E. Devon Ave., Des Plaines, IL 
60018; telephone (847) 294-7870, fax (847) 294-7834.

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 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 2000-NE-27-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. 2000-NE-27-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received a report of 
cracks in the aft bore face of a 2nd stage high pressure turbine wheel 
from an AE 2100A engine that was returned from the field. Review of the 
manufacturing process revealed the cracks were caused by contact 
between the bore vertical face and a carbide tool bit during machining 
of the under side of the seal arm lip. This condition, if not 
corrected, could result in an early development of cracks due to low 
cycle fatigue of the HPT 2nd stage wheel in the aft bore face that can 
lead to wheel failure power loss, and possible damage to the airplane.
    The inspection intervals for the early manufactured turbine wheels 
(P/N 23050912) were set to maintain a risk of a wheel burst event to 
levels at or below 1x10 EE-8 events per cycle. This determination is 
made based on the crack growth rates observed in the one field returned 
turbine wheel, the specific missions flown for each engine model, and 
the probability of a turbine wheel having been damaged. The inspection 
interval for the remaining engine models was set at ``next shop visit'' 
based on the lower risk of having been damaged, the shot peen benefits, 
and the projected shop visit rate for these models.
    The ``one-time'' inspection is adequate because it identifies (via 
acid etch) those turbine wheels which were damaged during manufacturing 
and removes them from service thereby eliminating the risk of a 
premature wheel failure.

Service Bulletins (SB's)

    The FAA has reviewed and approved the technical contents of Rolls-
Royce Alert Service Bulletins (ASB's): AE2100A-A-72-234, Revision 2; 
AE2100C-A-72-183, Revision 2; AE2100D3-A-72-179, Revision, 2, dated 
October 17, 2000 and AE3007A-A-72, Revision 2, and AE3007C-A-72-153, 
Revision 2, dated October 17, 2000, that describe the procedures for 
examining the turbine wheels for damage using the one-time acid etch 
procedure.

Proposed Actions

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require a one-time acid etch inspection of the 2nd-
stage high pressure turbine wheel for damage. If the wheel is damaged, 
this proposal would require replacement of the turbine wheel with a 
serviceable part. The actions would be required to be done in 
accordance with the alert service bulletins described previously.

Economic Analysis

    There are approximately 1,376 engines of the affected design in the 
worldwide fleet. The FAA estimates that approximately 470 engines 
installed on airplanes of US registry would be affected by this 
proposed AD. The FAA estimates that disassembly to perform the acid 
etch inspection and reassembly will take approximately 130 work hours, 
which includes teardown to HPT, inspection and reassembly, and that the 
average labor rate is $60 per work hour. Labor costs to perform the 
disassembly/reassembly are $7,800, and a test stand run will cost about 
$5,000, for a total cost of $12,800 per engine to conduct the acid etch 
inspection. Based on these figures, the FAA estimates that the total 
cost impact of performing the acid etch inspection on US operators will 
be $6,016,000. If a wheel must be replaced, the cost of a replacement 
wheel is $18,000, and it will take an additional 30 work hours to 
replace the wheel, at $60 per work hour. Therefore the total cost of 
parts and labor for replacing the wheel will total $19,800.00 per 
wheel. If all wheels needed to be replaced, the total cost impact of 
the proposed AD on U.S. operators would be $15,322,000. The FAA 
estimates, however, that not all wheels will need replacement and that 
some labor costs required to accomplish the requirements of this 
proposed AD maybe reimbursed by the manufacturer, thus reducing the 
total cost impact of the proposed AD on US operators.

Regulatory Impact

    This proposal 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 proposal.
    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 Code of Federal Regulations (14 CFR part 39) as follows:

[[Page 77530]]

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 adding the following new 
airworthiness directive:

Rolls-Royce Corporation: Docket No. 2000-NE-27-AD.

    Applicability: This airworthiness directive is applicable to 
Rolls-Royce Corporation (formerly Allison Engine Company) models AE 
2100A and AE 2100C engines with high pressure turbine (HPT) wheel 
23050912 installed; AE 2100A engine with turbine wheel 23063462-
serial number (S/N) MM14062 installed; AE 2100D3 and AE 3007A, AE 
3007A1/1, AE 3007A1/2, AE 3007A1/3, AE 3007A1, AE 3007A1P, AE 3007A3 
and AE 3007C with HPT second stage wheels with S/Ns before MM183060. 
These engines are installed on but not limited to Embraer (EMB) 145 
and 135, Cessna Citation 750, and Industi Pesawat Terbang Nusantara 
(IPTN) N-250 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 (f) 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 the requirements of this AD is 
required as indicated, unless already.
    To detect and prevent early development of cracks due to low 
cycle fatigue of the high pressure turbine (HPT) 2nd stage wheel in 
the aft bore face that can lead to wheel failure power loss, and 
possible damage to the airplane, do the following:

One-time Inspection

    (a) Perform a one-time acid etch inspection to the 2nd stage 
high pressure turbine wheel in accordance with the Accomplishment 
Instructions contained in the following Rolls-Royce Alert Service 
Bulletins:

              Table 1.--Applicable Alert Service Bulletins
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               AE models                   Rolls-Royce service bulletin
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AE 2100A...............................  AE 2100A-A-72-234, Revision 2,
                                          dated October 13, 2000.
AE2100C................................  AE 2100C-A-72-183, Revision 2,
                                          dated October 13, 2000.
AE2100D3...............................  AE 2100D3-A-72-179, Revision 2,
                                          dated October 13, 2000.
AE3007A................................  AE 3007A-A-72-179, Revision 2,
                                          dated October 17, 2000.
AE3007C................................  AE 3007C-A-72-153, Revision 2,
                                          dated October 17, 2000.
------------------------------------------------------------------------

    (b) Perform these inspections according to the following 
compliance times:

                  Table 2.--Inspection Compliance Times
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             Models               With turbine wheel       Mandatory
------------------------------------------------------------------------
(1) AE2100A, AE2100C............  23050912..........  Before 4800 cycles
                                                       since new (CSN).
(2) AE2100A.....................  23063462-S/N MM     Before 4800 CSN.
                                   14062.
(3) AE2100D3....................  23050912..........  Before 3200 CSN.
(4) All other AE2100A, AE2100C,   23069592,           Next shop visit.
 and AE2100D3.                     23063462,
                                   23064822,
                                   23070673,
                                   23065892,
                                   23069116,
                                   233064473,
                                   23064474,
                                   23068072 with S/
                                   N's MM183060 and
                                   before..
(5) All AE3007A, AE3007A1/1, AE   23063462,           Next shop visit.
 3007A1/2, AE 3007A1/3, AE         23065892,
 3007A1, AE3007A1P, AE3007A3,      23069116,
 and AE3007C series engines.       23069592,
                                   23069438, with S/
                                   N MM183060 and
                                   before..
------------------------------------------------------------------------

    (c) If cracks are discovered, replace the turbine wheel with a 
serviceable part.
    (d) The next shop visit is defined as whenever the engine is 
removed and sent to a maintenance center for inspection or repair.
    (e) A serviceable part is defined as any turbine wheel with a 
serial number greater than MM183060, or less than MM183060, that has 
undergone an acid etch inspection and has been determined to have no 
cracks.

Alternative Methods of Compliance

    (f) 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, Chicago Aircraft 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, Chicago Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Chicago Aircraft Certification 
Office.

Ferry Flights

    (g) Special flight permits may be issued in accordance with 
Secs. 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 December 1, 2000.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-31613 Filed 12-11-00; 8:45 am]
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