[Federal Register Volume 69, Number 126 (Thursday, July 1, 2004)]
[Proposed Rules]
[Pages 39877-39880]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-14945]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-18515; Directorate Identifier 2004-NE-12-AD]
RIN 2120-AA64


Airworthiness Directives; Rolls-Royce Corporation (Formerly 
Allison Engine Company, Allison Gas Turbine Division, and Detroit 
Diesel Allison) 250-B and 250-C Series Turbofan and Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for Rolls-Royce Corporation (RRC) 250-B and 250-C series turbofan and 
turboshaft engines with certain part numbers (PNs) of compressor 
adaptor couplings manufactured by Alcor Engine Company (Alcor), EXTEX 
Ltd. (EXTEX), RRC, and Superior Air Parts (SAP) installed. This 
proposed AD would require operators to remove from service affected 
compressor adaptor couplings. This proposed AD results from nine 
reports of engine shutdown caused by compressor adaptor coupling 
failure. We are proposing this AD to reduce the risk of failure of the 
compressor adaptor coupling and subsequent loss of all engine power.

DATES: We must receive any comments on this proposed AD by August 30, 
2004.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-001.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    You may examine the comments on this proposed AD in the AD docket 
on the Internet at http://dms.dot.gov.

[[Page 39878]]


FOR FURTHER INFORMATION CONTACT: Robert Baitoo, Aerospace Engineer, Los 
Angeles Aircraft Certification Office, FAA, Transport Airplane 
Directorate, 3960 Paramount Blvd., Lakewood, CA 90712-4137; telephone: 
(562) 627-5245, fax: (562) 627-5210, for questions about Alcor, EXTEX, 
or SAP compressor adaptor couplings; and John Tallarovic, Aerospace 
Engineer, Chicago Aircraft Certification Office, FAA, 2300 East Devon 
Avenue, Des Plaines, IL 60018-4696; telephone (847) 294-8180; fax (847) 
294-7834, for questions about RRC compressor adaptor couplings.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

    We have implemented new procedures for maintaining AD dockets 
electronically. As of May 17, 2004, we posted new AD actions on the DMS 
and assigned a DMS docket number. We track each action and assign a 
corresponding Directorate identifier. The DMS docket No. is in the form 
``Docket No. FAA-200X-XXXXX.'' Each DMS docket also lists the 
Directorate identifier (``Old Docket Number'') as a cross-reference for 
searching purposes.

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-18515; 
Directorate Identifier 2004-NE-12-AD'' in the subject line of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of the 
DMS Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78) or you 
may visit http://dms.dot.gov.
    We are reviewing the writing style we currently use in regulatory 
documents. We are interested in your comments on whether the style of 
this document is clear, and your suggestions to improve the clarity of 
our communications that affect you. You can get more information about 
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, any comments 
received and, any final disposition in person at the DMS Docket Offices 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the DMS receives them.

Discussion

    The FAA has received reports of nine RRC 250-B and 250-C series 
turbofan and turboshaft engines that have experienced failure of the 
compressor adaptor coupling in service. Each failure has resulted in 
total loss of engine power, with three of the events resulting in 
accidents. The engines are installed in mostly single-engine 
helicopters, along with several turboprop airplanes. Alcor, EXTEX, and 
SAP each independently manufactured compressor adaptor couplings, under 
Parts Manufacturer Approval (PMA) authority. RRC manufactured 
compressor adaptor couplings under type and production certificate 
authority.
    While the precise mechanism of coupling failure is still under 
investigation, enough evidence has been collected to conclude that the 
four individual part designs could have unsatisfactory rates of failure 
in service, and should be removed from service as recommended and 
substantiated by each individual part manufacturer.
    Each of the four manufacturers is responsible for its own 
independent component design, design substantiation, component 
manufacture, and development of a field management plan for its fleet. 
EXTEX is handling field management of affected couplings made by SAP, 
under an agreement between the two manufacturers.
    Compliance requirements in this proposed AD have been developed 
based on the FAA's consideration of those individual field management 
plans and corresponding substantiation. The condition described 
previously, if not corrected, could result in failure of the compressor 
adaptor coupling and subsequent loss of all engine power.
    With respect to the field management plans, design and production 
approval holders are expected to have a comprehensive understanding of 
the system that the component is installed in and the consequences of 
failure of that specific component design. Also, design and production 
approval holders are expected to effectively collect and review service 
data and assess risk to support continued operational safety of their 
components in service. The different manufacturers of compressor 
adaptor couplings have conducted their own independent data reviews and 
risk assessments, with varying outcomes. These varying outcomes have 
generated different compliance requirements in this proposed AD, for 
users of each manufacturer's compressor adaptor coupling.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information available from field 
reports and from the four manufacturers' safety assessments and have 
identified an unsafe condition that is likely to exist or develop in 
other RRC 250-B17, -B17B, -B17C, -B17D, -B17E, 250-C20, -C20B, -C20F, -
C20J, -C20S, and -C20W series turbofan and turboshaft engines that have 
any of the following compressor adaptor couplings installed:
     Alcor: P/Ns 23039791AL and 23039791AL-1/-2/-3.
     EXTEX: P/Ns A23039791, E23039791, E23039791-1/-2/-3, 
EH23039791, and EH23039791-1/-2/-3.
     RRC: P/Ns 23039791-1/-2/-3.
     SAP: P/N A23039791.
    We are proposing this AD, which would:
     Remove from service affected Alcor compressor adaptor 
couplings using the schedule specified in the compliance section of 
this proposed AD. The related Alcor safety assessment and 
recommendations are based on a significant number of service part 
inspections and engineering judgment.
     Remove from service affected EXTEX and SAP compressor 
adaptor couplings using the schedule specified in the compliance 
section of this proposed AD. The related EXTEX and SAP safety 
assessments and recommendations are based on a significant number of 
service part inspections and engineering judgment.
     Remove from service affected RRC compressor adaptor 
couplings using the schedule specified in the compliance section of 
this proposed AD. The related RRC safety assessment and recommendations 
are based on a significant number of service part inspections, 
component tests, and

[[Page 39879]]

manufacturing and overhaul assembly analysis, and engineering analysis.

Costs of Compliance

    There are about 9,000 RRC 250-B and 250-C series turbofan and 
turboshaft engines of the affected design in the worldwide fleet. We 
estimate that 6,000 engines installed on helicopters and airplanes of 
U.S. registry would be affected by this proposed AD. We also estimate 
that it would take about 3 work hours per engine to perform the 
proposed actions when done at time of rotor disassembly, and that the 
average labor rate is $65 per work hour. Required parts would cost 
about $1,601 per engine. Based on these figures, we estimate the total 
cost of the proposed AD to U.S. operators to be $10,776,000.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a summary of the costs to comply with this proposal and 
placed it in the AD Docket. You may get a copy of this summary at the 
address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration proposes to amend 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. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive:

Rolls-Royce Corporation (formerly Allison Engine Company, Allison 
Gas Turbine Division, and Detroit Diesel Allison): Docket No. FAA-
2004-18515; Directorate Identifier 2004-NE-12-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by August 30, 
2004.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Rolls-Royce Corporation (formerly Allison 
Engine Company, Allison Gas Turbine Division, and Detroit Diesel 
Allison) 250-B17, -B17B, -B17C, -B17D, -B17E, 250-C20, -C20B, -C20F, 
-C20J, -C20S, and -C20W series turbofan and turboshaft engines with 
the compressor adaptor couplings installed listed in the following 
Table 1:

             Table 1.--Affected Compressor Adaptor Couplings
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               Manufacturer                     Affected part numbers
------------------------------------------------------------------------
Alcor Engine Company (Alcor)                P/Ns 23039791AL; 23039791AL-
                                             1/-2/-3;
EXTEX Ltd. (EXTEX)........................  A23039791; E23039791;
                                             E23039791-1/-2/-3;
                                             EH23039791; EH23039791-1/-2/
                                             -3.
Rolls-Royce Corporation (RRC)               23039791-1/-2/-3
Superior Air Parts (SAP)..................  A23039791
------------------------------------------------------------------------

    These engines are installed on, but not limited to, the aircraft 
in the following Table 2:

                      Table 2.--Applicable Aircraft
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                               Helicopters
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Agusta Models
    A109, A109A, A109A II Bell Models
    206A, 207B, 206L Enstrom Models
    TH-28, 480, 480B Eurocopter France Models
    AS355E, AS355F, AS355F1, AS355F2
Eurocopter Deutschland Models
    BO-105C, BO-105S
MDHI Models
    369D, 369E, 369H, 369HM, 369HS, 369HE
Schweizer Model 269D
------------------------------------------------------------------------
                                Airplanes
------------------------------------------------------------------------
B-N Group Ltd. Model
    BN-2T
------------------------------------------------------------------------

Unsafe Condition

    (d) This AD results from nine reports of engine shutdown caused 
by compressor adaptor coupling failure.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.

Alcor Compressor Adaptor Couplings

    (f) Remove Alcor compressor adaptor couplings, P/Ns 23039791AL, 
23039791AL-1, -2, and -3 from service as follows:
    (1) For couplings with 600 or more operating hours-since-new as 
of the effective date of this AD, or the operating hours are unknown 
and cannot be determined, remove couplings from service at next 
access but not to exceed 50 additional operating hours.
    (2) For couplings with fewer than 600 operating hours-since-new 
on the effective date of this AD, remove couplings from service at 
next access but not to exceed 649 operating hours-since-new.

EXTEX and SAP Compressor Adaptor Couplings

    (g) Remove EXTEX and SAP compressor adaptor couplings, P/Ns 
A23039791, E23039791, E23039791-1, -2, and -3, EH23039791, and 
EH23039791-1, -2, and -3, from service as follows:
    (1) For couplings with operating hours that are unknown and 
cannot be determined, remove couplings from service at next access 
but not to exceed 50 additional operating hours.
    (2) For couplings with 600 or more operating hours-since-new as 
of the effective date of this AD, remove couplings from service at 
next access but not to exceed 100 additional operating hours.
    (3) For couplings with fewer than 600 operating hours-since-new 
on the effective date of this AD, remove couplings from service at 
next access but not to exceed 150 additional operating hours.

RRC Compressor Adaptor Couplings

    (h) Remove RRC compressor adaptor couplings, P/Ns 23039791-1, -
2, and -3 from service at next access but not later than March 1, 
2012.

Installation Requirements for Compressor Adaptor Couplings

    (i) Machine the compressor impeller as follows:
    (1) Machine the inside diameter (ID) to accept the next larger 
size outside diameter (OD) compressor adaptor coupling.
    (2) For example, if a -1 coupling was removed, a -2 coupling 
must be installed.
    (3) If a -3 coupling is removed, a new impeller is required.

[[Page 39880]]

    (4) A fit of 0.0000 to -0.0018 inch must be achieved. No 
fretting is allowed on the impeller after machining.
    (5) Due to previous fretting, an impeller with a -1 coupling 
removed might have to be machined for a -3 coupling. Plating of the 
impeller ID is not allowed.
    (6) Fluorescent penetrant inspect the impeller.
    (7) Install a new compressor adaptor coupling, P/N 23076559-2 or 
-3; or
    (8) If a new impeller is installed, then install compressor 
adaptor coupling, P/N 23076559-1.
    (9) Heating of the impeller per the engine overhaul manual is 
required to install the coupling to achieve the target fit specified 
in the following Table 3:

                                    Table 3.--Impeller-to-Coupling Target Fit
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             Impeller ID                     New Adaptor               Adaptor OD           Fit (Interference)
----------------------------------------------------------------------------------------------------------------
(i) 0.900 to 0.899 inch..............  23076559-1.............  0.9000 to 0.9008 inch..  0.0000 to -0.0018 inch.
(ii) 0.902 to 0.901 inch.............  23076559-2.............  0.9020 to 0.9028 inch..  0.0000 to -0.0018 inch.
(iii) 0.904 to 0.903 inch............  23076559-3.............  0.9040 to 0.9048 inch..  0.0000 to -0.0018 inch.
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Definition

    (j) For the purposes of this AD, next access is defined as when 
the compressor module is separated from the engine and disassembled 
for any reason.

Alternative Methods of Compliance

    (k) The Manager, Los Angeles Aircraft Certification Office, has 
the authority to approve alternative methods of compliance for 
Alcor, EXTEX, and SAP adaptor couplings addressed in this AD if 
requested using the procedures found in 14 CFR 39.19. The Manager, 
Chicago Aircraft Certification Office, has the authority to approve 
alternative methods of compliance for RRC adaptor couplings 
addressed in this AD if requested using the procedures found in 14 
CFR 39.19.

Material Incorporated by Reference

    (l) None.

Related Information

    (m) Alcor SLB No. 814-3-1, Revision C, dated April 28, 2004, 
EXTEX Alert Service Bulletin T-081, Revision B, dated May 4, 2004, 
and RRC CEB-A-1392 and CEB-A-1334, dated September 9, 2003, pertain 
to the subject of this AD.

    Issued in Burlington, Massachusetts, on June 25, 2004.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 04-14945 Filed 6-30-04; 8:45 am]
BILLING CODE 4910-13-P