[Federal Register Volume 71, Number 119 (Wednesday, June 21, 2006)]
[Rules and Regulations]
[Pages 35505-35507]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-5547]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-22594; Directorate Identifier 2005-NE-28-AD; 
Amendment 39-14659; AD 2006-13-06]
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 Turboprop and Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
Rolls-Royce Corporation 250-B and 250-C series turboprop and turboshaft 
engines with certain part numbers (P/Ns) of gas producer rotor assembly 
tie bolts manufactured by EXTEX Ltd., Pacific Sky Supply Inc., Rolls-
Royce Corporation (RRC), and Superior Air Parts Inc. This AD requires 
operators to remove from service affected gas producer rotor assembly 
tie bolts, and install serviceable tie bolts. This AD results from 
eleven reports of RRC tie bolt failure due to high cycle fatigue. We 
are issuing this AD to prevent tie bolt failure that could cause loss 
of engine power, resulting in a first stage turbine wheel overspeed and 
an uncontained engine failure.

DATES: This AD becomes effective July 26, 2006.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in Room PL-401 on the plaza level of the Nassif 
Building, 400 Seventh Street, SW., Washington, DC.

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, EXTEX Ltd., or Pacific Sky 
Supply Inc. gas producer rotor assembly tie bolts.
     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 gas producer rotor assembly tie bolts.
     Jurgen Priester, Aerospace Engineer, Rotorcraft 
Directorate, FAA, 2601 Meacham Blvd., Fort Worth, Texas 76137-4298, 
telephone (817) 222-5159, fax (817) 222-5785, for questions about 
Superior Air Parts Inc. gas producer rotor assembly tie bolts.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with a proposed AD. The proposed AD applies to Rolls-Royce Corporation 
250-B and 250-C series turboprop and turboshaft engines with certain P/
Ns of gas producer rotor assembly tie bolts manufactured by EXTEX Ltd., 
Pacific Sky Supply Inc., RRC, and Superior Air Parts Inc. We published 
the proposed AD in the Federal Register on November 10, 2005 (70 FR 
68381). That action proposed to require operators to remove from 
service affected gas producer rotor assembly tie bolts.

Examining the AD Docket

    You may examine the docket that contains the AD, any comments 
received, and any final disposition in person at the Docket Management 
Facility Docket Office 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.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Request To Exclude Parts Manufacturer Approval (PMA) Tie Bolts

    One commenter requests that the PMA tie bolts be excluded from the 
AD action, because there are no reported failures of the PMA tie bolts. 
Also, the commenter states that there are numerous opportunities for 
significant design differences between PMA tie bolts approved under 
Test and Computation, and the original equipment manufacturer (OEM) tie 
bolts.
    We do not agree. Although there are no reported failures of PMA 
parts, the tie bolts from all four manufacturers are essentially the 
same and share many common features. The fact that there are no 
reported failures of PMA parts is statistically insignificant since the 
PMA parts only account for several hundred of the approximately 5,000 
tie bolts in service, and there have been only 11 failures. 
Additionally, failures of a specific part number are not a prerequisite 
for declaring an unsafe condition. A failure mode's net result on the 
product (in this case loss of engine power, first stage turbine wheel 
overspeed, and an uncontained engine failure); the assumed or predicted 
rate of occurrence, and other factors linking affected or suspect parts 
to failed parts, help make that decision. While minor differences may 
exist between the OEM tie bolts and the PMA tie bolts, the commenter 
gave no justification as to how those unnamed differences should exempt 
the PMA parts from this AD action. Finally, we did compare design data 
as part of the decision making process.

Request To Withdraw the Proposed AD

    The same commenter requests that we withdraw the proposed AD and 
not re-issue it until we are prepared to fully disclose what design 
features caused the tie bolt failures. The commenter further states 
that since the tie bolt requires a sustained preload for safe 
operation, one would expect that maintenance or assembly practices are 
more likely contributors, as the likelihood of high-cycle-fatigue 
failures increases if the preload is not established or maintained 
correctly.
    We do not agree. While they may have minor differences between 
them, the tie bolts from all four manufacturers are essentially the 
same and share many common features. The commenter provides no data to 
support the assertion that maintenance or assembly practices are more 
likely contributors to the high-cycle-fatigue failures. Analysis of the 
failures did not find any assembly problems. We did not change the AD.

Request To Provide Instructions on How to Make the Engine Airworthy

    The same commenter requests that we provide instructions on how to 
make the engine airworthy. The commenter states that the AD action 
essentially specifies an action of ``remove, and do not reinstall, tie 
bolt part numbers listed in Table 1.'' The commenter assumes there

[[Page 35506]]

will be instructions provided on how to make the engine airworthy.
    We partially agree. While there is no way to make the removed tie 
bolts airworthy, we reworded the AD to include a statement that the 
removed tie bolts be replaced with tie bolts with P/Ns that are not 
listed in Table 1 of the AD.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    About 700 RRC 250-B and 250-C series turboprop and turboshaft 
engines with affected P/Ns of gas producer rotor assembly tie bolts 
manufactured by EXTEX Ltd., Pacific Sky Supply Inc., Rolls-Royce 
Corporation (RRC), and Superior Air Parts Inc., installed on aircraft 
of U.S. registry, will be affected by this AD. We also estimate that it 
will take about 20 workhours per engine to perform the actions, and 
that the average labor rate is $65 per workhour. Required parts will 
cost about $421 per engine. Based on these figures, we estimate the 
total cost of the AD to U.S. operators to be $1,204,700.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
subtitle VII, part A, subpart III, section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under 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.
    We prepared a summary of the costs to comply with this AD 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.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the Federal Aviation Administration amends 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. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

2006-13-06 Rolls-Royce Corporation (formerly Allison Engine Company, 
Allison Gas Turbine Division, and Detroit Diesel Allison): Amendment 
39-14659. Docket No. FAA-2005-22594; Directorate Identifier 2005-NE-
28-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective July 26, 
2006.

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, -B17F, -B17F/1, -B17F/
2, 250-C18, -C20, -C20B, -C20F, -C20J, -C20R, -C20R/1, -C20R/2, -
C20R/4, -C20S, and ``C20W series turboprop and turboshaft engines 
with the gas producer rotor assembly tie bolt part numbers (P/Ns) 
listed in the following Table 1, installed:

                            Table 1.--Affected Gas Producer Rotor Assembly Tie Bolts
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                  Manufacturer                                        Affected part numbers
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EXTEX Ltd. (EXTEX).............................  A23008020 and E23008020
Rolls-Royce Corporation (RRC)..................  23008020, 6843388 and 6876991
Superior Air Parts Inc. (SAP)..................  A23008020
Pacific Sky Supply Inc.........................  23008020P
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    These engines are installed on, but not limited to, aircraft in 
the following Table 2:

                                          Table 2.--Applicable Aircraft
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                Helicopter                                                 Models
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Agusta...................................  A109, A109A, A109A II, A109C.
Arrow Falcon Exporters...................  OH-58A+ and OH-58C.
Bell Textron.............................  206A, 206B, 206L.
Enstrom..................................  TH-28, 480, 480B.
Eurocopter France........................  AS355E, AS355F, AS355F1, AS355F2.
Eurocopter Deutschland...................  BO-105A, BO-105C, BO-105S.

[[Page 35507]]

 
FH-1100 Manufacturing Corp...............  FH-1100.
Garlick..................................  OH-58A + OH-58C.
McDonnell Douglas Company................  369D, 369E, 369F, 369H, 369HM, 369HS, 369HE, 500N.
San Joaquin..............................  OH-58A+ and OH-58C.
Schweizer................................  269D.
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                 Aircraft                                                  Models
----------------------------------------------------------------------------------------------------------------
B-N Group Ltd............................  BN-2T and BN-2T-4R.
SIAI Marchetti s.r.l.....................  SF600, SF600A.
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Unsafe Condition

    (d) This AD results from eleven reports of RRC tie bolt failure 
due to high-cycle-fatigue. We are issuing this AD to prevent tie 
bolt failure that could cause loss of engine power, resulting in a 
first stage turbine wheel overspeed and an uncontained engine 
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.

Remove Gas Producer Rotor Assembly Tie Bolts

    (f) Remove the P/N gas producer rotor assembly tie bolts listed 
in Table 1 of this AD from service the next time they are 
disassembled for any reason, or by October 31, 2011, whichever 
occurs first, and replace with tie bolts with P/Ns that are not 
listed in Table 1 of this AD.
    (g) After the effective date of this AD, do not install any gas 
producer rotor assembly tie bolt P/Ns listed in Table 1 of this AD 
in any RRC 250-B and 250-C Series turboprop and turboshaft engines.

Alternative Methods of Compliance

    (h) The Manager, Los Angeles Aircraft Certification Office, has 
the authority to approve alternative methods of compliance for 
EXTEX, and Pacific Sky Supply Inc. gas producer rotor assembly tie 
bolts 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 gas producer rotor assembly tie bolts addressed in this AD, if 
requested, using the procedures found in 14 CFR 39.19. The Manager, 
Southwest Special Certification Office, has the authority to approve 
alternative methods of compliance for SAP gas producer rotor 
assembly tie bolts addressed in this AD, if requested, using the 
procedures found in 14 CFR 39.19.

Related Information

    (i) RRC Commercial Engine Bulletin (CEB) CEB A-304, CEB A-1371, 
CEB A-72-4076, TP CEB A-176, TP CEB A-1319, TP CEB A-72-2027, 
Revision N/C, dated May 23, 2005, and EXTEX Service Bulletin T-090, 
Revision N/C, dated May 23, 2005, pertain to the subject of this AD.

    Issued in Burlington, Massachusetts, on June 14, 2006.
Francis A. Favara,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 06-5547 Filed 6-20-06; 8:45 am]
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