04-15508. Airworthiness Directives; Rolls-Royce Corporation (Formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) Models 250-C28, -C28B, and -C28C Turboshaft Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) (RRC) models 250-C28, -C28B, and -C28C turboshaft engines with certain serial number (SN) third-stage turbine wheels, part number (P/N) 6899383. This AD requires replacing certain SN third-stage turbine wheels, P/N 6899383, before reaching new reduced life limits. This AD results from three reports of third-stage turbine blade and shroud failures. We are issuing this AD to prevent loss of power and uncommanded engine shutdown due to failure of third-stage turbine blades and shrouds.

DATES:

This AD becomes effective July 26, 2004.

We must receive any comments on this AD by September 7, 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: [phone].
• 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 AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

John Tallarovic, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, 2300 East Devon Avenue, Des Plaines, IL 60018-4696; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

On May 4, 2004, we became aware of three reports of third-stage turbine wheel blade and shroud failures on RRC model 250-C28 series turboshaft engines. Investigation by RRC revealed that high cycle fatigue caused the third-stage turbine blade and shroud failures. Investigation has also revealed that this high cycle fatigue condition is limited to a population of 73 third-stage turbine wheels that were manufactured and accepted with a blueprint variance. The turbine wheel original life limits were 4,550 operating hours and 6,000 cycles-in-service. This condition, if not corrected, could result in loss of power and uncommanded engine shutdown due to failure of third-stage turbine blades and shrouds.

FAA's Determination and Requirements of This AD

The unsafe condition described previously is likely to exist or develop on other RRC 250-C28 series engines of the same type design. We are issuing this AD to prevent loss of power and uncommanded engine shutdown due to failure of third-stage turbine blades and shrouds. This AD requires replacing the third-stage turbine wheels, P/N 6899383, with SNs listed in the compliance section of this proposed AD at the following:

• For any turbine wheel with fewer than 250 operating hours time since new (TSN) on the effective date of the proposed AD, before accumulating 300 operating hours TSN; and
• For any turbine wheel with 250 or more operating hours TSN on the effective date of the proposed AD, before accumulating an additional 50 operating hours.

FAA's Determination of the Effective Date

Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

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-2004-18538.” Each DMS docket also lists the Directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. FAA-2004-18538; Directorate Identifier 2004-NE-29-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it.

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 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 with 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 AD, 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 [phone]) 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.

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 the 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. 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

Under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

2004-14-02 Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison): Amendment 39-13711. Docket No. FAA-2004-18538; Directorate Identifier 2004-NE-29-AD.

Effective Date

(a) This airworthiness directive (AD) becomes effective July 26, 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) (RRC) models 250-C28, -C28B, and -C28C turboshaft engines with third-stage turbine wheels, part number (P/N) 6899383, listed by serial number (SN) in the following Table 1:

Table 1.—SNs of Affected Third Stage Turbine Wheels

HX91922	X523242	X523281
HX91923	X523243	X523283
HX91925	X523244	X523284
HX91926	X523246	X523287
HX91928	X523249	X523288
HX91929	X523250	X523289
HX91930	X523251	X523290
HX91932	X523253	X523291
HX91934	X523255	X523292
HX91936	X523257	X523293
HX91937	X523260	X523294
HX91939	X523261	X523295
HX91940	X523262	X523296
HX91960	X523263	X523297
HX91962	X523264	X523298
HX91966	X523265	X523300
HX91976	X523266	X523305
HX91977	X523268	X523309
HX91979	X523269	X523313
HX91980	X523270	X523315
X523236	X523271	X523317
X523237	X523273	X523319
X523238	X523276	X523320
X523239	X523277	N/A
X523241	X523278	N/A

These engines are installed on, but not limited to, Bell Helicopter Textron 206L-1; Eurocopter Deutschland BO 105 LS A-1; and Eurocopter Canada BO 105 LS A-3 helicopters.

Unsafe Condition

(d) This AD results from three reports of third-stage turbine wheel blade and shroud failures. We are issuing this AD to prevent loss of power and uncommanded engine shutdown due to failure of the third-stage turbine wheel blade and shroud.

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.

(f) For any third-stage turbine wheel with fewer than 250 operating hours time since new (TSN) on the effective date of this AD, replace turbine wheel before accumulating 300 operating hours TSN.

(g) For any third-stage turbine wheel with 250 or more operating hours TSN on the effective date of this AD, replace turbine wheel before accumulating an additional 50 operating hours.

Definition

(h) For the purposes of this AD, a replacement third-stage turbine wheel is a turbine wheel that does not have a SN listed in this AD.

(i) After the effective date of this AD, do not install third-stage turbine wheels that are listed in Table 1 of this AD, into any engine.

Alternative Methods of Compliance

(j) The Manager, Chicago Aircraft Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.

Special Flight Permits

(k) Under 14 CFR 39.23, we are prohibiting special flight permits for this AD.

Material Incorporated by Reference

(l) None.

Related Information

(m) Rolls-Royce Corporation Alert Commercial Engine Bulletin No. CEB-A-72-2202, dated May 6, 2004, pertains to the subject of this AD.

Issued in Burlington, Massachusetts, on July 1, 2004.

Francis A Favara,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.