05-6108. Airworthiness Directives; Rolls-Royce Corporation (Formerly Allison Engine Company) 501-D22A, 501-D22C, and 501-D22G Turboprop Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for Rolls-Royce Corporation (RRC) (formerly Allison Engine Company) 501-D22A, 501-D22C, and 501-D22G turboprop engines. This proposed AD would require a onetime inspection for proper metal hardness of certain 1st stage, 2nd stage, 3rd stage, and 4th stage turbine wheels. This proposed AD results from a report of a turbine wheel found to be over dimensional limits, caused by improper metal hardness. We are proposing this AD to prevent uncontained turbine wheel failure, leading to damage of the airplane and total loss of engine power.

DATES:

We must receive any comments on this proposed AD by May 31, 2005.

ADDRESSES:

Use one of the following addresses to comment 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 20590-0001.
• 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 can get the service information identified in this proposed AD from Rolls-Royce Corporation, P.O. Box 420, 2001 South Tibbs Avenue, Indianapolis, IN 46206-0420; telephone [phone]; fax [phone].

You may examine the comments on this proposed AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Michael Downs, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, 2300 East Devon Avenue, Des Plaines, IL 60018; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-20742; Directorate Identifier 2005-NE-03-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.

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 [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.

Discussion

During the rebuild of an RRC 501 industrial engine's 1st stage turbine wheel that had accumulated 31,000 hours time-in-service, the assembled turbine blade lengths were found to be varying up to 0.012-inch beyond the blade tip run-out limit. The shop inspector considered the turbine wheel suspect and returned it to RRC for metallurgical evaluation. That evaluation revealed that a portion of the turbine wheel had an increased radius, over the maximum radius limit, and a metal hardness below design requirements. RRC reviewed the forging furnace records at the forging plant that heat-treated the turbine wheel. The records showed that the temperature of the heat-treatment solution was about 100 degrees Fahrenheit below the minimum required temperature, for about two hours during the heat-treatment process. RRC reports that the effects of the improper heat treatment are a reduction in metal strength, lower tensile yield, and probability of metal creep, stress rupture, and metal fatigue. The same forging plant heat-treated RRC 501-D22A, 501-D22C, and 501-D22G turboprop engine 1st stage, 2nd stage, 3rd stage, and 4th stage turbine wheels. Those turbine wheels are suspect for improper metal hardness. This condition, if not corrected, could result in uncontained turbine wheel failure, leading to airplane damage and total loss of engine power.

Relevant Service Information

We have reviewed and approved the technical contents of Rolls-Royce Commercial Engine Bulletins (CEBs) No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004. These bulletins describe procedures for performing a onetime inspection for proper metal hardness of certain 1st stage, 2nd stage, 3rd stage, and 4th stage turbine wheels.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which would require a onetime inspection for proper metal hardness of certain 1st stage, 2nd stage, 3rd stage, and 4th stage turbine wheels. These inspections would be done at the next shop visit of the engine or turbine module, but not to exceed 7,400 cycles-since-new of any 1st stage, 2nd stage, 3rd stage, or 4th stage turbine wheel. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

There are about 150 RRC 501-D22A, 501-D22C, and 501-D22G turboprop engines of the affected design in the worldwide fleet. We estimate that 150 engines installed on airplanes of U.S. registry would be affected by this proposed AD. We also estimate that it would take about 0.5 work hour per engine to perform the proposed actions, and that the average labor rate is $65 per work hour. Required parts would cost about $1,495 per turbine wheel. The manufacturer has stated that it may provide replacement parts for turbine wheels that do not meet inspection criteria, at no cost to operators. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $229,125.

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 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.

§ 39.13

[Amended]

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

Rolls-Royce Corporation (formerly Allison Engine Company): Docket No. FAA-2005-20742; Directorate Identifier 2005-NE-03-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by May 31, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Rolls-Royce Corporation (RRC) (formerly Allison Engine Company) 501-D22A, 501-D22C, and 501-D22G turboprop engines with the turbine wheels listed in the following Table 1, installed.

Table 1.—Affected Turbine Wheels

Turbine wheel part No.	Turbine wheel	Serial Nos.
6875431	1st Stage	KK50152 through KK50199.
6845592	2nd Stage	KK40998 through KK41057.
6845593	3rd Stage	KK36452 through KK36461, and KK36492 through KK36532.
6870434	4th Stage	KK40320 through KK40393, and KK40485 through KK40535.

These engines are installed on, but not limited to, Commercial Hercules L-100-20, L-100-30, L-382B, L-382E, and L-382G, Airbus Super Guppy-201, and Super Convair CV-580A, and CV5800 airplanes.

Unsafe Condition

(d) This AD results from a report of a turbine wheel found to be over dimensional limits, caused by improper metal hardness. We are issuing this AD to prevent uncontained turbine wheel failure, leading to damage of the airplane and total loss of engine power.

Compliance

(e) You are responsible for having the actions required by this AD performed at the next shop visit of the engine or turbine module, but not to exceed 7,400 cycles-since-new of any 1st stage, 2nd stage, 3rd stage, or 4th stage turbine wheel, unless the actions have already been done.

Onetime Inspection for Proper Metal Hardness

(f) Perform a onetime inspection for proper metal hardness of 1st stage, 2nd stage, 3rd stage, and 4th stage turbine wheels. Use paragraphs 2.B. and 2.F. of RRC Commercial Engine Bulletins (CEBs) No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004.

(g) Remove from service any turbine wheel that does not pass inspection, using paragraph 2.C. of RRC CEBs No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004.

(h) Mark the letters, HC, after the serial number on any turbine wheel that passes inspection, using the method described in paragraph 2.D. of RRC CEBs No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004.

Reporting Requirements

(i) Report findings of inspections using the procedures specified in paragraph 2.E. of RRC CEBs No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004. The Office of Management and Budget (OMB) has approved the reporting requirements specified in paragraph 2.E. of RRC CEBs No. CEB-72-1138, No. CEB-72-4051, and No. CEB-72-1584, (combined in one document) dated January 23, 2004, and assigned OMB control number 2120-0056.

Definition

(j) For the purpose of this AD, a serviceable turbine wheel is:

(1) A turbine wheel that has a serial number not listed in this AD; and

(2) A turbine wheel that has a serial number listed in this AD that passed the inspection specified in paragraph (f) of this AD.

Alternative Methods of Compliance

(k) 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.

Related Information

(1) None.

Issued in Burlington, Massachusetts, on March 22, 2005.

Peter A. White,

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