02-26587. Airworthiness Directives; Rolls-Royce Corporation (formerly Allison Engine Company) 501-D Series Turboprop Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to adopt a new airworthiness directive (AD) that is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 501-D series turboprop engines. This proposal would require removal from service of certain turbine rotor components at reduced life limits. This proposal is prompted by the result of recalculated material properties by the manufacturer. The actions specified by the proposed AD are intended to prevent uncontained turbine rotor failure resulting in in-flight engine shutdown and possible damage to the airplane.

DATES:

Comments must be received by December 17, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2001-NE-01-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via the Internet must contain the docket number in the subject line.

The service information referenced in the proposed rule may be obtained from Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206-0420; telephone [phone]; fax [phone]. This information may be examined, by appointment, at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

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

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 in triplicate 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 2001-NE-01-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. 2001-NE-01-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

Before the merger of Allison Engine Company and Rolls-Royce Corporation, Allison Engine Company obtained additional material properties data to enhance their materials database. The additional data showed much higher material property scatter compared to the data originally used to calculate the turbine rotor component life limits. Comparison of the data with other similar alloys showed the manufacturer that the new data, with increased scatter, was indeed representative. As a result, the manufacturer has reduced the life limits of certain second-stage, third-stage, and fourth-stage turbine wheel assemblies, and certain 1st-2nd stage, 2nd-3rd stage, and 3rd-4th stage turbine spacer assemblies.

FAA's Determination of an Unsafe Condition and Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other Rolls-Royce Corporation (formerly Allison Engine Company) 501-D series turboprop engines of the same type design, the proposed AD would require removal from service, and replacement with a serviceable part for:

• Second-stage turbine wheel assemblies part numbers (P/N's) 6847142 and 6876892, before or upon accumulating 12,000 cycles-in-service (CIS), or 16,000 CIS if Allison Engine Company Commercial Overhaul Information Letter (COIL) 401, dated May 1978 has been complied with.
• Third-stage turbine wheel assemblies P/N's 6845883 and 6849743, before or upon accumulating 10,000 CIS, or 13,000 CIS if COIL 401, dated May 1978 has been complied with.
• Third-stage turbine wheel assembly P/N 6855083, before or upon accumulating 10,000 CIS.
• Fourth-stage turbine wheel assembly P/N 6876468, before or upon accumulating 18,000, or 24,000 CIS if COIL 401, dated May 1978 has been complied with.
• 1st-2nd stage spacer assemblies P/N's 6844632 and 23033463, before or upon accumulating 4,700 CIS.
• 1st-2nd stage spacer assembly P/N 23056966, before or upon accumulating 8,000 CIS.
• 2nd-3rd stage spacer assembly P/N 23033456, before or upon accumulating 4,000 CIS.
• 3rd-4th stage spacer assembly P/N 6844794 with serial number (SN) less than and including KK22951, except KK21556, KK21910, KK22814, KK22820, KK22868, and all SN's with an MM prefix, before or upon accumulating 5,100 CIS.

Economic Analysis

There are approximately 930 Rolls-Royce 501-D series turboprop engines of the affected design in the worldwide fleet. The FAA estimates that 684 engines installed on aircraft of U.S. registry would be affected by this proposed AD. The proposed action does not impose any additional labor costs if performed at the time of scheduled engine overhaul. Required parts would cost approximately $45,000 per engine. Based on these figures, the total cost of the proposed AD to U.S. operators is estimated to be $30,780,000.

Regulatory Analysis

This proposed rule 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 proposed rule.

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 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. Section 39.13 is amended by adding the following new airworthiness directive:

Rolls-Royce Corporation: Docket No. 2001-NE-01-AD.

Applicability: This airworthiness directive (AD) is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 501-D series turboprop engines. These engines are installed on, but not limited to Lockheed 188 series and 382 series turboprop airplanes, and Convair Models 340 and 440 airplanes which have had Rolls-Royce Corporation 501-D series turboprop engines installed under a Supplemental Type Certificate. These models are commonly referred to as Convair 580/580A or 5800 models.

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 (e) 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 this AD is required as indicated, unless already done.

To prevent uncontained turbine rotor failure, resulting in in-flight engine shutdown and possible damage to the airplane, do the following:

501-D13 Series Engines

(a) For 501-D13 series engines, remove turbine wheels and spacers from service as specified in the following Table 1:

Table 1.—501-D13 Series Life Limits

Part name	Part number	Life limit for wheels that have complied with commercial overhaul information letter (COIL) 401, dated May 1978	Life limit for wheels that have not complied with COIL 401, dated May 1978
(1) Second-stage turbine wheel assembly	6847142 and 6876892	Remove from service before or upon accumulating 16,000 cycles-in-service (CIS)	Remove from service before or upon accumulating 12,000 CIS.
(2) Third-stage turbine wheel assembly	6845883 and 6849743	Remove from service before or upon accumulating 13,000 CIS	Remove from service before or upon accumulating 10,000 CIS.
(3) Fourth-stage turbine wheel assembly	6876468	Remove from service before or upon accumulating 24,000 CIS	Remove from service before or upon accumulating 18,000 CIS.

(b) Information on 501-D13 series engine turbine life limits can be found in Rolls-Royce Commercial Service Letter (CSL) No. CSL-120, Revision No. 52, dated July 22, 2002.

501-D22 Series Engines

(c) For 501-D22 series engines, remove turbine wheels and spacers from service as specified in the following Table 2:

Table 2.—501-D22 Series Life Limits

Part name	Part number	Remove from service
(1) Third-stage turbine wheel assembly	6855083	Before or upon accumulating 10,000 cycles-in-service (CIS).
(2) 1st-2nd-stage spacer assembly	6844632 and 23033463	Before or upon accumulating 4,700 CIS.
(3) 1st-2nd-stage spacer assembly	23056966	Before or upon accumulating 8,000 CIS.
(4) 2nd-3rd-stage spacer assembly	23033456	Before or upon accumulating 4,000 CIS.
(5) 3rd-4th-stage spacer assembly	6844794	Before or upon accumulating 5,100 CIS, with SN less than and including KK22951, except KK21556, KK21910, KK22814, KK22820 and KK22868, and all SN's with an MM prefix.

(d) Information on 501-D22 series engine turbine life limits can be found in Rolls-Royce Commercial Service Letter (CSL) No. CSL-1001, Revision No. 19, dated July 22, 2002.

Alternative Methods of Compliance

(e) 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 (ACO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ACO.

Special Flight Permits

(f) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be done.

Issued in Burlington, Massachusetts, on October 11, 2002.

Mark C. Fulmer,

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