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Proposed Rule

Airworthiness Directives; CFM International, S.A. CFM56-3, -3B, and -3C Series Turbofan Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to CFM International, S.A. CFM56-3, -3B, and -3C series turbofan engines. This proposal would discontinue use of certain lubricants no longer on the manufacturer's approved list. In addition, this proposal would require a one-time fan disk dovetail wear measurement, and if wear exceeds certain limits, require an ultrasonic inspection for cracks in the fan disk, and, if necessary, require removal from service of fan disks and replacement with serviceable parts. This proposal is prompted by reports of fan disk heavy wear and cracks. The actions specified by the proposed AD are intended to prevent fan disk failure, which could result in an uncontained engine failure and damage to the aircraft.

DATES:

Comments must be received by April 3, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-57-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be submitted to the Rules Docket by using the following Internet address: “9-ane-adcomment@faa.gov”. Comments may be inspected at this location between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from CFM International, S.A., Technical Publications Department, 1 Neumann Way, Cincinnati, OH 45215; telephone 513-552-2981, fax 513-552-2816. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

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FOR FURTHER INFORMATION CONTACT:

Glorianne Niebuhr, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone 781-238-7132, fax 781-238-7199.

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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 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 notice 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 98-ANE-57-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

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. 98-ANE-57-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

The Federal Aviation Administration (FAA) has received reports of fan disk heavy wear and cracks on CFM International, S.A. CFM56-3, -3B, and -3C series turbofan engines. In one case, an inflight engine shutdown resulted from fan blade failure at the root area just above the pressure face. In addition, one fan disk was found cracked during a routine fluorescent penetrant inspection (FPI) and exhibited heavy wear on the pressure face. Investigation revealed high stress around the dovetail pressure face resulting from the use of certain fan disk dovetail lubricants coupled with the presence of certain fan blade/damper configurations. This condition, if not corrected, could result in fan disk failure, which could result in an uncontained engine failure and damage to the aircraft.

Service Information

The FAA has reviewed and approved the technical contents of CFM International, S.A. CFM56-3/-3B/-3C Service Bulletin (SB) No. 72-854, Revision 2, dated November 29, 1999, that describes procedures for the one-time on-wing fan disk dovetail wear measurement and fan disk ultrasonic inspection. This AD allows the ultrasonic inspection to be done on-wing or in the shop.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would discontinue use of certain lubricants no longer on the manufacturer's approved list. In addition, this proposal would require a one-time fan disk dovetail wear measurement, and if wear exceeds certain limits, require an ultrasonic inspection for cracks in the fan disk, and, if necessary, require removal from service of fan disks and replacement with serviceable parts. The compliance times are based upon the fan blade/damper configuration and engine thrust rating. The actions would be required to be accomplished in accordance with the SB described previously.

Economic Analysis

There are approximately 600 engines of the affected design in the worldwide fleet. The FAA estimates that 510 engines installed on aircraft of US registry would be affected by this proposed AD, that it would take approximately 9 work hours per engine to accomplish the inspections and replacement of blades and dampers, and that the average labor rate is $60 per work hour. Required parts would cost approximately $10,700 per engine for the required fan blade/damper configuration. The manufacturer has informed the FAA that an estimated 140 engines may need fan disk replacement, at $56,799 per engine. In addition, the FAA estimates that 159 work hours would be required to remove the engine from the aircraft, replace the fan disk, and return the engine to service. Based on these figures, the total cost impact of the proposed AD on US operators is estimated to be $15,019,860. Start Printed Page 11506

Regulatory Impact

This proposal does not have federalism implications, as defined in Executive Order No. 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 proposal.

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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

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

CFM International, S.A.: Docket No. 98-ANE-57-AD.

Applicability: CFM International, S.A (CFMI) CFM56-3, -3B, and -3C series turbofan engines, installed on but not limited to Boeing 737 series aircraft.

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 (h) 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: Required as indicated, unless accomplished previously.

To prevent fan disk failure, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

Wear Measurement (Thrust Rating Category A Only)

(a) For CFM56-3, -3B, and -3C series engines operating at the category A thrust rating on the effective date of this AD, that have never previously operated at the category B or C thrust ratings, perform a one time fan disk dovetail wear measurement in accordance with section 2.B.(1) of CFMI CFM56-3/-3B/-3C Service Bulletin (SB) No. 72-854, Revision 2, dated November 29, 1999, using the intervals defined in section 1.D.(1)(a) of the SB, and the current fan disk time and cycles on the effective date of the AD.

Inspection

(1) Perform a local ultrasonic inspection for cracks in the fan disk in accordance with section 2.B.(2) of the SB, if required by the wear criteria described in section 1.D.(1)(b) 1 of the SB.

Removal

(i) Remove from service prior to further flight fan disks that do not meet the ultrasonic inspection criteria defined in paragraph 2.B.(2) (d) 8 b of the SB, and replace with a serviceable part.

(ii) Remove from service within 50 cycles in service (CIS), fan disks that meet the ultrasonic inspection criteria defined in paragraph 2.B.(2) (d)8 b of the SB, if the wear measurement is greater than or equal to 9 mils.

(2) Install dampers, as required, in accordance with the compliance times and criteria described in section 1.D.(1)(b) 1 of the SB.

Wear Measurement (Thrust Rating Category A, if the Engine Was Previously Operated at Thrust Rating Categories B or C)

(b) For CFM56-3, -3B, and -3C series engines operating at the category A thrust rating on the effective date of this AD, that have previously operated at the category B or category C thrust ratings, perform a one-time fan disk dovetail wear measurement in accordance with section 2.B.(1) of CFMI CFM56-3/-3B/-3C SB No. 72-854, Revision 2, dated November 29, 1999, using the intervals defined in section 1.D.(1)(a) of the SB, and the current fan disk time and cycles on the effective date of the AD.

Inspection

(1) Perform a local ultrasonic inspection for cracks in the fan disk in accordance with section 2.B.(2) of the SB, if required by the wear criteria described in section 1.D.(1)(b) 2 of the SB.

Removal

(i) Remove from service prior to further flight fan disks that do not meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, and replace with a serviceable part.

(ii) Remove from service within 50 CIS, fan disks that meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, if the wear measurement is greater than or equal to 9 mils.

(2) Install dampers, as required, in accordance with the compliance times and criteria described in section 1.D.(1)(b) 2 of the SB.

Wear Measurement (Thrust Rating Category B, Regardless of Whether the Engine Was Previously Operated at Thrust Rating Categories A or C)

(c) For CFM56-3B and -3C series engines operating at the category B thrust rating on the effective date of this AD, regardless of whether the engine was previously operated at thrust rating categories A or C, perform a one-time fan disk dovetail wear measurement in accordance with section 2.B.(1) of CFMI CFM56-3/-3B/-3C SB No. 72-854, Revision 2, dated November 29, 1999, using the intervals defined in section 1.D.(1)(a) of the SB, and the current fan disk time and cycles on the effective date of the AD.

Inspection

(1) Perform a local ultrasonic inspection for cracks in the fan disk in accordance with section 2.B.(2) of the SB, if required by the wear criteria described in section 1.D.(1)(c) of the SB.

Removal

(i) Remove from service prior to further flight fan disks that do not meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, and replace with a serviceable part.

(ii) Remove from service within 50 CIS, fan disks that meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, if the wear measurement is greater than or equal to 9 mils.

(2) Remove and replace fan blades and install dampers, as required, in accordance with the compliance times and criteria described in section 1.D.(1)(c) of the SB.

Wear Measurement (Thrust Rating Category C, Regardless of Whether the Engine Was Previously Operated at Thrust Rating Categories A or B)

(d) For CFM56-3C series engines operating at the category C thrust rating on the effective date of this AD, regardless of whether the engine was previously operated at category A or B thrust ratings, perform a one-time fan disk dovetail wear measurement in accordance with section 2.B.(1) of CFMI CFM56-3/-3B/-3C SB No. 72-854, Revision 2, dated November 29, 1999, using the intervals defined in section 1.D.(1)(a) of the SB, and the current fan disk time and cycles on the effective date of the AD. Start Printed Page 11507

Inspection

(1) Perform a local ultrasonic inspection for cracks in the fan disk in accordance with section 2.B.(2) of the SB, if required by the wear criteria described in section 1.D.(1)(d) of the SB.

Removal

(i) Remove from service prior to further flight fan disks that do not meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, and replace with a serviceable part.

(ii) Remove from service within 50 CIS, fan disks that meet the ultrasonic inspection criteria defined in paragraph 2.B.(2)(d)8 b of the SB, if the wear measurement is greater than or equal to 5 mils.

(2) [Reserved]

(e) If the fan disk is determined to be serviceable, clean and lubricate the fan disk and fan blade using the instructions in paragraph 2.B.(2)(d)8 d of the SB.

Definitions

(f) The category A, B, and C thrust ratings listed in paragraphs (a) through (d) of this AD are defined in chapter 05 of the CFM56-3 model series Engine Shop Manual, CFMI-TP.SM.5.

Lubricants

(g) After the effective date of this AD, the following lubricants are no longer approved for use on the CFMI CFM56-3, -3B, and -3C series engines: Sandstrom 27A, ZIP D5460, Surf-kote A 1625, Tiolube 70 and Tiolube 75/75.

Alternative Methods of Compliance

(h) 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, Engine Certification Office. Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Engine Certification Office.

Note 2:

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

Ferry Flights

(i) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

Start Signature

Issued in Burlington, Massachusetts, on February 24, 2000.

David A. Downey,

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

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[FR Doc. 00-5012 Filed 3-2-00; 8:45 am]

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