00-14788. Airworthiness Directives; Airworthiness Directives; CFM International (CFMI) CFM56-2, -2A, -2B, -3, -3B, -3C, -5, -5B, -5C, and -7B Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment supersedes an existing airworthiness directive (AD), applicable to certain CFM International (CFMI) CFM56 series turbofan engines, that requires revisions to the Airworthiness Limitations Section of applicable Engine Shop Manuals (ESMs). These revisions incorporate required enhanced inspection of selected critical life-limited parts at each piece-part exposure. This amendment requires the addition of CFM56 engine models to the applicability section of the AD, and the introduction of additional inspections. This amendment is prompted by additional focused inspection procedures that have been developed by the manufacturer. The actions specified by this AD are intended to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.

DATES:

Effective date December 11, 2000.

ADDRESSES:

The Rules Docket may be examined at the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA 01803-5299.

FOR FURTHER INFORMATION CONTACT:

Robert Ganley, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone [phone], fax [phone].

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 99-08-16, Amendment 39-11122 (64 FR 17962, April 13, 1999), applicable to CFM International (CFMI) CFM56-2, -2A, -2B, -3, -3B, and -3C series turbofan engines, was published in the Federal Register on October 7, 1999 (64 FR 54589). That action proposed to require the addition of CFM56 engine models to the applicability section of the AD and the introduction of additional inspections.

Comments Received

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Effective Date

Several commenters request that the effective date of the AD be set to allow for sufficient time for publication of the procedures, procurement of the equipment, and training.

The FAA agrees. The effective date for the final rule will be set at 180 days after publication in the Federal Register.

Extend Notice of Proposed Rulemaking (NPRM) Comment Period

Two commenters request that the NPRM comment period be extended until after the proposed inspections are published, to allow time for the operators to review the specific inspections that will be required.

The FAA does not agree. The nature and scope of the added inspections are not significantly different from existing inspections. Additionally, the effective date of this AD has been set to 180 days after publication of the AD, to allow time for the specific procedures to be published. Operators may submit comments to the docket file on the specific procedures, once they are published; the FAA will then consider an extension of the effective date or additional rulemaking, as necessary. The FAA does not believe that this final rule should be delayed pending the publication of the inspection procedures.

NPRM Preamble

One commenter notes that the preamble for the NPRM supersedure does not exactly track the preamble for the NPRM for the current AD. Specifically, the commenter notes that the supersedure preamble does not contain the explanation as to when the enhanced disk inspections are required; the commenter is concerned that the inspection program is being changed from the current AD. The commenter requests that the FAA change the preamble for the NPRM supersedure to reflect the content of the NPRM published for the current AD.

The FAA does not agree. The inspection program established by the current AD remains unchanged. This proposal does not change how air carriers must manage the inspection program. As stated in the NPRM for the current AD, future ADs may be issued to introduce additional intervention strategies in order to further reduce uncontained engine failures. This could include ADs that add new parts to the list of parts inspected. The inspection program established by the current AD, however, will remain in place unless specifically altered in a future proposal.

Unsafe Condition

One commenter objects to the language in the preamble of the NPRM supersedure for the second phase of enhanced inspections, which includes a finding of an “unsafe condition.” The commenter requests that the term “unsafe condition” be deleted and replaced with the justification language from the original NPRM.

The FAA does not agree. This commenter does not disagree with the proposed rule itself, but with the term “unsafe condition” contained in the preamble to the NPRM. It is not the intent of the FAA to completely change the enhanced disk inspection program established by the current AD, which evolved as a cooperative effort between the FAA and industry. This intervention strategy was designed to reduce the number of uncontained engine failures by mandating enhanced nondestructive inspections of critical components that could most likely result in a hazard to the airplane in the event of a disk failure. Since the engine maintenance manuals did not mandate these enhanced inspections, the current AD was necessary to establish the inspection program as an airworthiness limitation. Regardless of the fact that it was not stated explicitly in the original NPRM, the FAA determined that an “unsafe condition” existed because the engine maintenance manuals did not contain enhanced inspections as an airworthiness limitation. The intent was not to imply any defect in the actual engine hardware, but simply to state that the maintenance manuals, which form part of the approved engine design, must be revised to mandate the enhanced inspections. The supersedure repeats that finding with respect to the additional parts being added to the enhanced inspection program. Because a finding of an “unsafe condition” is a requirement for the issuance of an AD, future NPRMs to add parts to the program will also include that finding.

Cycles in Service

One commenter requests that the FAA change the cycles in service in paragraph (2)(ii) of the mandatory inspections language contained in paragraph (a) from 100 cycles to 300 cycles. The commenter believes that a 300 cycle interval is more representative of its A-check interval.

The FAA does not agree. The FAA is aware that although cracks can be missed during part inspections, the probability of detecting a crack increases each time a part is processed through an inspection line. Commonly used on-condition maintenance plans make it likely that a given part could be returned to service for thousands of cycles without the need for additional focused inspection. The FAA established the 100 cycle threshold in recognition of the two opposing aspects of part removal and inspection, i.e., a need for a brief exemption period following the performance of mandatory inspections and the benefits of increased frequency of inspection. The time between A-check intervals or crack growth time was not a factor in the determination of the threshold for exempting parts from focused inspection. The threshold is based strictly on keeping the frequency of mandatory inspection as high as practical, to increase the probability of crack detection while providing a brief window of exemption from mandatory inspection if certain conditions are met. The FAA will not revise paragraph (2)(ii) of the mandatory inspections language in paragraph (a) of the final rule.

Estimated Annual Cost

One commenter suggests that the total estimated annual cost of $870 per engine for the proposed inspections is not accurate. The commenter suggests that a total annual cost of $2,271 per engine is more accurate, based on its estimation of piece-part exposure rate.

The FAA does not agree. The total estimated annual cost per engine noted in the economic analysis of the NPRM is representative of the piece-part exposure rate of all affected U.S. operators, not one specific operator. The FAA will not revise the economic analysis of the final rule.

Addition to Applicability Section

One commenter suggests adding the Airbus Industrie A318 and Boeing C-135 (military) series airplanes to the applicability section of the final rule.

The FAA partially agrees. Currently, no A318 aircraft are powered by CFM56 engines; this series will not be added to the final rule. The applicability section of the final rule will be revised to add the Boeing C-135 (military) series airplanes; the Boeing KE-3 (military) and RC-135 (military) series airplanes will also be added, to be complete.

Clarification of Paragraph (e)

One commenter requests that the FAA delete the phrase “of this chapter” from the first sentence of paragraph (e) of the compliance section, to improve the clarity of this paragraph.

The FAA agrees. The words “of this chapter” have been deleted from paragraph (e).

“Time Limits Section”

One commenter recommends replacing references to the “Time Limits Section” with references to the more general “Airworthiness Limitations Section,” since Chapter 5 now contains two subsets, 05-11-00 for life limits and 05-21-00 for mandatory inspections. The commenter also recommends replacing the references to “chapter 05-11-00” with “chapter 05-00-00.”

Another commenter recommends replacing references to the “Time Limits Section” with “Life Limits Section,” to eliminate confusion. The commenter also recommends replacing references to “chapter 05-11-00” with “chapter 05-21-00,” because Chapter 5 now contains a new section, 05-21-00, for the mandatory inspections.

The FAA partially agrees. The references to the “Time Limits Section” have been changed in the final rule to the more general “Airworthiness Limitations Section.” The references to “chapter 05-11-00” have been changed in the final rule to “chapter 05-00-00.”

Revisions to the Table

Three commenters suggest revising the table in paragraph (1) of the mandatory inspections language contained in paragraph (a) of the proposed AD to correct minor typographical errors to eliminate confusion. The suggested revisions are as follows:

• Replace “Bold” with “Bolt” in the Inspection column for the CFM56-2/-2A/-2B/-3/-3B/-3C HPT Disk;
• Replace “Bold” with “Rim Bolt” in the Inspection column for the CFM56-2/-2A/-2B/-3/-3B/-3C HPT Disk; and
• Replace “Disk” with “Seal” in the Inspection column for the HPT Front Rotating Air Seal.

The FAA agrees. The FAA has corrected the typographical errors and has also made the following corrections:

• Replaced “-B” with “-2B” in the Engine models column for the HPT Disk; and
• Capitalized the word “rotating” in the Part name column for the CFM56-5/-5B/-5C/-7B.

Adoption of the Rule as Proposed

Three commenters support the adoption of the rule as proposed.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Economic Analysis

There are approximately 6,953 engines of the affected design in the worldwide fleet. The FAA estimates that 2,453 engines installed on airplanes of U.S. registry will be affected by this AD, that it will take approximately 30 work hours per engine for the fan disk inspection, 13 work hours for the HPT disk inspection, and 13 work hours for the HPT front rotating air seal inspection. The average labor rate is $60 per work hour. Using average shop visitation rates, 554 fan disks, 891 HPT disks, and 563 HPT front rotating air seals are expected to be affected per year. The total estimated annual cost of the AD on U.S. operators is approximately $2,131,320, or $870 per engine.

Regulatory Impact

This rule does not have federalism implications, as defined in Executive Order 13132, because it does 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 rule.

For the reasons discussed above, I certify that this action (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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

Adoption of the Amendment

Accordingly, pursuant to 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. Section 39.13 is amended by removing Amendment 39-11122 ( 64 FR 17962, April 13, 1999) and by adding a new airworthiness directive, Amendment 39-11779, to read as follows:

2000-12-01 CFM International: Amendment 39-11779. Docket No. 98-ANE-38-AD. Supersedes AD 99-08-16, Amendment 39-11122.

Applicability: CFM International (CFMI) CFM56-2, -2A, -2B, -3, -3B, -3C, -5, -5B, -5C, and -7B series turbofan engines, installed on but not limited to McDonnell Douglas DC-8 series, Boeing 737 series, Airbus Industrie A319, A320, A321, and A340 series, as well as Boeing C-135, E-3, E-6, KC-135, KE-3, and RC-135 (military) series airplanes.

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 (c) 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 critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:

Inspections

(a) Within the next 30 days after the effective date of this AD, revise the Airworthiness Limitations Section (chapter 05-00-00) of Engine Shop Manual (ESM) CFMI-TP.SM.4 for CFM56-2 series engines, ESM CFMI-TP.SM.6 for CFM56-2A/-2B series engines, ESM CFMI-TP.SM.5 for CFM56-3/-3B/-3C series engines, ESM CFMI-TP.SM.7 for CFM56-5 series engines, ESM CFMI-TP.SM.9 for CFM56-5B series engines, ESM CFMI-TP.SM.8 for CFM56-5C series engines, and ESM CFMI-TP.SM.10 for CFM56-7B series engines, and for air carrier operations, revise the approved continuous airworthiness maintenance program, by adding the following:

“MANDATORY INSPECTIONS

(1) Perform inspections of the following parts at each piece-part opportunity in accordance with the Inspection/Check section instructions provided in the applicable manual sections listed below:

Engine models	Part name	Engine manual section	Inspection
All	Fan Disk (All Part Number (P/N))	72-21-03	Disk Fluorescent Penetrant Inspection (FPI) and Disk Bore and Dovetail Eddy Current Inspection (ECI).
CFM56-2/-2A/-2B/-3/-3B/-3C	High Pressure Turbine (HPT) Disk (All P/N)	72-52-02	Disk FPI and Disk Bore and Rim Bolt Hole(s) ECI.
CFM56-5/-5B/-5C/-7B	HPT Disk (All P/N)	72-52-02	Disk FPI and Disk Bore ECI.
CFM56-2A/-2B/-3/-3B/-3C	HPT Front Rotating Air Seal (All P/N)	72-52-03	Seal FPI and Seal Bore and Bolt Hole(s) ECI.
CFM56-5/-5B/-5C/-7B	HPT Front Rotating Air Seal (All P/N)	72-52-03	Seal FPI and Seal Bore ECI and Seal Bolt Hole(s) Focused FPI.
CFM56-2	HPT Front Rotating Air Seal (All P/N)	72-52-03	Seal FPI and Seal Bore ECI and Seal Bolt Hole(s) ECI or focused FPI as applicable.

(2) For the purposes of these mandatory inspections, piece-part opportunity means:

(i) The part is considered completely disassembled when accomplished in accordance with the disassembly instructions in the manufacturer's engine manual; and

(ii) The part has accumulated more than 100 cycles in service since the last piece-part opportunity inspection, provided that the part was not damaged or related to the cause for its removal from the engine.”

(b) Except as provided in paragraph (c) of this AD, and notwithstanding contrary provisions in § 43.16 of the Federal Aviation Regulations (14 CFR 43.16), these mandatory inspections shall be performed only in accordance with the Airworthiness Limitations Section of the manufacturer's ESM.

Alternative Methods of Compliance

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

Note 2:

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

Ferry Flights

(d) 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 accomplished.

Continuous Airworthiness Maintenance Program

(e) FAA-certificated air carriers that have an approved continuous airworthiness maintenance program in accordance with the record keeping requirement of § 121.369(c) of the Federal Aviation Regulations (14 CFR 121.369(c)) must maintain records of the mandatory inspections that result from revising the Airworthiness Limitations Section of the applicable ESM and the air carrier's continuous airworthiness program. Alternately, certificated air carriers may establish an approved system of record retention that provides a method for preservation and retrieval of the maintenance records that include the inspections resulting from this AD, and include the policy and procedures for implementing this alternate method in the air carrier's maintenance manual required by § 121.369(c) of the Federal Aviation Regulations (14 CFR 121.369(c)); however, the alternate system must be accepted by the appropriate PMI and require the maintenance records be maintained either indefinitely or until the work is repeated. Records of the piece-part inspections are not required under § 121.380(a)(2)(vi) of the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)). All other operators must maintain the records of mandatory inspections required by the applicable regulations governing their operations.

Note 3:

The requirements of this AD have been met when the ESM changes are made and air carriers have modified their continuous airworthiness maintenance plans to reflect the requirements in the applicable ESM.

Effective Date

(f) This amendment becomes effective on December 11, 2000.

Issued in Burlington, Massachusetts, on June 5, 2000.

Diane S. Romanosky,

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