Airworthiness Directives; CFM International CFM56 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

This amendment revises an existing airworthiness directive (AD) that is applicable to CFM International (CFMI) CFM56-5C series turbofan engines. This action establishes new life limits for certain low pressure turbine rotor (LPTR) stage 3 disks and all high pressure turbine rotor (HPTR) disks listed in the existing AD. This amendment is prompted by the results of an extensive life management program performed by the manufacturer. The actions specified in this AD are intended to prevent low-cycle-fatigue (LCF) failure of certain HPTR front shafts, HPTR front air seals, HPTR disks, booster spools, and LPTR stage 3 disks, which could result in an uncontained engine failure and damage to the airplane.

DATES:

Effective September 24, 2002.

Comments for inclusion in the Rules Docket must be received on or before November 8, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 95-ANE-64-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: “9-ane-adcomment@faa.gov”. Comments sent via the Internet must contain the docket number in the subject line.

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.

SUPPLEMENTARY INFORMATION:

On April 22, 1997, the FAA issued AD 97-09-02, Amendment 39-9998 (62 FR 23642), applicable to CFMI CFM56-5C series turbofan engines, to reduce the LCF retirement lives of certain HPTR front shafts, HPTR front air seals, booster spools, HPTR disks, and LPTR stage 3 disks. That action was prompted by results of a refined life analysis performed by the manufacturer which revealed minimum calculated LCF lives lower than published LCF retirement lives. This condition could result in LCF failure of certain HPTR front shafts, HPTR front air seals, HPTR disks, booster spools, and LPTR stage 3 disks, which could result in an uncontained engine failure and damage to the airplane. Since AD 97-09-02 was issued, the manufacturer conducted an extensive life management program for the LPTR stage 3 disks installed in CFM56-5C2/G and -5C3/G engines and HPTR disks installed in all CFM56-5C series engines. This consisted of a mission cycle based on field data, an updated 2D heat transfer and stress analysis, and a 3D finite element analysis. The results indicated higher LCF retirement lives for certain LPTR stage 3 disks and all HPTR disks than the lives published in AD 97-09-02. Therefore, this revision establishes new life limits for LPTR stage 3 disks part numbers (P/N's) 337-001-602-0 and 337-001-605-0 installed in CFM56-5C2/G and -5C3/G engines and HPTR disk P/N 1498M43P04 installed in all CFM56-5C series engines. Except for CFM56-5C4 engines, the LCF retirement lives for LPTR stage 3 disks part numbers (P/N's) 337-001-602-0 and 337-001-605-0 are now extended to 20,000 cycles-since-new (CSN) in Chapter 05 of the CFM56-5C Engine Shop Manual, CFMI-TP.SM.8. The LCF retirement lives for HPTR disk part number 1498M43P04 are now extended to 7,800 cycles-since-new (CSN) in Chapter 05 of the CFM56-5C Engine Shop Manual, CFMI-TP.SM.8. The cyclic lives of these LPTR stage 3 disks installed in CFM56-5C4 engines, and the cyclic lives of HPTR front shafts P/N's 1498M40P03, 1498M40P05, and 1498M40P06; HPTR front air seals, P/N's 1523M34P02 and 1523M34P03; and booster spools, P/N 337-005-210-0, remain unchanged.

FAA's Determination of an Unsafe Condition and Required Actions

Although these affected engine models are not used on any airplanes that are registered in the United States, the possibility exists these engine models could be used on airplanes that are registered in the United States in the future. This AD establishes new life limits for certain LPTR stage 3 disks and all HPTR disks listed in the existing AD.

Immediate Adoption of This AD

Since there are currently no domestic operators of CFM56-5C series turbofan engines, notice and opportunity for prior public comment are unnecessary. Therefore, a situation exists that allows the immediate adoption of this regulation.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD 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 95-ANE-64-AD.” The postcard will be date stamped and returned to the commenter.

Regulatory Analysis

This final 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 final 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 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. A final evaluation has been prepared for this action and it 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

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.

2. Section 39.13 is amended by removing Amendment 39-9998 ( 62 FR 23642, May 1, 1997), and by adding a new airworthiness directive, Amendment 39-12876, to read as follows:

97-09-02R1 CFM International: Amendment 39-12876. Docket No. 95-ANE-64-AD. Revises AD 97-09-02, Amendment 39-9998.

Applicability

This airworthiness directive (AD) is applicable to CFM International (CFMI) CFM56-5C2/G, -5C3/G, and -5C4 series turbofan engines. These engines are installed on, but not limited to Airbus Industrie A340 series airplanes.

Note 1:

This 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 (i) 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 a low-cycle-fatigue (LCF) failure of the high pressure turbine rotor (HPTR) front shaft, HPTR front air seal, HPTR disk, booster spool, and low pressure turbine rotor (LPTR) stage 3 disk, which could result in an uncontained engine failure and damage to the airplane, do the following:

(a) Remove from service HPTR front shafts, part numbers (P/N's) 1498M40P03, 1498M40P05, and 1498M40P06, before accumulating 8,400 cycles-since-new (CSN), and replace with a serviceable part.

(b) Remove from service HPTR front air seals, P/N's 1523M34P02 and 1523M34P03, before accumulating 4,000 CSN, and replace with a serviceable part.

(c) Remove from service HPTR disks, P/N 1498M43P04, before accumulating 7,800 CSN, and replace with a serviceable part.

(d) Remove from service booster spools, P/N 337-005-210-0, before accumulating 13,000 CSN, and replace with a serviceable part.

(e) For CFM56-5C4 engines only, remove from service LPTR stage 3 disks, P/N's 337-001-602-0 and 337-001-605-0, before accumulating 7,000 CSN, and replace with a serviceable part.

(f) For CFM56-5C2/G and -5C3/G engines only, remove from service LPTR stage 3 disks P/N's 337-001-602-0 and 337-001-605-0, before accumulating 20,000 CSN, and replace with a serviceable part.

(g) This action establishes the new LCF retirement lives stated in paragraphs (a) through (f) of this AD, which are published in Chapter 05 of the CFM56-5C Engine Shop Manual, CFMI-TP.SM.8.

(h) For the purpose of this AD, a serviceable part is one that has not exceeded its respective new life limit as set out in this AD.

Alternative Methods of Compliance

(i) 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 (ECO). The request must be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, 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.

Special Flight Permits

(j) 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.

Effective Date

(k) This amendment becomes effective on September 24, 2002.