AD 97-06-14

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Company CF34 series turbofan engines, that reduces the allowable operating cyclic life limit for affected fan disks. This amendment is prompted by an updated stress and life analysis. The actions specified by this AD are intended to prevent fan disk rupture, engine failure, and damage to the aircraft.

Final rule.

97-06-14 General Electric Company: Amendment 39-9971. Docket 95-ANE-19.

Applicability: General Electric Company (GE) Model CF34-1A, -3A, and -3A2 turbofan engines, with fan disk part numbers (P/N's) 6020T62G04, 6020T62G05, 6078T00G01, or 5921T54G01 installed. These engines are installed on but not limited to Canadair Limited Model CL-600-2A12 and CL-600-2B16 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 (d) 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 rupture, engine failure, and damage to the aircraft, accomplish the following:

(a) Remove from service fan disks, P/N's 6020T62G04, 6020T62G05, 6078T00G01, and 5921T54G01, prior to accumulating 9,000 cycles in service (CIS) since new, and replace with a serviceable part.

(b) For the purpose of this AD, a serviceable part is defined as a fan disk with less than 9,000 CIS.

(c) This AD defines a new life limit of 9,000 CIS for fan disks, P/N's 6020T62G04, 6020T62G05, 6078T00G01, and 5921T54G01.

(d) 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. The request should be forwarded 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.

(e) 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.

(f) This amendment becomes effective on May 27, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to General Electric Company (GE) CF34 series turbofan engines was published in the Federal Register on March 25, 1996 (61 FR 12050). That action proposed to reduce the allowable operating cyclic life limit for affected fan disks.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

There are approximately 440 engines of the affected design in the worldwide fleet. The FAA estimates that 150 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately zero additional work hours per engine to accomplish the required actions. Required parts will cost approximately $106,320 per engine, based on the estimated current part cost, prorated downward by a factor equal to the quotient of the difference between the original cyclic life limit (38,280 cycles) and the revised cyclic life limit (9,000 cycles) divided by the original cyclic life limit. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $15,950,000.

The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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, Incorporation by reference, 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 USC106(g), 40113, 44701. 39.13 - [AMENDED]

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