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Airworthiness Directives; General Electric CF34-8C1 Turbofan Engines

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Information about this document as published in the Federal Register.

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Federal Aviation Administration, DOT.


Final rule.


This amendment adopts a new airworthiness directive (AD), that is applicable to General Electric (GE) CF34-8C1 turbofan engines. This amendment requires replacing combustion chamber assemblies, part number (P/N) 4126T87G04, before accumulating a new reduced cyclic life limit. This amendment is prompted by stress and life analysis conducted by GE. The actions specified by this AD are intended to prevent rupture of the combustion chamber assembly and possible engine fire.


Effective June 12, 2003.


Information regarding this action may be examined, by appointment, at the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

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Eugene Triozzi, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7148; fax (781) 238-7199.

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A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that is applicable to GE CF34-8C1 turbofan engines was published in the Federal Register on February 7, 2003, (68 FR 6379). That action proposed to require replacing combustion chamber assemblies, P/N 4126T87G04, before accumulating a new reduced cyclic life limit.


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

One commenter requests that the combustion chamber assembly life be reduced to 25,800 cycles-since-new (CSN) from the proposed 28,000 CSN. The commenter states that this limit is specified in the GE CF34-8C1 Engine Maintenance Manual life limits section.

The FAA does not agree. The 28,000 life limit is the correct life limit approved by the FAA for combustion chamber assembly, P/N 4126T87G04. The GE manual incorrectly lists the lower life limit. That limit was submitted by GE for FAA approval in December, 2001. Subsequently, GE submitted a request to amend the cycle life limit to 28,000 CSN and the FAA approved it in March, 2002.

After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed. 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 115 GE CF34-8C1 turbofan engines of the affected design in the worldwide fleet. The FAA estimates that 75 engines are installed on airplanes of U.S. registry. The FAA also estimates that it would take approximately 24 work hours per engine to perform the actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $75,000 per engine. Based on these figures and the cost of lost life of 9,800 cycles-since-new per engine, the total cost of the AD to U.S. operators is estimated to be $1,600,000.

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.

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List of Subjects in 14 CFR Part 39

  • Air transportation
  • Aircraft
  • Aviation safety
  • Safety
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Adoption of the Amendment

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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:

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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.

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2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

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2003-09-14 General Electric: Amendment 39-13143. Docket No. 2002-NE-23-AD.

Applicability: This airworthiness directive (AD) is applicable to General Electric (GE) CF34-8C1 turbofan engines with combustion chamber assembly, part number (P/N) 4126T87G04, installed. These engines are installed on, but not limited to Bombardier Inc. Model CL-600-2C10 (CRJ-700 & 701) 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 (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: Compliance with this AD is required as indicated, unless already done.

To prevent rupture of the combustion chamber assembly and possible engine fire, do the following:

(a) Replace combustion chamber assembly, P/N 4126T87G04, at or before the combustion chamber assembly accumulates 28,000 cycles-since-new (CSN).

(b) After the effective date of this AD, do not install any combustion chamber assembly, P/N 4126T87G04, that exceeds 28,000 CSN.

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 Manager, Engine Certification Office (ECO). Operators must submit their request through an appropriate Start Printed Page 24615FAA 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.

Effective Date

(d) This amendment becomes effective on June 12, 2003.

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Issued in Burlington, Massachusetts, on May 1, 2003.

Francis A. Favara,

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

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[FR Doc. 03-11266 Filed 5-7-03; 8:45 am]