00-21054. Airworthiness Directives; General Electric Company CF34 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of Proposed Rule Making; Revision.

SUMMARY:

This document proposes to revise an existing airworthiness directive (AD), applicable to General Electric Company CF34 series turbofan engines. That AD currently requires revisions to the Engine Maintenance Program specified in the manufacturer's Instructions for Continued Airworthiness (ICA) for General Electric Company (GE) CF34 series turbofan engines. Those revisions require enhanced inspection of selected critical life-limited parts at each piece-part exposure. That AD also requires that an air carrier's approved continuous airworthiness maintenance program incorporate these inspection procedures. This action would require the removal of certain inspection requirements for parts removed from engines mounted on-wing. This proposal is prompted by the high removal rate and subsequent piece-part exposure of fan disks due to certain mandatory maintenance procedures. This additional exposure has resulted in fan disk focused inspection rates that exceed the intent of the focused inspection initiative.

DATES:

Comments for inclusion in the Rules Docket must be received on or before September 18, 2000.

ADDRESSES:

Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-49-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: “[e-mail]”. Comments sent via the Internet must contain the docket number in the subject line.

FOR FURTHER INFORMATION CONTACT:

Kevin Donovan, 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:

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 in triplicate 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 99-NE-44-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. 99-NE-44-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On February 7, 2000, the FAA issued AD 2000-03-03, Amendment 39-11560, (65 FR 5759) to require changes to the Engine Maintenance Program specified in the manufacturer's ICA for GE CF34 series turbofan engines. These changes required enhanced inspection of selected critical life-limited parts at each piece-part exposure and that an air carrier's approved continuous airworthiness maintenance program incorporate these inspection procedures. That action was prompted by an FAA study of in-service events involving uncontained failures of critical rotating engine parts, which indicated the need for improved inspections. The improved inspections are needed to identify those critical rotating parts with conditions that, if allowed to continue in service, could result in uncontained failures. If not corrected, that condition could result in engine rotating part failure, which could result in an uncontained engine failure and damage to the airplane.

Revised Inspection Requirements

Since AD 2000-03-03 was issued, the FAA has determined that, for piece-part exposures resulting from parts removed from an engine mounted on-wing in accordance with certain maintenance procedures, it is unnecessary to perform the inspection requirements listed in Table 804 of the GE CF34 series turbofan Engine Manual. Performing the enhanced inspections each time the disk is exposed on-wing does not significantly add to the probability of detection of defects. The FAA has concluded that inspection at every opportunity for this model engine is not necessary to maintain the level of safety intended by the current AD.

Since an unsafe condition has been identified that is likely to exist or develop on other GE CF34 engines of the same type design, the proposed AD would revise AD 2000-03-03 to change the mandatory inspection requirements to relieve parts removed from engines mounted on-wing from the inspection requirements of Table 804.

Regulatory Impact

The proposed revision would not increase the economic burden on US operators as set out in the economic analysis published for the current AD.

The regulations adopted herein will 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

The FAA has determined that this regulation is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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

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:

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 39-11560 (65 FR 5759, February 7, 2000), and by adding a new airworthiness directive, to read as follows:

General Electric Company: Docket 99-NE-49 AD. Revises AD 2000-03-03, Amendment 39-11560.

Applicability: General Electric Company (GE) CF34-3A1 and -3B1 series turbofan engines, installed on but not limited to Bombardier Canadair CL601R (RJ) aircraft.

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: 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 CF34 Engine Maintenance Program, Chapter 5-21-00, of the GE CF34 Series Turbofan Engine Manual, SEI-756, and for air carrier operations revise the approved continuous airworthiness maintenance program, by adding the following:

“9. CF34-3A1 and CF34-3B1 Engine Maintenance Program —Mandatory Inspection Requirements.

(A) This procedure is used to identify specific piece-parts that require mandatory inspections that must be accomplished at each piece-part exposure using the applicable Chapters referenced in Table 804 for the inspection requirements. The inspection requirements listed in Table 804 are not required for any piece-part exposure resulting when the engine remains on-wing while performing maintenance practice, special procedure Number 41 listed in SEI-756, chapter 72-00-00, or from Alert Service Bulletin 72-A0103_R00.

(B) Piece-part exposure is defined as follows: Note: Fan disk piece-part includes the fan disk with the 56 fan pin bushings installed.

(1) For engines that utilize the “On Condition” maintenance requirements: The part is considered completely disassembled to the piece-part level when done in accordance with the disassembly instructions in the GEAE authorized overhaul Engine Manual, and 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.

(2) For engines that utilize the “Hard Time” maintenance requirements: The part is considered completely disassembled when done in accordance with the disassembly instructions used in the “Minor Maintenance” or “Overhaul” instructions in the GEAE engine authorized Engine Manual, and 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.

C. Refer to Table 804 below for the mandatory inspection requirements.

Table 804.—Mandatory Inspection Requirements

Part nomenclature	Manual/chapter, section/subject	Mandatory, inspection
Fan Disk (all)	72-21-00, INSPECTION	All areas (FPI) 1 Bores (ECI) 2
Stage 1 high pressure turbine (HPT) Rotor Disk (all) (FPI)1	72-46-00, INSPECTION	All areas Bores (ECI) 2 Boltholes (ECI) 2 Air Holes (ECI) 2
Stage 2 HPT Rotor Disk (all)	72-46-00, INSPECTION	All Areas (FPI) 1 Bores (ECI) 2
(a) Boltless Rim Configuration		Boltholes (FPI) 1 Air Holes (FPI) 1
(b) Bolted Rim Configuration		Boltholes (ECI) 2 Air Holes (ECI) 2
HPT Rotor Outer Torque Coupling (all)	72-46-00, INSPECTION	All areas (FPI) 1 Bore (ECI) 2
1 FPI=Fluorescent Penetrant Inspection Method
2 ECI=Eddy Current Inspection

(b) Except as provided in paragraph (c) of this AD, and notwithstanding the provisions of section 43.16 of the Federal Aviation Regulations (14 CFR 43.16), these mandatory inspections shall be performed only in accordance with the CF34 Engine Maintenance Program, Chapter 5-21-00, of the General Electric Company, CF34 Series Turbofan Engine Manual, SEI-756.

Alternative Method 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 shall submit their requests through an appropriate FAA Principal Maintenance Inspector (PMI), 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 AD, if any, may be obtained from the ECO.

Special Flight Permits

(d) 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 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 CF34 Engine Maintenance Program 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 engine manual changes are made and air carriers have modified their continuous airworthiness maintenance plans to reflect the Engine Maintenance Program requirements specified in the GE CF34 Series Turbofan Engine Manual.

Issued in Burlington, Massachusetts, on August 11, 2000.

David A. Downey,

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