AD 99-23-26

This amendment supersedes an existing airworthiness directive (AD), applicable to General Electric Aircraft Engines (GE) CF34 series turbofan engines, that currently requires installation of a main fuel control (MFC) that incorporates a flange vent groove and installation of an MFC with improved overspeed protection. This amendment requires replacement of Buna-N O-rings with Viton O-rings or a new location of the vent groove on the MFC mounting flange, or installation of an MFC with improved overspeed protection. This amendment is prompted by the determination that the location of the reworked vent groove was ineffective, and that replacement of Buna-N preformed packings with Viton preformed packings will alleviate the unsafe condition. The actions specified by this AD are intended to prevent uncommanded engine accelerations, which could result in an engine overspeed, uncontained engine failure, and damage to the airplane.

The incorporation by reference of GE Alert ServiceBulletins (ASB s) No. A73-33, dated November 21, 1997; A73-33, Revision 1, dated May 29.1998; and A73-19, Revision 1, dated February 20, 1998, was approved by the Director of the Federal Register as of July 27, 1999.

The incorporation by reference of GE ASB No. CF34AL 73-A0025, dated July 7, 1999; CF34BJ 73-A0040, dated July 7, 1999; CF34AL S/B 73-0026, dated August 12, 1999; and CF34BJ S/B 73-0041, dated August 12,1999, is approved by the Director of the Federal Register as of December 6, 1999.

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

Final rule; request for comments.

99-23-26 GENERAL ELECTRIC: Amendment 39-11422; Docket 98-ANE-19-AD. Supersedes AD 99-11-08, Amendment 39-11179.

Applicability: General Electric (GE) CF34-1A, CF34-3A, -3A1, -3A2, and CF34-3B and -3B1 series turbofan engines, installed on but not limited to Bombardier, Inc. Canadair airplane models CL-600-2A12, -2B16, and -2B19.

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 (f) 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 uncommanded engine accelerations, which could result in an engine overspeed, uncontained engine failure, and damage to the airplane, accomplish the following:

Replacement Requirements

(a) If the main fuel control (MFC) part numbers (P/N's) 6078T55P02, 6078T55P03, 6078T55P04, 6078T55P05, 6078T55P06, 6078T55P07, 6078T55P08, 6078T55P09, 6078T55P10, 6078T55P12, 6078T55P13, 6078T55P14, 6078T55P15, or 6078T55P16 installed, and if the MFC has Buna-N preformed packings (O-rings), P/N's R1307P020 and R1307P141, do one of the following:

(1) Replace Buna-N O-rings with Viton O-rings, P/N's M83485-1-020 (M83485/1-020) and 37B201714P130, within 30 days after the effective date of this AD, in accordance with the Accomplishment Instructions, paragraph 3.A., of alert service bulletin (ASB) CF34AL 73-A0025, dated July 7, 1999 or ASB CF34BJ 73-A0040, dated July 7, 1999. or,

(2) For all CF34-3A1 engines with serial numbers (SN's) 807001 and up, CF34-3B engines with SN's 872001 and up, and CF34-3B1 engines with SN's 872001 and up, with main fuel control (MFC) part numbers (P/N's) 6078T55P02, 6078T55P03, 6078T55P04, 6078T55P05, 6078T55P06, 6078T55P07, 6078T55P08, 6078T55P09, 6078T55P10, 6078T55P12, 6078T55P13, 6078T55P14, 6078T55P15, or 6078T55P16 installed, within 30 days after the effective date of this AD, install an MFC with a flange vent groove that conforms to the requirements of CF34 ASB CF34AL S/B 73-0026, dated August 12,1999, or CF34BJ S/B 73-0041, dated August 12,1999.

Replacement of the MFC

(b) For all CF34-1A, -3A, and -3A2 series engines with SN's 350003 through 350525, install an MFC with a flange groove that conforms to the requirements of CF34 ASB CF34AL S/B 73-0026, dated August 12,1999, the next time the engine is removed or the next time the MFC is removed.

(c) Install a serviceable MFC with improved overspeed protection as follows:

(1) For all CF34-1A, -3A, and -3A2 series engines, install a serviceable MFC at the next hot section inspection, or within 53 months after the effective date of this AD, whichever occurs first, in accordance with step 2A through step 2G of the Accomplishment Instructions of CF34 ASB No. A73-33, dated November 21, 1997, or Revision 1, dated May 29, 1998.

(2) For CF34-3A1, and -3B series engines installed on Canadair aircraft models CL601 or CL604 (Challenger airplanes), install a serviceable MFC at the next hot section inspection, or within 53 months after the effective date of this AD, whichever occurs first, in accordance with step 2A through step 2G of the Accomplishment Instructions of CF34 ASB No. A73-33, dated November 21, 1997, or Revision 1, dated May 29, 1998.

(3) For CF34-3A1 and -3B1 series engines installed on Canadair aircraft model CL601RJ (Regional Jet airplanes), install a serviceable MFC within 4,000 hours TIS after the effective date of this AD, or within 17 months after the effective date of this AD, whichever occurs first, in accordance with step 2A through step 2G of the Accomplishment Instructions of CF34 ASB No. A73-19, Revision 1, dated February 20, 1998.

Terminating Action

(d) Replacing an MFC with a serviceable MFC, as defined in paragraph (e) of this AD, constitutes terminating action for the requirements of this AD.

Definition of a Serviceable MFC

(e) For the purposes of this AD, a serviceable MFC is defined as any MFC that incorporates the improved overspeed protection modifications, or an MFC that has been reworked to provide the improved overspeed protection as provided by the applicable GE ASB and is not one of the following P/N's 6078T55P02, 6078T55P03, 6078T55P04, 6078T55P05, 6078T55P06, 6078T55P07, 6078T55P08, 6078T55P09, 6078T55P10, 6078T55P12, 6078T55P13, 6078T55P14, 6078T55P15, 6078T55P16, 6047T74P11, 6047T74P12, or 6091T07P02.

Alternative Method of Compliance

(f) 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, 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

(g) 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.

Manufacturer Service Bulletins

(h) The inspection shall be done in accordance with the following GE service bulletins:

DocumentNo.
Pages
Revision
Date
CF34AL 73-A0025
All
Original
July 7, 1999
CF34AL 73-0026
All
Original
August 12,1999
CF34BJ 73-0040
All
Original
July 7,1999
CF34BJ 73-0041
All
Original
August 12,1999
A73-19
All
1
February 20, 1998
A73-33
All
Original
November 21, 1997
A73-33
All
1
May 29, 1998
Total pages: 27

(i) The incorporation by reference of GE ASB A73-19, dated February 20, 1998; ASB A73-33, dated November 21, 1997; and ASB A73-33, revision 1, dated May 29, 1998, was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of July 27, 1999.

Address for Obtaining Referenced Service Bulletins

(j) Copies may be obtained from GEAE Technical Publications, Attention: N. Hanna MZ340M2, 1000 Western Avenue, Lynn, MA 01910; telephone (781) 594-2906, fax (781) 594-0600. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC. Effective Date of This AD

(k) This amendment becomes effective on December 6, 1999.

On May 17, 1999, the Federal Aviation Administration (FAA) issued airworthiness directive (AD) 99-11-08, Amendment 39-11179 (64 FR 28905, May 28, 1999), to require, within 800 hours time in service (TIS) or 120 days after the effective date of that AD, whichever occurs first, installation of an MFC incorporating a flange vent groove. In addition, that AD requires installation of an MFC with improved overspeed protection for: CF34-3A1 and -3B1 series engines, installed on Canadair Regional Jet airplanes, within 4,000 hours TIS after the effective date of that AD, or 24 months after the effective date of that AD, whichever occurs first; and for CF34-1A, -3A, -3A1, -3A2, and -3B series engines, installed on Canadair Challenger airplanes, at the next hot section inspection, or within 60 months after the effective date of that AD, whichever occurs first. That action was prompted by reports of rapid uncommanded engine acceleration events. That condition, if not corrected, could result in uncommanded engine accelerations, which could result in an engine overspeed, uncontained engine failure, and damage to the airplane.

Events Leading to this AD

Since the issuance of that AD, the engine manufacturer has informed the FAA that GE CF34 Alert Service Bulletin (ASB) No. A73-18, Revision 1, dated September 24, 1997, and CF34 ASB No. A73-32, Revision 1, dated September 24, 1997, that describe procedures for reworking MFC s by adding a flange vent groove were in error and had incorrectly located the flange vent groove. Also, the manufacturer has determined that replacement of the Buna-N preformed packings (O-rings) with Viton O-rings will achieve a similar level of safety as the installation of an MFC with a correctly located flange vent groove.

Manufacturer Service Information

The FAA has reviewed and approved the technical contents of GE CF34 Alert Service Bulletins (ASB s) No. CF34AL 73-A0025, dated July 7, 1999, and CF34BJ 73-A0040, dated July 7, 1999, that describe procedures for replacement of the Buna-N preformed packings; CF34AL S/B 73-0026, dated August 12, 1999, and CF34BJ S/B 73-0041, dated August 12,1999, that describe procedures for installation of a reworked MFC with a relocated pressure relief groove; and CF34 ASB No. A73-19, Revision 1, dated February 20, 1998, and CF34 ASB No. A73-33, dated November 21, 1997, that describe procedures for installation of a reworked MFC with improved overspeed protection.

Differences Between the ASB s and this AD

The GE ASB s allow the MFC on CF34-1A, -3A1, and 3A2 engines to be used until the MFC is removed for cause and then replaced with an MFC with a relocated vent groove. Because of the possibility that an unsafe condition may develop, this AD requires that the MFC be replaced with an MFC with a relocated vent groove when the MFC is removed for any reason.

Requirements of this AD

Since an unsafe condition has been identified that is likely to exist or develop on other General Electric (GE) CF34 turbofan engines of the same type design, this AD supersedes AD 99-11-08 to require either replacement of Buna-N O-rings with Viton O-rings or replacement of the MFC with an MFC with a relocated vent groove within 30 days after the effective date of this AD. The actions are required to be accomplished in accordance with the service bulletin described previously.

Immediate Action

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Request for Comments

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 inthe 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 98-ANE-19-AD." The postcard will be date stamped and returned to the commenter.

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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and 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, 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 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]

2. Section 39.13 is amended by removing Amendment39-11179, (64 FR 28905, May 28, 1999), and by adding a new airworthiness directive, Amendment 39-11422, to read as follows: