Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines

Summary:

The FAA proposes to supersede an existing airworthiness directive (AD), which is applicable to General Electric Company (GE) GE90 series turbofan engines. That AD currently requires revisions to the Life Limits Section of the manufacturer's Instructions for Continued Airworthiness (ICA) to include required enhanced inspection of selected critical life-limited parts at each piece-part exposure. This proposal would modify the airworthiness limitations section of the manufacturer's manual and an air carrier's approved continuous airworthiness maintenance program to incorporate additional inspection requirements. A Federal Aviation Administration (FAA) study of in-service events involving uncontained failures of critical rotating engine parts has indicated the need for mandatory inspections. The mandatory inspections are needed to identify those critical rotating parts with conditions, which if allowed to continue in service, could result in uncontained failures. This proposal is prompted by additional focused inspection procedures that have been developed by the manufacturer. The actions specified by this proposed AD are intended to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.

Table of Contents

Addresses:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-39-AD, 12 New England Executive Park, Burlington, MA 01803-5299. 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. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

For further information contact:

Ian Dargin, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7178, fax (781) 238-7199.

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 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 action 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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 98-ANE-39-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

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. 98-ANE-39-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On April 14, 2000, the FAA issued AD 2000-08-10, Amendment 39'11696 (65 FR 21642, April 24, 2000), to require revisions to the Life Limits Section of the manufacturer's Instructions for Continued Airworthiness (ICA) for GE GE90 series turbofan engines to include required inspection of selected critical life-limited parts at each piece-part exposure.

Additional Inspection Procedures

Since that AD was issued, an FAA study of in-service events involving uncontained failures of critical rotating engine parts has indicated the need for additional mandatory inspections. The mandatory inspections are needed to identify those critical rotating parts with conditions, which if allowed to continue in service, could result in uncontained failures. This proposal would modify the airworthiness limitations section of the manufacturer's manual and an air carrier's approved continuous airworthiness maintenance program to incorporate additional inspection requirements.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 2000-08-10 to add additional critical life-limited parts for enhanced inspection at each piece-part opportunity.

This proposed AD would also delete the GE90-92B model from the applicability and add recently certified engine model, the GE 90-94B. Reference to the GE90-92B model is removed from the AD applicability because the manufacturer has informed the FAA that no engines of that model were produced and has requested that the FAA remove this model designation.

Economic Analysis

The FAA estimates that 31 engines installed on airplanes of US registry would be affected by this proposed AD, that it would take approximately 172 work hours per engine to accomplish the proposed new inspections, and that the average labor rate is $60 per work hour for a total approximate cost of $10320 per engine. It is further estimated that there will be about 34 shop visits per year that result in piece-part exposure of the additional affected components. Based on these figures, the total cost impact of the additional inspections that will be mandated by this proposed AD on U.S. operators is estimated to be $350880.

Regulatory Impact

This proposed 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 proposed rule.

For the reasons discussed above, I certify that this proposed regulation (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) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action 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.

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

2. Section 39.13 is amended by removing Amendment 39-11696 (65 FR 21642, April 24, 2000), and by adding a new airworthiness directive, to read as follows:

General Electric Company: Docket No. 98-ANE-39-AD. Supersedes AD 2000-08-10, Amendment 39-11696.

Applicability

This airworthiness directive (AD) is applicable to General Electric Company (GE) GE90-76B/ -77B/ -85B/ -90B/ -94B series turbofan engines. These engines are installed on but not limited to Boeing 777 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 (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 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 manufacturer's Life Limits Section of the Instructions for Continued Airworthiness (ICA), and for air carrier operations revise the approved continuous airworthiness maintenance program, by adding the following:

MANDATORY INSPECTIONS

(1) Perform inspections of the following parts at each piece-part opportunity in accordance with the instructions provided in the applicable manual provisions:

Part nomenclaturePart No. (P/N)Inspect per engine manual chapter
For GE90 Engines:
HPCR Disk, Stage 1 All 72-31-05-200-001-001 Fluorescent Penetrant Inspection (subtask 72-31-05-230-051), and 72-31-05-200-001-001 Eddy Current Inspection of the Bore, and 72-31-05-200-001-001 Eddy CurrentInspection of the Dovetail Slots.
HPCR Spool, Stage 2-6 All 72-31-06-200-001-001 Fluorescent Penetrant Inspection (subtask 72-31-06-230-051), and 72-31-06-200-001-001 Eddy Current Inspection of the S2 Dovetail Slots.
HPCR, Disk, Stage 7 All 72-31-07-200-001-001 Fluorescent Penetrant Inspection (subtask 72-31-07-230-051), and 72-31-07-200-001-001 Eddy Current Inspection (subtask 72-31-07-250-051 or 72-31-07-230-052 or 72-31-07-230-053.
HPCR Spool, Stage 8-10 All 72-31-08-200-001-001 Fluorescent Penetrant Inspection and 72-31-08-800-001 Eddy Current Inspection of the stage 8-9 inertia weld.
HPCR Seal, Compressor Discharge Pressure All 72-31-09-200-001-001 Fluorescent Penetrant Inspection (subtask 72-31-09-230-051), and 72-31-09-200-001-001 Eddy Current Inspection of the Boltholes.
HPCR Ring, Tube Supporter All 72-31-10-200-001-001 Fluorescent Penetrant Inspection.
HPTR, Interstage Seal All 72-53-03-200-001-001 Fluorescent Penetrant Inspection (subtask 72-53-03-230-053), and 72-53-03-200-001-001 Eddy Current Inspection of the Bore.
Fan Disk, Stage 1 All 72-21-03-200-001-001 Fluorescent Penetrant Inspection (subtask 72-21-03-230-051), and 72-21-03-200-001-001 Eddy Current, and 72-21-03-200-001-001 Ultrasonic Inspection of Dovetail Slots.
HPTR Disk, Stage 1 All 72-53-02-200-001-002 Fluorescent Penetrant Inspection (subtask 72-53-02-160-051), and 72-53-02-200-001-002 Eddy Current Inspection of the Bore.
HPTR Disk, Stage 2 All 72-53-04-200-001-004 Fluorescent Penetrant Inspection (subtask 72-53-04-230-052), and 72-53-04-200-001-004 Eddy Current Inspection of the Bore.
LPTR Cone Shaft All 72-56-07-200-001-001 Fluorescent Penetrant Inspection.
LPTR Fan Mid Shaft All 72-58-01-200-001-001 Magnetic Particle Inspection.
LPTR Disk, Stage 1 All 72-56-02-200-001-001 Fluorescent Penetrant Inspection.
LPTR Disk, Stage 2 All 72-56-02-200-001-001 Fluorescent Penetrant Inspection.
LPTR Disk, Stage 3 All 72-56-02-200-001-001 Fluorescent Penetrant Inspection.
LPTR Disk, Stage 4 All 72-56-02-200-001-001 Fluorescent Penetrant Inspection.
LPTR Disk, Stage 5 All 72-56-02-200-001-001 Fluorescent Penetrant Inspection.
LPTR Disk, Stage 6 All 72-56-02-200-001-001 Fluorescent PenetrantInspection.
Fan Shaft, Forward All 72-22-01-200-001-001 Fluorescent Penetrant Inspection.

(2) For the purposes of these mandatory inspections, piece-part opportunity means:

(i) The part is considered completely disassembled when accomplished in accordance with the disassembly instructions in the manufacturer's engine manual; and

(ii) 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.”

(b) Except as provided in paragraph (c) of this AD, and notwithstanding contrary provisions in section 43.16 of the Federal Aviation Regulations (14 CFR 43.16), these mandatory inspections must be performed only in accordance with the Life Limits Section of the manufacturer's ICA.

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 Engine Certification Office (ECO). Operators must submit their requests through an appropriate FAA Principal Maintenance Inspector (PMI), who may add comments and then send it to the 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

(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 recordkeeping requirement of § 121.369(c) of the Federal Aviation Regulations [14 CFR 121.369(c)] of this chapter must maintain records of the mandatory inspections that result from revising the Life Limits Section of the ICA and the air carrier's continuous airworthiness program. Alternatively, 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 requirements in the engine manuals.

Issued in Burlington, Massachusetts, on September 26, 2001. Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.

Loading most recent entriesloading

Feedback