01-14671. Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), applicable to certain General Electric Company (GE) GE90 series turbofan engines. That AD currently requires inspecting and purging the P3B and Ps3 lines and associated fittings and ports of moisture. This proposal would allow the installation of improved hardware as terminating action to requirements of the AD, and remove the GE90-92B engine model from the AD applicability. This proposal is prompted by the recent FAA approval of redesigned P3B and Ps3 sense lines, and the removal of the GE90-92B engine from the applicability. The actions described in this proposal are intended to prevent loss of thrust control due to corruption of the P3B and Ps3 signals to the FADEC, which if it occurs in a critical phase of flight, could result in loss of airplane control.

DATES:

Comments must be received by August 13, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-NE-62-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. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from General Electric Company via Lockheed Martin Technology Services, 10525 Chester Road, Suite C, Cincinnati, OH 45215; telephone: [phone], fax: [phone]. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

John E. Golinski, 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 to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before we take 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 sent 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 send a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NE-62-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. 99-NE-62-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On December 29, 1999, the FAA issued AD 99-27-15, Amendment 39-11496 (65 FR 692, January 6, 2000), to require visually inspecting P3B and Ps3 sense lines and FADEC P3B and Ps3 sensing ports and fittings, cleaning P3B and Ps3 fittings and sensing ports, purging the P3B and Ps3 systems of moisture, and, if necessary, blending of high metal, nicks, burrs, or scratches on P3B and Ps3 fitting threads. That action was prompted by seven reports of loss of thrust control due to corruption of the signals to the FADEC caused by water freezing in the Ps3 sensing system. That condition, if not corrected, could result in loss of thrust control due to corruption of the P3B and Ps3 signals to the FADEC, which if it occurs in a critical phase of flight, could result in loss of airplane control. Since that AD was issued, improved hardware has been introduced as terminating action to the visual inspections, cleanings, purging, and blending of metal. Also, alternative methods of compliance approved for AD 99-27-15 are incorporated as conventional methods of compliance in this proposal. Also, the GE90-92B engine model has been removed from the AD applicability. The FAA recently removed the GE90-92B engine from the type certificate at the request of GE.

Service Information

The FAA has reviewed and approved the technical contents of GE Alert Service Bulletin (ASB) GE90 73-A0060, Revision 3, dated September 14, 2000, that describes procedures for:

• Visually inspecting P3B and Ps3 sense lines and FADEC sensing ports and fittings.
• Cleaning P3B and Ps3 fittings and sensor ports, purging the P3B and Ps3 systems of moisture.
• Blending of high metal, nicks, burrs, or scratches on Ps3 and P3B fitting threads.

The FAA has also reviewed and approved the technical contents of GE Service Bulletin (SB) GE90 S/B 75-0031, Revision 3, dated March 30, 2001, that describes procedures for replacing existing P3B and Ps3 lines and related brackets and clamping with redesigned hardware.

Differences Between ASB, SB, and Proposal

This proposal contains provisions for initial actions and GE ASB GE90 73-A0060, Revision 3, dated September 14, 2000, assumes that all operators have completed the initial actions based on field reports. If, however, operators have already accomplished the required initial actions, they need not repeat those actions, but may proceed directly to accomplishing the repetitive actions, or P3B and Ps3 line replacement. Also, GE SB GE90 S/B 75-0031, Revision 3, dated March 30, 2001, recommends a hardware installation date of not later than March 31, 2001, and this proposal requires hardware installation at the next shop visit after the effective date of this AD, or no later than October 31, 2001. The FAA is aware that almost all affected GE90 engines have been retrofitted with the new design hardware and, therefore, has established this end date of not later than October 31, 2001, to complete the retrofit program before the colder temperatures of winter arrive.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other engines of the same type design, this proposed AD would supersede AD 99-27-15, to require:

• Visual inspections for high metal, nicks, burrs, or scratches on P3B and Ps3 fitting threads, and, if necessary, blending of these.
• Visual inspections for moisture, debris, or ice in P3B and Ps3 FADEC fittings, ports, and open sense lines.
• Cleaning of P3B and Ps3 FADEC fittings and sensing ports.
• Purging of any moisture from the P3B and Ps3 sense system.
• Replacement of existing P3B and Ps3 lines and related brackets and clamping with redesigned hardware at the next shop visit after the effective date of this AD, or no later than October 31, 2001.
• Engine idle leak check run following the maintenance activity to confirm there are no P3B or Ps3 sense system faults present, or a dual signoff procedure by a 2nd mechanic.

Economic Impact

There are about 208 engines of the affected design in the worldwide fleet. The FAA estimates that 28 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take about one work hour per engine to do the proposed inspection and purging, and that the average labor rate is $60 per work hour. Based on these figures, the total proposed AD cost impact on U.S. operators for one inspection is estimated to be $1,680. The FAA also estimates that it would take about four work hours per engine to do the proposed P3B/Ps3 sense line replacement, and that the average labor rate is $60 per work hour. The manufacturer has stated that it may provide the redesigned hardware at no cost to operators. Based on this information, the total proposed AD cost impact on U.S. operators for sense line replacement is estimated to be $6,720.

Regulatory Impact

This proposal 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 before publication of this proposal.

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

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration (FAA) 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 39-11496 (65 FR 692, January 6, 2000) and by adding a new airworthiness directive:

General Electric Company: Docket No. 99-NE-62-AD.

Applicability: General Electric Company (GE) Models GE90-76B, -77B, -85B, and -90B turbofan engines. These engines are installed on, but not limited to Boeing 777 series airplanes.

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 (m) 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 the requirements of this AD is required as indicated, unless already done.

To prevent loss of thrust control due to corruption of the P3B and Ps3 signals to the full authority digital engine control (FADEC), which if it occurs in a critical phase of flight, could result in loss of airplane control, do the following:

Determination of Further Action

(a) If the engine has been configured as specified in one of the following service bulletins (SB's), or has one of the following serial numbers (SN's), no further action is required.

(1) SB GE90 S/B 75-0031, Revision 1, dated August 29, 2000.

(2) SB GE90 S/B 75-0031, Revision 2, dated September 14, 2000.

(3) SB GE90 S/B 75-0031, Revision 3, dated March 30, 2001.

(4) Engine SN is 900-326, 900-328, 900-332, 900-333, 900-334, or higher.

Initial Inspection, Cleaning, Moisture Purging, and Blending

(b) For engines that are not configured or listed by SN as specified in paragraph (a) of this AD, do the following:

(1) Inspect, clean, moisture purge, and if necessary, blend any high metal, nicks, or burrs on fitting threads, on one engine installed on Boeing 777 series aircraft, within 10 cycles-in-service (CIS) after the effective date of this AD in accordance with the Accomplishment Instructions, Section 3 of GE Alert Service Bulletin (ASB) No. GE90 73-A0060, Revision 3, dated September 14, 2000.

(2) Inspect, clean, moisture purge, and if necessary, blend any high metal, nicks, or burrs on fitting threads, on the other engine installed on the Boeing 777 series aircraft, within 20 CIS after the effective date of this AD in accordance with the Accomplishment Instructions, Section 3 of GE ASB No. GE90 73-A0060, Revision 3, dated September 14, 2000.

Credit for Previous Inspections, Cleaning, and Moisture Purging

(c) For engines that have complied with the initial and repetitive inspections of AD 99-27-15, GE ASB No. GE90 73-A0060, Revision 1, dated March 1, 2000; GE ASB No. GE90 73-A0060, Revision 2, dated May 12, 2000; GE ASB No. GE90 73-A0060, Revision 3, dated September 14, 2000; or with an FAA approved alternative method of compliance, perform repetitive inspections as specified in paragraph (d) of this AD.

Repetitive Inspections

(d) Thereafter, inspect, clean, and moisture purge, and if necessary, blend any high metal, nicks, or burrs on fitting threads of each engine in accordance with the Accomplishment Instructions, Section 3, of GE ASB No. GE90 73-A0060, Revision 3, dated September 14, 2000, within:

(1) 30 CIS since-last-inspection, or,

(2) If applicable, 125 CIS since-last-inspection for one-engine-only per airplane.

Replacement Engines

(e) For replacement engines, perform the initial inspection, cleaning, and moisture purging, and if necessary, blend any high metal, nicks, or burrs on fitting threads as specified in paragraph (b) of this AD, except perform initial inspection before accumulating 30 CIS or 125 CIS, depending on the existing inspection interval for the engine that was replaced.

Idle Leak Check or Dual Signoff Procedure Check

(f) After accomplishing the inspection and maintenance actions specified in paragraphs (b) through (e) of this AD, and before entry into service, do either of the following:

(1) Perform an idle leak check to confirm no P3B or Ps3 sense system faults in accordance with Accomplishment Instructions, Section 3, paragraph (15), of GE ASB No. GE90 73-A0060, Revision 3, dated September 14, 2000. or,

(2) Perform a dual signoff procedure check to confirm there are no loose fittings that could cause P3B and Ps3 sense system faults, in accordance with Accomplishment Instructions, Section 3, paragraph (15), of GE ASB No. GE90 73-A0060, Revision 3, dated September 14, 2000. Idle leak checks that were performed using GE ASB No. GE90 73-A0060, dated December 23, 1999, and idle leak checks or dual signoff procedure checks that were performed using GE ASB No. GE90 73-A0060, Revision 1, dated March 1, 2000, or GE ASB No. GE90 73-A0060, Revision 2, dated May 12, 2000, may be considered as alternative methods of compliance for this requirement.

Installation of Redesigned Hardware

(g) At the next engine shop visit after the effective date of this AD, but not later than October 31, 2001, install the redesigned P3B and Ps3 tubes, hoses, clamps, and bracket assembly in accordance with Accomplishment Instructions, Section 3.A. through 3.H. of GE ASB No. GE90 S/B 75-0031, Revision 3, dated March 30, 2001.

Definition

(h) For the purposes of this AD, an engine shop visit is defined as any time an engine has maintenance performed that involves separation of a major flange, such as removal of the low pressure turbine module, or high pressure compressor top case half.

Credit for Installation of Redesigned Hardware

(i) Hardware installation that was performed using GE ASB No. GE90 S/B 75-0031, Revision 2, dated September 14, 2000; or GE ASB No. GE90 S/B 75-0031, Revision 1, dated August 29, 2000, may be considered as alternative methods of compliance for this requirement.

No Simultaneous Actions

(j) Do not perform the actions required by this AD concurrently on both engines installed on Boeing 777 series aircraft.

Old Configuration Hardware

(k) After the effective date of this AD, do not install any of the old configuration hardware listed in the following table.

Old Configuration Hardware Not To Be Installed

Part	Part No.
Ps3 Tube	350-151-505-0 350-184-806-0 350-114-005-0
Ps3 Hose	649-794-573-0
P3B Tube	350-151-604-0 350-184-904-0 350-114-105-0
P3B Hose	649-794-572-0
Single Tube Clamp	2151M51P107
Double Tube Clamp	2151M52P102
Bracket Assembly	350-178-309-0 350-178-311-0

Terminating Action

(l) Installation of redesigned hardware as specified in paragraph (g) of this AD constitutes terminating action for requirements of paragraph (d) and paragraph (e) of this AD.

Alternative Methods of Compliance

(m) 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

(n) 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.

Issued in Burlington, Massachusetts, on June 4, 2001.

Francis A. Favara,

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