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Proposed Rule

Airworthiness Directives; Boeing Model 747-400, -400D, and -400F Series Airplanes Equipped With General Electric (GE) or Pratt & Whitney (P&W) Series Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 747-400, -400D, and -400F series airplanes; equipped with GE or P&W series engines, that would have required modifications and functional tests of the wiring of the wire integration unit and the air supply control test unit (ASCTU) of the engine Start Printed Page 50342bleed air distribution system. This new action revises the proposed rule by adding a new requirement. The actions specified by this new proposed AD are intended to prevent inadvertent commanded shutdown of the engine bleed air distribution systems due to an erroneous ASCTU command. That shutdown could cause depressurization of the airplane and subsequent ice build-up on the engine inlets during descent, which could result in ingestion of ice into the engine(s) and consequent loss of thrust on one or more engines. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by September 10, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-173-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-173-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Don Eiford, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6465; fax (425) 917-6590.

End Further Info End Preamble Start Supplemental Information

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 shall 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 action may be changed in light of the comments received.

Submit comments using the following format:

  • Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
  • For each issue, state what specific change to the proposed AD is being requested.
  • Include justification (e.g., reasons or data) for each request.

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 2002-NM-173-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, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-173-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Boeing Model 747-400, -400D, and -400F series airplanes; equipped with GE or P&W series engines, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on August 11, 2003 (68 FR 47513) (hereafter referred to as the “original NPRM.”) The original NPRM would have required modifications and functional tests of the wiring of the wire integration unit and the air supply control test unit (ASCTU) of the engine bleed air distribution system. The original NPRM was prompted by a report that, on two separate occasions, there was a loss of airflow from all four bleed air distribution systems that caused the ASCTU to indicate an erroneous strut overheat condition, and command shutdown of the bleed air distribution systems. Inadvertent commanded shutdown of the engine bleed air distribution systems due to an erroneous ASCTU command, could cause depressurization of the airplane and subsequent ice build-up on the engine inlets during descent, which could result in ingestion of ice into the engine(s) and consequent loss of thrust on one or more engines

Comments

We have considered the following comments on the original NPRM.

Request To Reduce Compliance Time

One commenter states that a compliance time of 18 months for the modifications and functional tests of the wiring of the wire integration unit and the ASTCU command, as specified in the original NPRM, is too lengthy, and notes that these actions should be done in a more timely manner. The commenter notes that industry has been aware of the condition since the issuance of Boeing Service Bulletin 747-36A2136, dated April 12, 2001 (Revision 1, dated January 17, 2002, was referenced in the original NPRM for accomplishing the specified actions), and adds that the actions take only 8 hours to do. For these reasons, the commenter states that the remaining fleet can be modified within 6 to 9 months. In addition, the commenter states that failure of the identified system poses a significant safety risk should an erroneous ASCTU command and subsequent inadvertent commanded shutdown of the pressurization and de-icing/anti-icing systems occur. Such failure on polar or oceanic routes where the need to divert to distant airports can lead to extended flight in adverse conditions such as icing, low altitude weather, and cold temperatures may be unavoidable. The commenter asks that accomplishment of the actions specified in the original NPRM be done in a more timely manner.

We do not agree. In developing an appropriate compliance time for the modifications and functional tests, we considered the safety implications and normal maintenance schedules for timely accomplishment of the actions. Further, we arrived at the compliance time with operator and manufacturer concurrence. In consideration of these factors, and because the amount of time required for doing the modifications and functional tests is sufficiently long, we determined that the compliance time, as proposed, represents an appropriate interval in which the actions can be accomplished in a timely manner, while Start Printed Page 50343still maintaining an adequate level of safety. Operators are always permitted to do the requirements of an AD at a time earlier than the specified compliance time; therefore, an operator may choose to do the modifications and functional tests before the compliance time. If additional data are presented that would justify a shorter compliance time, we may consider further rulemaking on this issue. No change to the supplemental NPRM is made in this regard.

Request To Confirm Proper Sequence for Modifications/Tests

One commenter asks for FAA confirmation that it is acceptable to do the resistance tests specified in paragraph (a)(3) of the original NPRM before removing the existing ASCTU and installing a new or reworked ASCTU, as specified in paragraph (a)(2) of the original NPRM. The commenter also asks for confirmation that it is acceptable to do the post-installation tests specified in paragraph (a)(3) after doing the removal and installation specified in paragraph (a)(2).

In response to the commenter's request, we contacted Boeing to verify the proper sequence for doing the modifications and functional tests. Boeing verified that the commenter is correct in that the resistance tests should be done without the ASCTU installed; therefore, Boeing has issued, and we have reviewed, Boeing Service Bulletin 747-36A2136, Revision 2, dated May 13, 2004, to incorporate the proper sequence. The procedures specified in Revision 2 are essentially the same as those in Revision 1. However, the procedures in Revision 2 change the sequence of the work steps to specify doing the resistance test after the ASCTU is removed. Therefore, we have revised paragraph (a) of the supplemental NPRM by changing the sequence for doing the modifications and functional tests, and adding Revision 2 of the service bulletin as the appropriate source of service information for accomplishing those actions. In addition, we have changed paragraph (b) of the supplemental NPRM to specify that if the resistance test was done with the ASCTU installed, using the original issue or Revision 1 of the service bulletin, the ASCTU must be removed and the test done again within 18 months after the effective date of this AD.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

The change discussed above expands the scope of the original NPRM; therefore, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment on this supplemental NPRM. This supplemental NPRM would require doing the resistance test again if the test was done with the ASCTU installed.

Cost Impact

There are approximately 414 airplanes of the affected design in the worldwide fleet. The FAA estimates that 70 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 8 work hours per airplane to accomplish the proposed modifications and functional tests, and that the average labor rate is $65 per work hour. Required parts would be minimal. Based on these figures, the cost impact of the proposed actions on U.S. operators is estimated to be $36,400, or $520 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

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.

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List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

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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[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2002-NM-173-AD.

Applicability: Model 747-400, -400D, and -400F series airplanes; as listed in Boeing Service Bulletin 747-36A2136, Revision 2, dated May 13, 2004; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent inadvertent commanded shutdown of the engine bleed air distribution systems due to an erroneous air supply control test unit (ASCTU) command, which could cause depressurization of the airplane and subsequent ice build-up on the engine inlets during descent, which could result in ingestion of ice into the engine(s) and consequent loss of thrust on one or more engines, accomplish the following:

Modifications/Tests

(a) Within 18 months after the effective date of this AD: Do the modifications and functional tests of the wiring of the wire integration unit (WIU) and the ASCTU of the engine bleed air distribution system specified in paragraphs (a)(1), (a)(2), (a)(3), (a)(4) of this AD, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-36A2136, Revision 2, dated May 13, 2004. Before further flight after accomplishing paragraphs (a)(2), (a)(3), and (a)(4) of this AD: Do the post-installation tests in accordance with the service bulletin.

(1) Remove the existing ASCTU.

(2) Do the wiring changes between the WIU and ASCTU and the wiring changes to the WIU.

(3) Do the resistance tests.

(4) Install a new or reworked ASCTU.

Credit for Previous Issues of Boeing Service Bulletin

(b) Modifications and tests accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-36A2136, dated April 12, 2001; or Revision 1, dated January 17, 2002; are considered acceptable for compliance with Start Printed Page 50344the corresponding actions specified in paragraph (a) of this AD, if the resistance tests were done with the ASCTU removed. If the resistance tests were done with the ASCTU installed, do the actions specified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD, at the time specified in paragraph (a) of this AD, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-36A2136, Revision 2, dated May 13, 2004. Before further flight after accomplishing paragraph (b)(3) of this AD: Do the post-installation tests in accordance with the service bulletin.

(1) Remove the existing ASCTU.

(2) Do the resistance tests.

(3) Reinstall the ASCTU.

Part Installation

(c) As of the effective date of this AD, no person may install on any airplane an ASCTU having a part number listed in the “Old Part Number” column in the table specified in paragraph 3.C. of the Accomplishment Instructions of Hamilton Sundstrand Service Bulletin 36-186, dated March 30, 2001.

Alternative Methods of Compliance (AMOCs)

(d) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Start Signature

Issued in Renton, Washington, on August 9, 2004.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 04-18641 Filed 8-13-04; 8:45 am]

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