[Federal Register Volume 69, Number 157 (Monday, August 16, 2004)]
[Proposed Rules]
[Pages 50341-50344]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-18641]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-173-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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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

[[Page 50342]]

bleed 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: 
[email protected]. 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.

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.

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

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still 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.

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.


Sec.  39.13  [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

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the 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.

    Issued in Renton, Washington, on August 9, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-18641 Filed 8-13-04; 8:45 am]
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