[Federal Register: August 16, 2004 (Volume 69, Number 157)]
[Proposed Rules]
[Page 50341-50344]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16au04-26]
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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:
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.
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
[[Page 50343]]
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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