[Federal Register Volume 70, Number 4 (Thursday, January 6, 2005)]
[Proposed Rules]
[Pages 1211-1215]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-286]


 ========================================================================
 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 70, No. 4 / Thursday, January 6, 2005 / 
Proposed Rules  

[[Page 1211]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-360-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400, 777-200, and 777-
300 Series Airplanes

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, 777-200, 
and 777-300 series airplanes, that would have required, for certain 
airplanes, replacement of the cell stack of the flight deck humidifier 
with a supplier-tested cell stack, or replacement with an end plate and 
subsequent deactivation of the flight deck humidifier. For other 
airplanes, that proposed AD would have required replacement of the cell 
stack with a blanking plate or a new cell stack, or replacement of the 
blanking plate with a supplier-tested cell stack. This new action 
revises the proposed AD by adding airplanes to the applicability; 
adding new inspections to determine certain part numbers; requiring 
replacement of the blanking plate with a supplier-tested cell stack if 
necessary; and changing certain words to clarify the intent of the 
proposed AD. The actions specified by this new proposed AD are intended 
to prevent an increased pressure drop across the humidifier and 
consequent reduced airflow to the flight deck, which could result in 
the inability to clear any smoke that might appear in the flight deck. 
This action is intended to address the identified unsafe condition.

DATES: Comments must be received by January 31, 2005.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-360-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. 2000-NM-360-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, PO 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: Jeffrey S. Palmer, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 917-6481; 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 2000-NM-360-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. 2000-NM-360-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, 777-200, and 777-300 series airplanes, 
was published as a notice of proposed rulemaking (NPRM) (hereafter 
referred to as the ``original NPRM'') in the Federal Register on 
September 19, 2003 (68 FR 54874). The original NPRM would have 
required, for certain airplanes, replacement of the cell stack of the 
flight deck humidifier with a supplier-tested cell stack, or 
replacement with an end plate and subsequent deactivation of the flight 
deck humidifier. The original NPRM also would have required, for other 
airplanes, replacement of the cell stack with a blanking plate or a new 
cell stack, or replacement of the blanking plate with a supplier-tested 
cell stack. The original NPRM was prompted by reports of sagging cell 
stack membranes of the flight deck humidifiers. That condition, if not 
corrected, could result in the

[[Page 1212]]

inability to clear any smoke that might appear in the flight deck.

Comments

    Due consideration has been given to the comments received in 
response to the original NPRM. Some of the comments, as discussed 
below, have resulted in changes to the original NPRM.

Request To Withdraw the Proposed AD

    One commenter, the parts manufacturer, requests that the proposed 
AD be withdrawn. The commenter contends that all affected humidifiers 
have been screened for the suspect cell stacks. The commenter also 
notes that it had no ability to track some of the cell stack serial 
numbers.
    The FAA does not agree to withdraw the proposed AD. We have not 
received confirmation that all Model 747-400, 777-200, 777-300 series 
airplanes equipped with Hamilton Sundstrand flight deck humidifiers 
have been screened for the suspect cell stacks. Even if the airplanes 
specified in Boeing Alert Service Bulletin 747-21-A2414, Revision 1, 
dated October 26, 2000, and Boeing Service Bulletin 777-21A0048, 
Revision 1, dated September 7, 2000 (referenced as the appropriate 
sources of service information for accomplishing the proposed actions), 
were verified not to have a defective cell stack, a defective cell 
stack could have been installed on certain other airplanes with a 
Hamilton Sundstrand humidifier. If an airplane not listed in the 
service bulletin was originally delivered with an acceptable cell 
stack, it is possible that, through maintenance or replacement actions, 
a defective cell stack could have been installed on any Model 747-400, 
777-200, or 777-300 airplane with a Hamilton Sundstrand humidifier 
having part number (P/N) 821486-1 or P/N 816086-1.
    Based on further review, we have determined that there were 
approximately 100 flight deck humidifiers produced with the defective 
cell stack and that 114 airplanes could be fitted with the defective 
cell stack.
    Due to the possibility that a defective cell stack could have been 
installed on any Model 747-400, 777-200, or 777-300 series airplane 
equipped with a Hamilton Sundstrand humidifier having P/N 821486-1 or 
P/N 816086-1, we have added an inspection of Model 747-400, 777-200, 
and 777-300 series airplanes equipped with Hamilton Sundstrand flight 
deck humidifiers to determine if P/N 821486-1 or P/N 816086-1 is 
installed, and as applicable, an inspection to determine if the cell 
stack has P/N 821482-1 or P/N 822976-2. We have added inspections or 
records reviews to paragraphs (a) and (d) of the supplemental NPRM and 
revised the other paragraphs accordingly.
    The applicability of the supplemental NPRM has also been revised to 
``Model 747-400, 777-200, 777-300 series airplanes, equipped with 
Hamilton Sundstrand flight deck humidifiers.'' In addition, the cost 
table has been revised to include the cost of the additional 
inspections and we have revised the number of affected airplanes to 114 
worldwide and 29 of U.S. registry.

Request To Revise Number of Affected Airplanes of U.S. Registry

    One commenter, the airplane manufacturer, requests that the number 
of airplanes of U.S. registry be revised from 12 to none. The commenter 
notes that the original NPRM specifies there are ``35 airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 12 
airplanes of U.S. registry would be affected by this AD.'' The 
commenter states that it has delivered 103 airplanes in production that 
could be fitted with the cell stack with excessive pressure drop 
(although only 23 may have been delivered in that configuration). The 
commenter notes that only one domestic operator has airplanes equipped 
with Hamilton Sundstrand humidifiers and that this operator cannot have 
any Model 777 series airplanes having cell stacks with excessive 
pressure drop. The commenter states the first Model 777 series airplane 
equipped with a Hamilton Sundstrand humidifier for this operator was 
the airplane on which the pressure drop discrepancy was discovered, and 
it was outfitted with a humidifier with an acceptable pressure drop. 
The commenter goes on to state that this operator's flight deck 
humidifier stock is known, and it can be shown that no affected cell 
stacks exist within that operator's fleet. Consequently, the commenter 
believes no airplanes of U.S. registry would be affected by this 
proposed AD.
    We do not agree with the commenter's request to revise the number 
of airplanes of U.S. registry from 12 to none. As stated in the 
previous paragraph ``Request to Withdraw the Proposed AD,'' there is a 
possibility that a defective cell stack could have been installed on 
any Model 747-400, 777-200, or 777-300 series airplane equipped with a 
Hamilton Sundstrand humidifier having P/N 821486-1 or P/N 816086-1. 
Because we have not received confirmation that all Model 747-400, 777-
200, 777-300 series airplanes equipped with Hamilton Sundstrand flight 
deck humidifiers have been screened for the suspect cell stacks, the 
applicability of the supplemental NPRM has been revised and the number 
of airplanes of U.S. registry has been revised to 29.

Request To Remove ``Replacement of the Blanking Plate With a Supplier 
Tested Cell Stack'' Text From Summary and Cost Table

    One commenter, the airplane manufacturer, requests that in the 
Summary of the original NPRM, the text ``or replacement of the blanking 
plate with a supplier tested cell stack'' be removed and the final row 
of the cost table in the Cost Impact section be removed. The commenter 
notes that to mitigate the risk of reduced flight deck airflow the 
original NPRM requires ``For other airplanes, replacement of the cell 
stack with a blanking plate or a new cell stack, or replacement of the 
blanking plate with a supplier-tested cell stack.'' The commenter 
states that a risk of reduced airflow to the flight deck does not exist 
when a blanking plate is installed.
    We agree that if a blanking plate is installed, reduced airflow to 
the flight deck will not occur. However, the text ``or replacement of 
the blanking plate with a supplier-tested cell stack'' is intended to 
prevent a discrepant part from being installed on an airplane on which 
an installed blanking plate is removed and a cell stack is installed. 
Therefore, in the summary of the supplemental NPRM, for the reasons we 
are revising the proposed AD, we have added the text ``requiring 
replacement of the blanking plate with a supplier-tested cell stack if 
necessary'' in order to clarify the intent of the proposed AD. We have 
not changed the cost table.

Request To Clarify Referenced Requirements

    The same commenter states that it is unclear which four 
requirements of paragraph (a)(1) of the original NPRM are being 
referenced in paragraph (a)(2) of the original NPRM that states 
``Replacement of the cell stack with a supplier-tested cell stack in 
accordance with the 4 requirements of paragraph (a)(1) of this AD * * 
*''
    We agree that paragraph (b)(2) (specified as paragraph (a)(2) of 
the original NPRM) should be clarified. The ``4'' in the ``Replacement 
of the cell stack * * *'' sentence was a typographical error. The 
sentence also should have specified that it was a replacement of the 
``end plate'' and not the ``cell stack.'' The intent of the sentence 
was to indicate that the humidifier could be reactivated if the end 
plate was replaced with a supplier-

[[Page 1213]]

tested cell stack. In addition, the sentence references Part 1 of 
Boeing Alert Service Bulletin 747-21A2414, Revision 1, dated October 
26, 2000, as the relevant source of service information for the 
replacement. However, Part 1 of the service bulletin does not include 
procedures for the replacement of the end plate. The replacement of the 
end plate must be done in a method approved by the FAA. We have revised 
paragraphs (b) and (b)(2) of the supplemental NPRM and added paragraph 
(b)(3) of the supplemental NPRM to clarify that there is an option to 
replace the end plate with a supplier-tested cell stack.

Request To Remove Paragraph (c)(3) of the Original NPRM

    The same commenter also requests removing paragraph (c)(3) of the 
original NPRM. The commenter states that paragraph (c)(3) concerns 
replacing a blanking plate with a cell stack. However, the commenter 
believes this is not necessary, as a humidifier with a blanking plate 
does not restrict flight deck airflow. The commenter states that this 
action is not necessary since the risk of reduced airflow to the flight 
deck does not exist when a blanking plate is installed.
    We agree with the commenter that reduced airflow to the flight deck 
does not exist when a blanking plate is installed. However, the purpose 
of paragraph (e)(3) (specified as paragraph (c)(3) of the original 
NPRM) of the supplemental NPRM is to prevent a discrepant part from 
being installed on an airplane if the operator chooses to remove a 
blanking plate and install a cell stack in its place. Thus, while we do 
not agree to remove paragraph (e)(3) (specified as paragraph (c)(3) of 
the original NPRM) of the supplemental NPRM, we have revised the 
wording in paragraph (e)(3) of the supplemental NPRM to, ``If a 
blanking plate is removed, and a cell stack installed, the cell stack 
installation must be done in accordance with Part 3 of the service 
bulletin.''

Request to Revise ``Dehumidifier'' to ``Humidifier''

    The same commenter requests the word ``dehumidifier'' be revised to 
``humidifier.'' The commenter notes that paragraph (e) of the original 
NPRM specifies ``flight deck dehumidifier cell stack.'' The subject of 
the original NPRM is a humidifier cell stack.
    We agree with the commenter. Paragraph (g) (specified as paragraph 
(e) of the original NPRM) of the supplemental NPRM has been revised to 
specify ``flight deck humidifier cell stack.''

Request To Revise Reason Given for Sagging Cell Problem

    The same commenter requests that the cause of the sagging cell 
problem be changed to ``insufficient rigidity in the cell frame.'' The 
commenter notes that the ``Discussion'' section of the original NPRM 
states, ``The sagging has been attributed to difficulties encountered 
during the membrane welding process.'' The commenter states that the 
sagging is actually a result of the cell frame material not being 
rigid. The action taken to correct the sagging cell problem is to 
change the cell frame material in order to make it more rigid.
    We agree with the commenter that the sagging is actually a result 
of the cell frame material not being rigid. However, since the wording 
from the original NPRM ``the sagging has been attributed to 
difficulties encountered during the membrane welding process'' is not 
restated in the supplemental NPRM, no change is made.

Request To Clarify Reason for Increased Pressure

    The same commenter requests that we clarify when there is an 
increased pressure drop across the humidifier. The commenter notes that 
the Discussion section of the original NPRM states ``The result of the 
sagging membrane is an increased pressure drop across the humidifier 
(if it is activated).'' The commenter states that the increased 
pressure drop would exist regardless of whether the humidifier is 
activated or not.
    We agree that the increased pressure drop would exist regardless of 
whether the humidifier is activated or not. Boeing Alert Service 
Bulletins 747-21A2412 and 777-21A0048 do not state that the pressure 
drop occurs only when the humidifier is activated. However, since the 
Discussion section of the original NPRM is not restated in the 
supplemental NPRM, no change is made.

Conclusion

    Since these changes expand the scope of the originally proposed 
rule, we have determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

Changes to Delegation Authority

    Boeing has received a Delegation Option Authorization (DOA). We 
have revised this supplemental NPRM to delegate the authority to 
approve an alternative method of compliance for any repair required by 
this AD to the Authorized Representative for the Boeing DOA 
Organization rather than the Designated Engineering Representative 
(DER).

Cost Impact

    There are approximately 114 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 29 airplanes of U.S. registry 
would be affected by this proposed AD. The following cost estimates 
would vary depending on the actions chosen by the operator.

----------------------------------------------------------------------------------------------------------------
                                                                         Work      Hourly     Parts     Cost per
          Model/series                          Action                  hours       rate       cost     airplane
----------------------------------------------------------------------------------------------------------------
747-400                          Inspect flight deck humidifier for           1        $65         $0        $65
777-200                           part number and inspect flight
777-300                           deck humidifier cell stack for
                                  part number.
747-400                          Replace cell stack with supplier-            5         65      5,100      5,425
                                  tested cell stack.
747-400                          Replace cell stack with end plate            6         65          0        390
                                  and deactivate humidifier.
777-200                          Replace cell stack with blanking             5         65          0        325
777-300                           plate.
777-200                          Replace cell stack with supplier-            5         65      6,053      6,378
777-300                           tested cell stack.
777-200                          Replace blanking plate with                  3         65      6,053      6,248
777-300                           supplier-tested cell stack.
----------------------------------------------------------------------------------------------------------------

    The cost impact figures discussed above are 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

[[Page 1214]]

this proposed 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.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

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 2000-NM-360-AD.

    Applicability: Model 747-400, 777-200, and 777-300 series 
airplanes, equipped with a Hamilton Sundstrand flight deck 
humidifier; certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an increased pressure drop across the humidifier and 
consequent reduced airflow to the flight deck, which could result in 
the inability to clear any smoke that might appear in the flight 
deck, accomplish the following:

Inspections/Records Review: Model 747-400 Series Airplanes

    (a) For Model 747-400 series airplanes: Within 90 days after the 
effective date of this AD, inspect the flight deck humidifier to 
determine whether part number (P/N) 821486-1 is installed. Instead 
of inspecting the flight deck humidifier, a review of airplane 
maintenance records is acceptable if the P/N of the flight deck 
humidifier can be positively determined from that review.
    (1) If a P/N other than P/N 821486-1 is installed, no further 
action is required by this paragraph.
    (2) If P/N 821486-1 is installed, before further flight, inspect 
the flight deck humidifier cell stack to determine whether P/N 
821482-1 is installed and ``DEV 13433'' is not marked next to the 
cell stack part number. Instead of inspecting the flight deck 
humidifier cell stack, a review of airplane maintenance records is 
acceptable if the P/N, including whether ``DEV 13433'' is marked 
next to the P/N, of the flight deck humidifier cell stack can be 
positively determined from that review. If ``DEV 13433'' is marked 
next to P/N 821482-1, no further action is required by this 
paragraph.

Cell Stack Replacement: Model 747-400 Series Airplanes

    (b) If during the inspection required by paragraph (a)(2) of 
this AD, it is determined that the flight deck humidifier cell stack 
has P/N 821482-1 and does not have ``DEV 13433'' marked next to the 
cell stack part number: Before further flight, do the actions 
specified in paragraph (b)(1), (b)(2), or (b)(3) of this AD.
    (1) Replace the cell stack of the flight deck humidifier with a 
supplier-tested cell stack, in accordance with Part 1 of Boeing 
Alert Service Bulletin 747-21A2414, Revision 1, dated October 26, 
2000.
    (2) Replace the cell stack with an end plate and before further 
flight deactivate the flight deck humidifier, in accordance with 
Part 2 of Boeing Alert Service Bulletin 747-21A2414, Revision 1, 
dated October 26, 2000.
    (3) If an end plate is removed, and a supplier-tested cell stack 
installed, the replacement must be done in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA; or according to data meeting the certification basis of 
the airplane approved by an Authorized Representative for the Boeing 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a 
replacement method to be approved, the approval must specifically 
reference this AD. Replacement of the end plate with a supplier-
tested cell stack terminates the requirement to deactivate the 
flight deck humidifier specified in paragraph (b)(2) of this AD.

    Note 1: Boeing Alert Service Bulletin 747-21A2414, Revision 1, 
dated October 26, 2000, refers to Boeing Service Bulletin 747-21-
2405, Revision 4, dated July 29, 1999, as an additional source of 
service information for deactivating the humidifier.


    Note 2: Boeing Alert Service Bulletin 747-21A2414, Revision 1, 
dated October 26, 2000, refers to Hamilton Sundstrand Service 
Bulletins 821486-21-01, dated March 15, 2000, as an additional 
source of service information for the cell stack replacement.

    (c) Replacement of the cell stack before the effective date of 
this AD in accordance with Boeing Alert Service Bulletin 747-
21A2414, dated April 13, 2000, is acceptable for compliance with the 
applicable requirements of paragraphs (b)(1) and (b)(2) of this AD.

Inspections/Records Review: Model 777-200 and -300 Series Airplanes

    (d) For Model 777-200 and 777-300 series airplanes: Within 90 
days after the effective date of this AD, inspect the flight deck 
humidifier to determine if it is P/N 816086-1. Instead of inspecting 
the flight deck humidifier, a review of airplane maintenance records 
is acceptable if the part number P/N of the flight deck humidifier 
can be positively determined from that review.
    (1) If a P/N other than P/N 816086-1 is installed, no further 
action is required by this paragraph.
    (2) If P/N 816086-1 is installed, before further flight, inspect 
the flight deck humidifier cell stack to determine whether P/N 
822976-2 is installed and ``DEV 13433'' is not marked next to the 
cell stack part number. Instead of inspecting the flight deck 
humidifier cell stack, a review of airplane maintenance records is 
acceptable if the P/N, including whether ``DEV 13433'' is marked 
next to the P/N, of the flight deck humidifier cell stack can be 
positively determined from that review. If ``DEV 13433'' is marked 
next to P/N 822976-2, no further action is required by this 
paragraph.

[[Page 1215]]

Cell Stack Replacement: Model 777-200 and -300 Series Airplanes

    (e) If during the inspection required by paragraph (d)(2) of 
this AD, it is determined that the flight deck humidifier cell stack 
has P/N 822976-2 and does not have ``DEV 13433'' marked next to the 
cell stack part number: Before further flight, do the actions 
specified in paragraph (e)(1), (e)(2), or (e)(3) of this AD, in 
accordance with Boeing Service Bulletin 777-21A0048, Revision 1, 
dated September 7, 2000.
    (1) Replace the cell stack with a blanking plate, in accordance 
with Part 1 of the service bulletin; and deactivate the humidifier 
system before further flight in accordance with a method approved by 
the Manager, Seattle ACO, FAA; or according to data meeting the 
certification basis of the airplane approved by an Authorized 
Representative for the Boeing Delegation Option Authorization 
Organization who has been authorized by the Manager, Seattle ACO, to 
make those findings. For a deactivation method to be approved, the 
approval must specifically reference this AD.
    (2) Replace the cell stack with a supplier-tested cell stack, in 
accordance with Part 2 of the service bulletin.
    (3) If a blanking plate is removed, and a cell stack installed, 
the cell stack installation must be done in accordance with Part 3 
of the service bulletin.

    Note 3: Boeing Service Bulletin 777-21A0048, Revision 1, dated 
September 7, 2000, refers to Hamilton Sundstrand Service Bulletin 
816086-21-01, dated March 15, 2000, as an additional source of 
service information for the cell stack replacement.

Parts Installation

    (f) On Model 747-400 series airplanes: As of the effective date 
of this AD, no person may install a flight deck humidifier cell 
stack having P/N 821482-1, unless ``DEV 13433'' is also marked next 
to the cell stack part number.
    (g) On Model 777-200 and 777-300 series airplanes: As of the 
effective date of this AD, no person may install a flight deck 
humidifier cell stack having P/N 822976-2, unless ``DEV 13433'' is 
also marked next to the cell stack part number.

Alternative Methods of Compliance

    (h) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, 
FAA, is authorized to approve alternative methods of compliance for 
this AD.

    Issued in Renton, Washington, on December 29, 2004.
Kevin M. Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-286 Filed 1-5-05; 8:45 am]
BILLING CODE 4910-13-P