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 FAApublic 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 selfaddressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 2000NM360AD.'' 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, ANM114, Attention: Rules Docket No. 2000NM360AD, 1601 Lind Avenue, SW., Renton, Washington 980554056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to Boeing Model 747400, 777200, and 777300 series airplanes, equipped with a Hamilton Sundstrand flight deck humidifier, was published as a supplemental notice of proposed rulemaking (referred to hereafter as the first SNPRM) in the Federal Register on January 6, 2005 (70 FR 1211).

The first SNPRM would have required an inspection of the flight deck humidifier to determine certain part numbers. The first SNPRM also would have required, for certain airplanes, replacing the cell stack of the flight deck humidifier with a suppliertested cell stack, or replacing the cell stack with an end plate and subsequent deactivation of the flight deck humidifier, if necessary. For other airplanes, the first SNPRM would have required replacing the cell stack with a suppliertested cell stack, or replacing the cell stack with a blanking plate and subsequent deactivation of the humidifier system, if necessary. The first SNPRM also would have allowed end plates or blanking plates to be replaced with cell stacks.

The first SNPRM was prompted by reports of sagging cell stack membranes of the flight deck humidifiers. That condition, if not corrected, could result in 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.

Actions Since Issuance of First SNPRM

Since the issuance of the first SNPRM, Boeing has issued Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005 (Revision 1, dated October 26, 2000, was referenced as an applicable source of service information for doing the actions in that SNPRM); and Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005 (Revision 1, dated September 7, 2000, was referenced as an applicable source of service information for doing the actions in the first SNPRM). Revision 2 of the alert service bulletins contains essentially the same procedures for the replacement of certain cell stacks of the flight deck humidifier. However, Revision 2 of the alert service bulletins adds airplanes to the effectivity. For those airplanes, Revision 2 of the alert service bulletin adds a procedure to inspect for a certain flight deck humidifier and inspect for a certain cell stack if necessary. Revision 2 of the alert service bulletins also specifies on which airplanes the replacement should be accomplished.

We have made the following changes to the first SNPRM:

We have also given due consideration to the comments received in response to the first SNPRM.

Request To Revise Number of Affected Airplanes

One commenter, the manufacturer, requests that the number of airplanes that could be fitted with the potentially defective cell stack be revised from 114 airplanes, as stated in the ``Request to Withdraw the Proposed AD'' section of the first SNPRM, to 176 airplanes. The commenter states that 176 humidifiers have been delivered that could have the potentially defective cell stacks.

We agree with the commenter that the total number of airplanes that could be fitted with the potentially defective cell stack is 176. We have revised the number in the Cost Impact section of this second SNPRM.

Request To Allow Additional Records Review

The same commenter requests that we add an additional records review to allow operators to show compliance
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with the intent of the first SNPRM. The commenter states that if an airplane or retrofit kit was delivered after December 16, 1999, and the record review shows that the humidifier or cell stack was not replaced since, no inspection or replacement of the humidifier is needed. The commenter notes that December 16, 1999 is the delivery date of the first airplane that was delivered with an acceptable cell stack that was screened in production. The commenter contends that all humidifier deliveries would thereafter contain a cell stack that is not susceptible to the unsafe condition.

We partially agree with the commenter. We acknowledge that airplanes delivered after December 16, 1999, would not require that the humidifier be inspected or replaced if there has not been any maintenance on the humidifier and the appropriate part markings could be determined. However, we have not revised the requirements for the records review specified in the first SNPRM since this review would include airplanes delivered with a known good cell stack. As specified in paragraphs (c) and (f) of this second SNPRM, a records review would be allowed in lieu of the inspection.

Request To Revise Nomenclature

The same commenter requests that the term ``end plate'' in the first SNPRM be revised to ``blanking plate.'' The commenter states that an end plate is actually a part that exists in the cell stack assembly, while a blanking plate is a part that can be installed in lieu of the cell stack. The commenter recommends that the first SNPRM describe part number (P/N) 10011571 as a blanking plate.

We agree with the commenter. Where the first SNPRM specifies an end plate, we have revised this second SNPRM to specify a blanking plate. Clarification of P/Ns

Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005, specifies the cell stack P/N as 1031112 in paragraph 3. of ``Group 23: Part 3Cell Stack Part Number Inspection'' of the Accomplishment Instructions of the service bulletin. The correct P/N is 10031112.

Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005, specifies the cell stack P/N as 103111 in paragraph 2.C. of ``Parts Necessary For Each Airplane'' and 2.D. of ``Parts Necessary to Change Spares'' of the service bulletin. The correct P/N is 10031111. Explanation of Change Made to This AD

We have revised paragraph (d)(1) of this second SNPRM to clarify the delegation authority for Authorized Representatives for the Boeing Commercial Airplanes Delegation Option Authorization.
Clarification of Alternative Method of Compliance (AMOC) Paragraph

We have revised this second SNPRM to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Conclusion

Since this change expands the scope of this second SNPRM, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Cost Impact

There are approximately 176 airplanes of the affected design in the worldwide fleet. The FAA estimates that 29 airplanes of U.S. registry would be affected by this second SNPRM. The cost per airplane would range between $390 and $6,248 per airplane, depending on the actions chosen by the operator. The fleet cost estimate would not exceed $181,192.
Estimated Costs Cost per Model/series Action Work hours Hourly rate Parts cost airplane 747400, 777200, 777300........... Inspect flight deck 1 $65 $0 $65 humidifier for part
number and inspect
flight deck
humidifier cell stack for part number.
747400............................. Replace cell stack 3 65 5,100 5,295 with new or supplier tested cell stack.
747400............................. Replace cell stack 5 65 0 325 with blanking plate
and deactivate
humidifier.
777200, 777300.................... Replace cell stack 3 65 0 195 with blanking plate. 777200, 777300.................... Replace cell stack 3 65 6,053 6,248 with new or supplier tested cell stack.
777200, 777300.................... Replace blanking plate 1 65 6,053 6,118 with suppliertested

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 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.

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.
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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 39AIRWORTHINESS 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 2000NM360AD.

Applicability: Model 747400, 777200, and 777300 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005; and Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005.

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:
Cell Stack Replacement: Model 747400 Series Airplanes
(a) For Model 747400 series airplanes identified as Group 1 in Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005: Within 90 days after the effective date of this AD, do the replacement specified in paragraph (a)(1) or (a)(2) of this AD. For flight deck humidifiers with a blanking plate: If the blanking plate is removed and a new or suppliertested cell stack is installed, the replacement must be done in accordance with the Accomplishment Instructions of Hamilton Sundstrand Service Bulletins 8214862101, dated March 15, 2000; and after the replacement, the flight deck humidifier may be activated in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747212405, Revision 4, dated July 29, 1999.
(1) Replace the cell stack of the flight deck humidifier with a suppliertested cell stack, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747 21A2414, Revision 2, dated July 7, 2005.
(2) Replace the cell stack of the flight deck humidifier with a blanking plate and, before further flight, deactivate the flight deck humidifier, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005.

Note 1: Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005, refers to Boeing Service Bulletin 747212405, Revision 4, dated July 29, 1999, as an additional source of service information for deactivating the humidifier.

Note 2: Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005, refers to Hamilton Sundstrand Service Bulletins 8214862101, dated March 15, 2000, as an additional source of service information for the cell stack replacements.
(b) 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; or Revision 1, dated October 26, 2000; is acceptable for compliance with the applicable requirements of paragraphs (a)(1) and (a)(2) of this AD.
Inspections/Records Review: Model 747400 Series Airplanes
(c) For Model 747400 series airplanes identified as Groups 2 and 3 in Boeing Alert Service Bulletin 74721A2414, Revision 2, dated July 7, 2005: Within 90 days after the effective date of this AD, inspect the flight deck humidifier to determine whether part number (P/N) 8214861 is installed, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747 21A2414, Revision 2, dated July 7, 2005. 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 8214861 is installed, no further action is required by this paragraph.
(2) If P/N 8214861 is installed, inspect the flight deck humidifier cell stack to determine whether P/N 8214821 is installed and ``DEV 13433'' is not marked next to the cell stack part number, in accordance with Part 3 of the Accomplishment Instructions of the alert service bulletin. 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.
(i) If the cell stack has P/N 8214822 or 10031112, or if ``DEV 13433'' is marked next to P/N 8214821, no further action is required by this paragraph.
(ii) If the cell stack has P/N 8214821 and does not have ``DEV 13433'' marked next to the cell stack part number: Before further flight, do the replacement specified in paragraph (a) of this AD. Cell Stack Replacement: Model 777200 and 300 Series Airplanes (d) For Model 777200 and 777300 series airplanes identified as Groups 1 through 5 in Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005: Within 90 days after the effective date of this AD, do the replacement specified in paragraph (d)(1) or (d)(2) of this AD. For flight deck humidifiers with a blanking plate: If a blanking plate is removed and a new or suppliertested cell stack installed, the cell stack installation must be done in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005; and after the installation, the humidifier system may be activated in accordance with Accomplishment Instructions of Boeing Service Bulletin 777210035, Revision 1, dated October 19, 2000.
(1) Replace the cell stack with a blanking plate, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005; and, before further flight, deactivate the humidifier system in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or in accordance with data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization who has been authorized by the Manager, Seattle ACO, to make those findings. For a deactivation method to be approved, the deactivation must meet the certification basis of the airplane, and the approval must specifically reference this AD.
(2) Replace the cell stack with a suppliertested cell stack, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005.

Note 3: Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005, refers to Hamilton Sundstrand Service Bulletin 8160862101, dated March 15, 2000, as an additional source of service information for the cell stack replacement.
(e) Replacement of the cell stack before the effective date of this AD in accordance with Boeing Service Bulletin 77721A0048, Revision 1, dated September 7, 2000, is
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acceptable for compliance with the applicable requirements of paragraphs (d)(1) and (d)(2) of this AD.
Inspections/Records Review: Model 777200 and 300 Series Airplanes (f) For Model 777200 and 777300 series airplanes identified as Groups 6 and 7 in Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005: Within 90 days after the effective date of this AD, inspect the flight deck humidifier to determine if it is P/N 8160861, in accordance with Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 77721A0048, Revision 2, dated July 14, 2005. 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 8160861 is installed, no further action is required by this paragraph.
(2) If P/N 8160861 is installed, inspect the flight deck humidifier cell stack to determine whether P/N 8229762 is installed and ``DEV 13433'' is not marked next to the cell stack part number, in accordance with Part 4 of the Accomplishment Instruction of the alert service bulletin. 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.
(i) If the cell stack has P/N 8229763 or 10031111, or if ``DEV 13433'' is marked next to P/N 8229762, no further action is required by this paragraph.
(ii) If the cell stack has P/N 8229762 and does not have ``DEV 13433'' marked next to the cell stack part number, before further flight, do the replacement specified in paragraph (d) of this AD. Parts Installation
(g) On Model 747400 series airplanes: As of the effective date of this AD, no person may install a flight deck humidifier cell stack having P/N 8214821, unless ``DEV 13433'' is also marked next to the cell stack part number.
(h) On Model 777200 and 777300 series airplanes: As of the effective date of this AD, no person may install a flight deck humidifier cell stack having P/N 8229762, unless ``DEV 13433'' is also marked next to the cell stack part number.
Alternative Methods of Compliance
(1) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, is authorized to approve alternative methods of compliance for this AD.
(2) Before using any AMOC approved in accordance with 14 CFR 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Issued in Renton, Washington, on December 27, 2005. Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. E58244 Filed 1306; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT

Jeffrey S. Palmer, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM150S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, [[Page 300]]
Washington 980554056; telephone (425) 9176481; fax (425) 9176590.