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 notice must submit a selfaddressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 2000NM212AD.'' 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. 2000NM212AD, 1601 Lind Avenue, SW., Renton, Washington 980554056.

Discussion

The FAA has received reports indicating that in four instances the turbine air discharge duct became disconnected from the cold air unit and/or from the water separator in flight, resulting in cabin depressurization. The disconnection apparently occurred, because the design of the sleeve connection, with bedding tape installed under the clamps, is prone to slippage. This condition, if not corrected, may lead to the loss of air supply to maintain adequate cabin pressure. Such a loss of cabin pressure at high altitude would require emergency procedures, such as use of oxygen, auxiliary pressurization, or emergency descent.

If cabin depressurization occurs on long overwater flights, descending to a lower altitude may not allow sufficient range to reach a suitable airfield. Descending to a lower altitude would result in higher fuel consumption and, therefore, less range. If the fuel consumption and reserves had been calculated based on a fuel burn rate at a high cruise altitude, and a loss of pressure forced the crew to alter their plan, then the available fuel may no longer allow them to reach their destination or to reach it with sufficient reserves. Explanation of Relevant Service Information

The FAA has reviewed and approved Raytheon Service Bulletin SB 21 3377, Revision 1, dated July 2000, which describes procedures for removing the clamps, bedding strips, and rubber connecting sleeves on both ends of the turbine air discharge duct and the water separator and replacing the clamps and connecting sleeves with new, improved components. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously.
[[Page 49524]]

Cost Impact

There are approximately 220 airplanes of the affected design in the worldwide fleet. The FAA estimates that 154 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 installation, and that the average labor rate is $60 per work hour. Required parts would cost approximately $492 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $149,688, or $972 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 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.

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:

Raytheon Aircraft Company: Docket 2000NM212AD.

Applicability: Model BAe.125 Series 800A (C29A and U125) series airplanes, Hawker 800 (U125A) series airplanes up to and including serial number 258406, and Hawker 800XP series airplanes up to and including serial number 258459; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent the turbine air discharge duct or water separator outlet duct from disconnecting from the cold air unit turbine or from the water separator, resulting in the loss of air supply to maintain adequate cabin pressure, accomplish the following: Replacement
(a) Remove the clamps, bedding tapes, and rubber connecting sleeves at the ends of the air turbine discharge duct and the water separator, and replace the clamps and rubber connecting sleeves with new, improved components, in accordance with the Accomplishment Instructions of Raytheon Service Bulletin SB 213377, Revision 1, dated July 2000, at the earliest of the times specified in paragraphs (a)(1), (a)(2), and (a)(3) of this AD.
(1) Prior to any extended overwater operation.
(2) Within the next 300 hours timeinservice after the
effective date of this AD.
(3) Within the next six months after the effective date of this AD.

Note 2: An extended overwater operation is defined in 14 CFR 1.1 as ``* * * an operation over water at a horizontal distance of more than 50 nautical miles from the nearest shoreline. * * *'' Alternative Methods of Compliance
(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA, Small Airplane Directorate.

Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.
Special Flight Permits
(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on August 8, 2000. Donald L. Riggin,
Acting Manager, Transport Airplane Directorate Aircraft Certification Service.
[FR Doc. 0020507 Filed 81100; 8:45 am] BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Paul C. DeVore, Aerospace Engineer, Systems and Propulsion Branch, ACE116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, MidContinent Airport, Wichita, Kansas 67209; telephone (316) 9464142; fax (316) 9464407.