Airworthiness Directives; Raytheon Model BAe.125, Hawker 800 (U-125A), and Hawker 800XP Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Model BAe.125, Hawker 800 (U-125A), and Hawker 800XP series airplanes. This proposal would require removal of existing clamps, bedding tapes, and rubber connecting sleeves at the ends of the turbine air discharge duct and the water separator, and replacement of the clamps and rubber connecting sleeves with new, improved components. This action is intended 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. Loss of adequate cabin pressure at high altitude would require emergency procedures, such as use of oxygen, auxiliary pressurization, or emergency descent.

DATES:

Comments must be received by September 28, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-212-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. 2000-NM-212-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 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Raytheon Aircraft Company, 9709 East Central, Wichita, Kansas 67206. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

FOR FURTHER INFORMATION CONTACT:

Paul C. DeVore, Aerospace Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4142; fax (316) 946-4407.

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 notice 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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-212-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-212-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

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.

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 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.