# Airworthiness Directives; Raytheon Model BAe.125 Series 1000A and 1000B Airplanes and Model Hawker 1000 Series Airplanes > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A99-26869 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** October 14, 1999 - **Citation:** 64 FR 55638 ## Text DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 99-NM-80-AD] RIN 2120-AA64 Airworthiness Directives; Raytheon Model BAe.125 Series 1000A and 1000B Airplanes and Model Hawker 1000 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 all Raytheon Model BAe.125 series 1000A and 1000B airplanes and Model Hawker 1000 series airplanes. This proposal would require an inspection to determine the integrity of the duct connection on both ends of the turbine air discharge duct in the air conditioning system, an inspection to measure the bead height on the ends of the turbine air discharge duct; and corrective actions, if necessary. This proposal is prompted by reports indicating that the turbine air discharge duct disconnected from the cold air unit (CAU) or water separator due to insufficient bead height on the ends of the turbine air discharge duct. The actions specified by the proposed AD are intended to prevent such disconnection from the CAU or water separator, which could result in cabin depressurization. DATES: Comments must be received by November 29, 1999. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-80-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Raytheon Aircraft Company, Manager Service Engineering, Hawker Customer Support Department, P.O. Box 85, Wichita, Kansas 67201- 0085. 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-ContinentAirport, 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. [[Page 55639]] 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 99-NM-80-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. 99-NM-80-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The FAA has received several reports indicating that the turbine air discharge duct disconnected from the cold air unit (CAU) or water separator in flight on Raytheon Model BAe.125 series 1000A and 1000B airplanes and Model Hawker 1000 series airplanes during flight. Investigation revealed that the bead height on the ends of the turbine air discharge duct was smaller than the design requirement, which could allow the rubber connecting sleeves to disconnect. Disconnection of the turbine air discharge duct from the CAU or water separator could result in loss of normal air supply to maintain cabin pressurization. Explanation of Relevant Service Information The FAA has reviewed and approved Raytheon Aircraft Service Bulletin SB 21-3108, dated November 1998, which describes procedures for a one-time visual inspection to determine the integrity of the duct connection on both ends of the turbine air discharge duct in the air conditioning system; a one-time detailed inspection to measure the bead height on the ends of the turbine air discharge duct; and corrective actions, if necessary. The corrective actions involve adjustment of the clamps, and either rework of the duct or replacement of the duct with a new duct. 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 52 airplanes of the affected design in the worldwide fleet. The FAA estimates that 35 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 9 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $18,900, or $540 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. Regulatory Impact The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 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: Raytheon Aircraft Company (Formerly Beech): Docket 99-NM-80-AD. Applicability: All Model BAe.125 series 1000A and 1000B airplanes and Model Hawker 1000 series airplanes, 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 (d) 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 in the air conditioning system from disconnecting from the CAU or water separator in flight, which could result in cabin depressurization, accomplish the following: Inspections (a) Within 25 flight hours after the effective date of this AD, perform a general visual inspection to determine the integrity of the duct connections (i.e., ensure that the duct and securing clamps are in place, the sleeve is central to the joint gap, and the clamps are clear of the duct bead) on both ends of the turbine air discharge duct in accordance with Raytheon Service Bulletin SB 21- 3108, dated November 1998. If any discrepancy is detected, prior to further flight, adjust the clamps in accordance with the service bulletin. Note 2: For the purposes of this AD, a general visual inspection is defined as: ``A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop- [[Page 55640]] light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.'' (b) Within 300 flight hours or 6 months after the effective date of this AD, whichever occurs first, perform a one-time detailed inspection to measure the bead height on the ends of the turbine air discharge duct in accordance with Raytheon Service Bulletin SB 21- 3108, dated November 1998. If the bead height does not conform to the dimension shown in the service bulletin, prior to further flight, either rework the duct or replace the duct with a new duct, in accordance with the service bulletin. Note 3: For the purposes of this AD, a detailed inspection is defined as: ``An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.'' Spares (c) As of the effective date of this AD, no person shall install a turbine air discharge duct, part number 25-9VF425-1A, on any airplane, unless that duct has been inspected in accordance with Part II of Raytheon Service Bulletin SB 21-3108, dated November 1998. Alternative Methods of Compliance (d) 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 4: 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 (e) 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 October 7, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-26869 Filed 10-13-99; 8:45 am] BILLING CODE 4910-13-P --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A99-26869. Public record. Not legal advice.