# AD 2000-01-02: Turbine Air Discharge Duct in the Air Conditioning System - Type: Airworthiness directive - Status: Current - Products: Textron BAe.125 Series 1000A, BAe.125 Series 1000B and Hawker 1000 - Effective: February 15, 2000 - Published: January 11, 2000, 65 FR 1538–1540 - Issued: January 3, 2000 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-11499 - Docket: 99-NM-80-AD - Registered aircraft: 31 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/47/8f/478f2fc9a6bfebcab522796bcd57bf00de213527aed7785a0d72f52e1d7b3f9e (from https://www.govinfo.gov/content/pkg/FR-2000-01-11/pdf/00-375.pdf) - Federal Register: https://www.federalregister.gov/documents/2000/01/11/00-375/airworthiness-directives-raytheon-model-bae125-series-1000a-and-1000b-airplanes-and-model-hawker - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F16E95035D1F942686256A090075F6ED.0001 - DRS record last changed: January 21, 2026 - Page: https://openairdocs.org/ad/2000-01-02 ## Summary This amendment adopts a new airworthiness directive (AD), applicable to all Raytheon Model BAe.125 series 1000A and 1000B airplanes and Model Hawker 1000 series airplanes, that requires 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 amendment 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 this AD are intended to prevent such disconnection from the CAU or water separator, which could result in cabin depressurization. ## The airworthiness directive 2000-01-02 RAYTHEON AIRCRAFT COMPANY (Formerly Beech): Amendment 39-11499. 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 detectobvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-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, whomay 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. Incorporation by Reference (f) The actions shall be done in accordance with Raytheon Service Bulletin SB 21-3108, dated November 1998. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Raytheon Aircraft Company, Manager Service Engineering, Hawker Customer Support Department, P.O. Box 85, Wichita, Kansas 67201-0085. Copies may be inspected 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; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (g) This amendment becomes effective on February 15, 2000. ## Rule preamble ### Supplementary information A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all Raytheon Model BAe.125 series 1000A and 1000B airplanes and Model Hawker 1000 series airplanes was published in the Federal Register on October 14, 1999 (64 FR 55638). That action proposed to 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. Comments Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public. Conclusion The FAA has determined that air safety and the public interest require the adoption of the rule as proposed. 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 will be affected by this AD, that it will take approximately 9 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the 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 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 adopted herein will 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 final rule does not have federalism implications under Executive Order 13132. For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A3EU](https://openairdocs.org/tcds/A3EU): Textron Aviation Inc.; names 3 of 50 models: BAe.125 Series 1000A, BAe.125 Series 1000B, Hawker 1000 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 31 (31 by airframe model, 0 by engine model) - Makers: Raytheon Corporate Jets 12, British Aerospace 9, Corporate Jets 9, Raytheon 1 Models with the most aircraft: - [British Aerospace BAE 125 SERIES 1000A](https://openairdocs.org/model/british-aerospace-bae-125-series-1000a): 9 aircraft (airframe model) - [Corporate Jets BAE 125-1000A](https://openairdocs.org/model/corporate-jets-bae-125-1000a): 9 aircraft (airframe model) - [Raytheon Corporate Jets HAWKER 1000](https://openairdocs.org/model/raytheon-corporate-jets-hawker-1000): 8 aircraft (airframe model) - [Raytheon Corporate Jets BAE 125-1000A](https://openairdocs.org/model/raytheon-corporate-jets-bae-125-1000a): 4 aircraft (airframe model) - [Raytheon HAWKER 1000](https://openairdocs.org/model/raytheon-hawker-1000): 1 aircraft (airframe model) All 6 models: https://openairdocs.org/ad/2000-01-02/models.md Every aircraft: https://openairdocs.org/ad/2000-01-02/aircraft.md ## Related documents - [Proposed rule 99-NM-80-AD](https://openairdocs.org/proposed/99-NM-80-AD): Notice of proposed rulemaking (NPRM), published Oct 14, 1999 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.