AD 75-17-21
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Textron Aviation Inc. | BH.125 Series 400A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | BH.125 Series 600A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A/R-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A/S-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A/R | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A/RA | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 400A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes |
Unsafe Condition
Rapid loss of cabin pressurization due to displacement of Hellerman type cabin pressure seal bungs.
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Required Actions
Inspect all Hellerman type cabin pressure seal bungs for displacement within 50 hours time in service after the effective date. Rework as necessary per Maintenance Manual instructions and conduct a cabin leak rate check after reinstallation.
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Compliance Time
within 50 hours time in service after the effective date of this AD
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Affected Aircraft
HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 airplanes certificated in all categories.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Cabin Pressurization
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_75-17-21.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 75-17-21 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes Subject: Cabin Pressurization Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/19/1975 Make: Textron Aviation Inc. Model: BH.125 Series 400A | BH.125 Series 600A | DH.125 Series 1A | DH.125 Series 1A-522 | DH.125 Series 1A...Show more Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 75-17-21 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2323 AD NUMBER: 75-17-21 SUBJECT HEADING: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes ACTION: SUMMARY: DATES: Effective August 19, 1975. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 75-17-21 HAWKER SIDDELEY AVIATION, LTD: Amendment 39-2323. Applies to DH-125 and BH-125 airplanes certificated in all categories. Compliance required as indicated. To prevent possible rapid loss of cabin pressurization, accomplish the following: Within 50 hours time in service after the effective date of this AD, unless already accomplished, inspect all Hellerman type cabin pressure seal bungs for displacement and rework as necessary in accordance with the following: (a) Locate all Hellerman type cabin pressure seal bungs for the particular aircraft being inspected. NOTE: Refer to the relevant aircraft wiring diagram manual (2 volumes) and to the maintenance practices in the Maintenance Manual, Chapter 24-00 (all series pre-600) and Chapter 24-01 (series 600). Pressure bung installations may be of the normal or reverse type assembly as defined in the Maintenance Manual reference noted in paragraph (c) of this AD. The total number may vary from one airplane to another depending on the electrical equipment installed. (b) Gain access to the bungs in accordance with the procedures in the Maintenance Manual, Chapters 24 and 25. (c) Inspect the bungs (both normal and reverse assemblies) for displacement and reinspect and/or rework as necessary in accordance with the instructions contained in Part B of temporary revision dated April 1, 1975, to HSA Maintenance Manual, Chapter 24-00 (all series except 600) and Chapter 24-01 (series 600), or the appropriate sections of the referenced chapters if the temporary revision has been incorporated into the HSA Maintenance Manual, or an FAA-approved equivalent. (d) Where pressure bung(s) have been removed for rework, upon re-installation of the pressure bung(s) conduct a cabin leak rate check in accordance with the appropriate provisions of chapter 21 of the HSA Maintenance Manual prior to further flight to ensure the integrity of the pressure cabin. This amendment becomes effective August 19, 1975. FOOTER:
Document Text
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AD Final Rules - DRS_75-17-21.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 75-17-21 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes Subject: Cabin Pressurization Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/19/1975 Make: Textron Aviation Inc. Model: BH.125 Series 400A | BH.125 Series 600A | DH.125 Series 1A | DH.125 Series 1A-522 | DH.125 Series 1A...Show more Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 75-17-21 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2323 AD NUMBER: 75-17-21 SUBJECT HEADING: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Models DH-125 and BH-125 Airplanes ACTION: SUMMARY: DATES: Effective August 19, 1975. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 75-17-21 HAWKER SIDDELEY AVIATION, LTD: Amendment 39-2323. Applies to DH-125 and BH-125 airplanes certificated in all categories. Compliance required as indicated. To prevent possible rapid loss of cabin pressurization, accomplish the following: Within 50 hours time in service after the effective date of this AD, unless already accomplished, inspect all Hellerman type cabin pressure seal bungs for displacement and rework as necessary in accordance with the following: (a) Locate all Hellerman type cabin pressure seal bungs for the particular aircraft being inspected. NOTE: Refer to the relevant aircraft wiring diagram manual (2 volumes) and to the maintenance practices in the Maintenance Manual, Chapter 24-00 (all series pre-600) and Chapter 24-01 (series 600). Pressure bung installations may be of the normal or reverse type assembly as defined in the Maintenance Manual reference noted in paragraph (c) of this AD. The total number may vary from one airplane to another depending on the electrical equipment installed. (b) Gain access to the bungs in accordance with the procedures in the Maintenance Manual, Chapters 24 and 25. (c) Inspect the bungs (both normal and reverse assemblies) for displacement and reinspect and/or rework as necessary in accordance with the instructions contained in Part B of temporary revision dated April 1, 1975, to HSA Maintenance Manual, Chapter 24-00 (all series except 600) and Chapter 24-01 (series 600), or the appropriate sections of the referenced chapters if the temporary revision has been incorporated into the HSA Maintenance Manual, or an FAA-approved equivalent. (d) Where pressure bung(s) have been removed for rework, upon re-installation of the pressure bung(s) conduct a cabin leak rate check in accordance with the appropriate provisions of chapter 21 of the HSA Maintenance Manual prior to further flight to ensure the integrity of the pressure cabin. This amendment becomes effective August 19, 1975. FOOTER:
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Retrieved: Apr 8, 2026
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