AD 77-13-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Textron Aviation Inc. | BH.125 Series 400A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | BH.125 Series 600A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A/R-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 1A/S-522 | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A/R | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 3A/RA | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
| aircraft | Textron Aviation Inc. | DH.125 Series 400A | Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes |
Unsafe Condition
Failure of the knife edges of the emergency brake reducing valve, P/N AC.61516, leading to complete loss of emergency braking capability without advance warning.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the emergency brake control valve knife edges with new parts per Service Bulletin 32-167 Part A or replace the entire emergency brake reducing valve (P/N AC.61516) with a valve fitted with new knife edges per Service Bulletin 32-167 Part B, followed by recurring compliance at intervals not exceeding 4500 landings since last compliance.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Prior to the accumulation of 4500 landings, 200 landings, or as specified based on existing records and landing counts as detailed in the AD.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 airplanes, all series, certificated in all categories.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Emergency Brake Control Valve
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_77-13-11.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-13-11 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes Subject: Emergency Brake Control Valve Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/25/1977 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: 77-13-11 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2936 AD NUMBER: 77-13-11 SUBJECT HEADING: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes ACTION: SUMMARY: DATES: Effective July 25, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-13-11 HAWKER SIDDELEY AVIATION, LTD: Amendment 39-2936. Applies to Model DH/BH-125 airplanes, all series, certificated in all categories. Compliance is required as indicated, unless already accomplished. To prevent possible failure of the knife edges of the emergency brake reducing valve, P/N AC.61516, and consequent complete loss of emergency braking capability without advance warning, accomplish the following: (a) Comply with paragraph (b) or (c) of this AD as follows, and, thereafter, continue to comply with paragraph (b) or (c) of this AD at intervals not to exceed 4500 landings since last compliance. (1) For airplanes having emergency brake control valve knife edges that have accumulated less than 4300 landings, since new, on the effective date of this AD, compliance is required prior to the accumulation of 4500 landings. (2) For airplanes having emergency brake control valve knife edges that have accumulated 4300 or more landings, since new, on the effective date of this AD, compliance is required prior to the accumulation of an additional 200 landings. (3) For airplanes for which no records exist that indicate the number of landings the emergency brake control valve knife edges have accumulated, compliance is required prior to the accumulation of 200 landings after the effective date of this AD. (b) Replace the emergency brake control valve knife edges with new parts in accordance with Part A of Section 2 entitled "Accomplishment Instructions" of Hawker Siddeley Aviation, Ltd., Service Bulletin 32-167, dated January 27, 1976, or an FAA-approved equivalent. (c) Replace the entire emergency brake reducing valve, P/N AC.61516, with a valve fitted with new knife edges and install the valve in accordance with Part B of the section entitled "Accomplishment Instructions" of Hawker Siddeley Aviation, Ltd., Service Bulletin 32-167, dated January 27, 1976, or an FAA-approved equivalent. This amendment becomes effective July 25, 1977. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_77-13-11.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-13-11 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes Subject: Emergency Brake Control Valve Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/25/1977 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: 77-13-11 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-2936 AD NUMBER: 77-13-11 SUBJECT HEADING: Airworthiness Directives; HAWKER SIDDELEY AVIATION, LTD Model DH/BH-125 Airplanes ACTION: SUMMARY: DATES: Effective July 25, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-13-11 HAWKER SIDDELEY AVIATION, LTD: Amendment 39-2936. Applies to Model DH/BH-125 airplanes, all series, certificated in all categories. Compliance is required as indicated, unless already accomplished. To prevent possible failure of the knife edges of the emergency brake reducing valve, P/N AC.61516, and consequent complete loss of emergency braking capability without advance warning, accomplish the following: (a) Comply with paragraph (b) or (c) of this AD as follows, and, thereafter, continue to comply with paragraph (b) or (c) of this AD at intervals not to exceed 4500 landings since last compliance. (1) For airplanes having emergency brake control valve knife edges that have accumulated less than 4300 landings, since new, on the effective date of this AD, compliance is required prior to the accumulation of 4500 landings. (2) For airplanes having emergency brake control valve knife edges that have accumulated 4300 or more landings, since new, on the effective date of this AD, compliance is required prior to the accumulation of an additional 200 landings. (3) For airplanes for which no records exist that indicate the number of landings the emergency brake control valve knife edges have accumulated, compliance is required prior to the accumulation of 200 landings after the effective date of this AD. (b) Replace the emergency brake control valve knife edges with new parts in accordance with Part A of Section 2 entitled "Accomplishment Instructions" of Hawker Siddeley Aviation, Ltd., Service Bulletin 32-167, dated January 27, 1976, or an FAA-approved equivalent. (c) Replace the entire emergency brake reducing valve, P/N AC.61516, with a valve fitted with new knife edges and install the valve in accordance with Part B of the section entitled "Accomplishment Instructions" of Hawker Siddeley Aviation, Ltd., Service Bulletin 32-167, dated January 27, 1976, or an FAA-approved equivalent. This amendment becomes effective July 25, 1977. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.