AD 77-21-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus Helicopters Deutschland GmbH | BO-105A | Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | BO-105C | Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters |
Unsafe Condition
The unsafe condition involves improper socket connections (1 VED and 1 VEE) and plugs (110 VVa and 210 VVa) in the main relay box, which could lead to electrical system failure or fire due to arcing or short circuits.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove socket connections 1 VED and 1 VEE from the main relay box, remove plugs 110 VVa and 210 VVa along with their associated receptacles and wiring bundles, and install the generator wiring assembly per MBB Service Bulletin No. 90-11 dated April 17, 1975, or an FAA-approved equivalent.
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Compliance Time
within the next 600 hours time in service after the effective date of this AD
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Affected Aircraft
Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C helicopters, Serial Number V4 through V10, and S1 through S160
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Federal Register Abstract
Wiring
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_77-21-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-21-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters Subject: Wiring Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/14/1977 Make: Airbus Helicopters Deutschland GmbH Model: BO-105A | BO-105C Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 77-21-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3061 AD NUMBER: 77-21-07 SUBJECT HEADING: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters ACTION: SUMMARY: DATES: Effective November 14, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-21-07 MESSERSCHMITT-BOLKOW-BLOHM (MBB): Amendment 39-3061. Applies to Model BO-105A and BO-105C helicopters, Serial Number V4 through V10, and S1 through S160, certificated in all categories. Compliance required within the next 600 hours time in service after the effective date of this AD, unless already accomplished. Remove socket connections 1 VED and 1 VEE from main relay box, remove plugs 110 VVa and 210 VVa together with associated receptacles and wiring bundles, and install generator wiring assembly, in accordance with subparagraph 2B of MBB Service Bulletin No. 90-11 dated April 17, 1975, or an FAA-approved equivalent. This amendment becomes effective November 14, 1977. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_77-21-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 77-21-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters Subject: Wiring Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/14/1977 Make: Airbus Helicopters Deutschland GmbH Model: BO-105A | BO-105C Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 77-21-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3061 AD NUMBER: 77-21-07 SUBJECT HEADING: Airworthiness Directives; Messerschmitt-Bolkow-Blohm (MBB) Model BO-105A and BO-105C Helicopters ACTION: SUMMARY: DATES: Effective November 14, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 77-21-07 MESSERSCHMITT-BOLKOW-BLOHM (MBB): Amendment 39-3061. Applies to Model BO-105A and BO-105C helicopters, Serial Number V4 through V10, and S1 through S160, certificated in all categories. Compliance required within the next 600 hours time in service after the effective date of this AD, unless already accomplished. Remove socket connections 1 VED and 1 VEE from main relay box, remove plugs 110 VVa and 210 VVa together with associated receptacles and wiring bundles, and install generator wiring assembly, in accordance with subparagraph 2B of MBB Service Bulletin No. 90-11 dated April 17, 1975, or an FAA-approved equivalent. This amendment becomes effective November 14, 1977. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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