AD 61-21-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Martin Corporation | 188A | LOCKHEED All Model 188 Aircraft |
| aircraft | Lockheed Martin Corporation | 188C | LOCKHEED All Model 188 Aircraft |
Unsafe Condition
Inadvertent tripping of compass circuit breakers due to bumping the ganging bar by the observer seat occupant, leading to loss of heading information.
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Required Actions
Inspect pilot's and copilot's compass circuit breakers. If ganged, remove ganging bars or install protective guard preventing inadvertent operation of the ganging bar.
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Compliance Time
Within the next 100 hours' time in service after the effective date of this AD
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Affected Aircraft
Lockheed Martin Corporation Model 188A and 188C aircraft
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Federal Register Abstract
Compass Circuit Breakers
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_61-21-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 61-21-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED All Model 188 Aircraft Subject: Compass Circuit Breakers Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/02/1961 Make: Lockheed Martin Corporation Model: 188A | 188C Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 61-21-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 61-21-05 SUBJECT HEADING: LOCKHEED All Model 188 Aircraft ACTION: SUMMARY: DATES: Effective November 2, 1961. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 61-21-05 LOCKHEED: Amdt. 342 Part 507 Federal Register October 3, 1961. Applies to All Model 188 Aircraft. Compliance required as indicated. Several instances of inadvertent tripping of compass circuit breakers have occurred due to bumping the ganging bar by the occupant of the observers seat. Due to the effect of the loss of heading information upon operational safety, accomplishment of the following is required: Within the next 100 hours' time in service after the effective date of this AD, inspect the pilot's and copilot's compass circuit breakers, and if the circuit breakers are ganged together, either remove the ganging bars, or install a protective guard which precludes inadvertent operation of the ganging bar. (These circuit breakers are located in the lowest circuit breaker panel beside the observers seat on the left side of the flight deck.) This directive effective November 2, 1961. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_61-21-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 61-21-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED All Model 188 Aircraft Subject: Compass Circuit Breakers Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/02/1961 Make: Lockheed Martin Corporation Model: 188A | 188C 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: 61-21-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 61-21-05 SUBJECT HEADING: LOCKHEED All Model 188 Aircraft ACTION: SUMMARY: DATES: Effective November 2, 1961. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 61-21-05 LOCKHEED: Amdt. 342 Part 507 Federal Register October 3, 1961. Applies to All Model 188 Aircraft. Compliance required as indicated. Several instances of inadvertent tripping of compass circuit breakers have occurred due to bumping the ganging bar by the occupant of the observers seat. Due to the effect of the loss of heading information upon operational safety, accomplishment of the following is required: Within the next 100 hours' time in service after the effective date of this AD, inspect the pilot's and copilot's compass circuit breakers, and if the circuit breakers are ganged together, either remove the ganging bars, or install a protective guard which precludes inadvertent operation of the ganging bar. (These circuit breakers are located in the lowest circuit breaker panel beside the observers seat on the left side of the flight deck.) This directive effective November 2, 1961. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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