AD 56-25-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Aircraft Corporation | 1049-54 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 1049C-55 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 149-46 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 49-46 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 649-79 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 649A-79 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 749-79 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
| aircraft | Lockheed Aircraft Corporation | 749A-79 | LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft |
Unsafe Condition
Flap asymmetry during extension, leading to potential loss of control due to uncommanded flap extension on one side of the aircraft.
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Required Actions
Install a hydraulic power shut-off mechanism to automatically disable flap actuating motors when asymmetry occurs, as per Lockheed Service Bulletins 49/SB-794 (49/749 Series) and 1049/SB-2270 (1049 Series).
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Compliance Time
First block overhaul following receipt of parts or by March 1, 1958, whichever occurs first.
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Affected Aircraft
Lockheed Models 49, 149, 649, 649A, 749, 749A; Model 1049 Serial Numbers 4001-4024; Model 1049C Serial Numbers 4501-4520 and 4523-4538.
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Federal Register Abstract
Flap Symmetry
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_56-25-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-25-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft Subject: Flap Symmetry Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Lockheed Aircraft Corporation Model: 1049-54 | 1049C-55 | 149-46 | 49-46 | 649-79 | 649A-79 | 749-79 | 749A-79 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: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 56-25-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-25-04 SUBJECT HEADING: LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-25-04 LOCKHEED: Applies to All Models 49, 149, 649, 649A, 749, 749A Aircraft; Model 1049 Serial Numbers 4001 Through 4024; Model 1049C Serial Numbers 4501 Through 4520 and 4523 Through 4538. Compliance required at first block overhaul following receipt of parts or by March 1, 1958, whichever occurs first. In view of the continuing series of incidents wherein flaps extend on one side of the aircraft out of symmetry with the other side, a means shall be installed which will automatically shut off the hydraulic power to the flap actuating motors whenever an asymmetrical condition exists. One method of accomplishing this means is described in Lockheed Service Bulletin No. 49/SB-794 for the 49/749 Series and No. 1049/SB-2270 for the 1049 Series. FOOTER:
Document Text
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AD Final Rules - DRS_56-25-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-25-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft Subject: Flap Symmetry Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Lockheed Aircraft Corporation Model: 1049-54 | 1049C-55 | 149-46 | 49-46 | 649-79 | 649A-79 | 749-79 | 749A-79 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: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 56-25-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-25-04 SUBJECT HEADING: LOCKHEED Models 49, 149, 649, 649A, 749, 749A, 1049, and 1049C Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-25-04 LOCKHEED: Applies to All Models 49, 149, 649, 649A, 749, 749A Aircraft; Model 1049 Serial Numbers 4001 Through 4024; Model 1049C Serial Numbers 4501 Through 4520 and 4523 Through 4538. Compliance required at first block overhaul following receipt of parts or by March 1, 1958, whichever occurs first. In view of the continuing series of incidents wherein flaps extend on one side of the aircraft out of symmetry with the other side, a means shall be installed which will automatically shut off the hydraulic power to the flap actuating motors whenever an asymmetrical condition exists. One method of accomplishing this means is described in Lockheed Service Bulletin No. 49/SB-794 for the 49/749 Series and No. 1049/SB-2270 for the 1049 Series. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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