AD 56-01-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Aero Spacelines, Incorporated | 377 | BOEING Model 377 Aircraft |
| aircraft | Aero Spacelines, Incorporated | 377MG | BOEING Model 377 Aircraft |
| aircraft | Aero Spacelines, Incorporated | 377SGT | BOEING Model 377 Aircraft |
Unsafe Condition
Cracks discovered at wing spar splice bolt holes, specifically at No. 1 bolt hole in each rear spar Station 246 joint and Nos. 1 and 6 bolt holes in each front and rear spar Station 510 joints, as well as outboard bolt holes in each front and rear spar Station 47.75 joints.
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Required Actions
Inspect No. 1 bolt hole in each rear spar Station 246 joint and Nos. 1 and 6 bolt holes in each front and rear spar Station 510 joints at the next basic check period (not exceeding 2,500 flight hours). Use borescope or equivalent method. If cracks found, rework splice per Boeing Service Letter No. 289. Additionally, inspect outboard bolt holes in each front and rear spar Station 47.75 joints within next 500 flight hours (if not recently done) using borescope; repair cracks per Boeing Instructions.
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Compliance Time
At the next basic check period and subsequent thereto, at each basic check period but not to exceed an interval of 2,500 hours flight time. Additionally, within the next 500 flight hours unless recently accomplished.
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Affected Aircraft
BOEING Model 377 Aircraft, including 377, 377MG, 377SGT models, all serial numbers.
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Federal Register Abstract
Wing Spar Splice Bolt Holes
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_56-01-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-01-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: BOEING Model 377 Aircraft Subject: Wing Spar Splice Bolt Holes Status: Current Citation: This information is not available. Citation Publish Date: 12/04/1956 Effective Date: Make: Aero Spacelines, Incorporated Model: 377 | 377MG | 377SGT Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: unable to find issue date. AIRWORTHINESS DIRECTIVES FINAL RULES: 56-01-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-01-02 SUBJECT HEADING: BOEING Model 377 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-01-02 BOEING: Applies to All model 377 Aircraft. Compliance required as indicated. As a result of cracks discovered at wing spar splice bolt holes the following inspection and possible rework is required. At the next basic check period and subsequent thereto, at each basic check period but not to exceed an interval of 2,500 hours flight time, the No. 1 bolt hole in each rear spar Station 246 joint and Nos. 1 and 6 bolt holes in each front and rear spar Station 510 joints shall be carefully inspected by use of borescope or equivalent method. If cracks are found, the splice should be reworked in accordance with instructions contained in Boeing Service Letter No. 289. Within the next 500 flight hours, unless recently accomplished, the outboard bolt holes in each front and rear spar Station 47.75 joints shall be inspected for cracks by use of borescope or equivalent method. If cracks are found, they shall be repaired in accordance with Boeing Instructions. This supersedes AD 55-23-01. FOOTER:
Document Text
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AD Final Rules - DRS_56-01-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-01-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: BOEING Model 377 Aircraft Subject: Wing Spar Splice Bolt Holes Status: Current Citation: This information is not available. Citation Publish Date: 12/04/1956 Effective Date: Make: Aero Spacelines, Incorporated Model: 377 | 377MG | 377SGT Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: unable to find issue date. AIRWORTHINESS DIRECTIVES FINAL RULES: 56-01-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-01-02 SUBJECT HEADING: BOEING Model 377 Aircraft ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 56-01-02 BOEING: Applies to All model 377 Aircraft. Compliance required as indicated. As a result of cracks discovered at wing spar splice bolt holes the following inspection and possible rework is required. At the next basic check period and subsequent thereto, at each basic check period but not to exceed an interval of 2,500 hours flight time, the No. 1 bolt hole in each rear spar Station 246 joint and Nos. 1 and 6 bolt holes in each front and rear spar Station 510 joints shall be carefully inspected by use of borescope or equivalent method. If cracks are found, the splice should be reworked in accordance with instructions contained in Boeing Service Letter No. 289. Within the next 500 flight hours, unless recently accomplished, the outboard bolt holes in each front and rear spar Station 47.75 joints shall be inspected for cracks by use of borescope or equivalent method. If cracks are found, they shall be repaired in accordance with Boeing Instructions. This supersedes AD 55-23-01. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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