AD 59-13-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | DC-6A | Airworthiness Directives; DOUGLAS DC-6A and DC-6B |
| aircraft | The Boeing Company | DC-6B | Airworthiness Directives; DOUGLAS DC-6A and DC-6B |
Unsafe Condition
Cracks have been reported in the lower front spar cap at wing Station 30 at the intersection of the lower front spar cap aft tang and wing-to-fuselage attach angle. Cracks could also occur in the lower center spar cap due to structural similarity.
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Required Actions
Inspect lower front spar caps within 200 flight-hours of the nearest maintenance inspection period if not inspected within the last 1,250 flying hours. Subsequent inspections must occur every 1,250 flying hours. Enlarge holes and install new attachments using KIT 'A' (Douglas SB A-821 or equivalent) during the first 1,250-hour inspection and next overhaul. If cracks are found, perform temporary rework with KIT 'B' and repeat inspections every 1,250 hours for up to 3,200 flight-hours, then permanent rework with KIT 'C'. All aircraft must complete permanent rework within 6,400 flying hours. After KIT 'C', revert to 3,200-hour inspection intervals.
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Compliance Time
Compliance required as indicated.
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Affected Aircraft
Douglas DC-6A (serial numbers 43296, 43297, 43817-43819, 43839-43841, 44063, 44064, 44069-44073, 44076, 44257) and DC-6B (serial numbers 43257-43259, 43261-43276, 43291, 43292, 43298-43300, 43518-43537, 43539-43547, 43549-43555, 43557-43564, 43738-43741, 43743-43746, 43748-43750, 43820-43822, 43824-43826, 43828-43834, 43836, 43837, 43842, 43844-43847, 44056-44062, 44080-44083, 44087-44089, 44102-44113, 44165-44168, 44251). Excludes serial numbers 43548 and 43152 under U.S. registry.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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