AD 77-17-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Transcontinental and Western Air, Inc. | Army B-17F | BOEING Model B-17F & G Airplanes |
| aircraft | Transcontinental and Western Air, Inc. | Army B-17G | BOEING Model B-17F & G Airplanes |
Unsafe Condition
Cracking in the rear spar lower cap center section, part numbers 75-3425-2 or 85-3425-2, around the bolt holes in both the forward and aft walls of the tube.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove the three most inboard bolts from the 14-bolt pattern, inspect using eddy current or boroscope with dye penetrants for cracks. Replace or repair if cracks found, reinspect at intervals not exceeding 50 hours or 12 months. Reinspect reamed holes within 1500 flight hours and revert to 150-hour/12-month intervals afterward. New replacement chords must be inspected within 2500 flight hours and follow subsequent intervals.
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Compliance Time
Within the next 25 hours' time-in-service or within 6 months after the effective date of this AD, whichever comes first, unless already accomplished within the last 25 hours or 6 months.
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Affected Aircraft
BOEING Model B-17F & G airplanes certified in all categories.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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