AD 80-21-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Textron Aviation Inc. | 77 | Airworthiness Directives; Beech Model 77 Airplanes |
Unsafe Condition
Thread damage on the four bolts and nuts attaching the engine mount to the firewall could compromise the structural integrity of the engine mount attachment.
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Required Actions
Remove and inspect the four bolts and nuts for thread damage. Replace damaged bolts and nuts with new parts per Table I. Ream attachment holes to .375/.379 inch diameter, clean parts, install bolts with specified torque, and report damaged bolts via FAA Form 8330-2 within five days.
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Compliance Time
Prior to further flight
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Affected Aircraft
Beech Model 77 airplanes with serial numbers WA-1 through WA-156, WA-158 through WA-161, WA-163 through WA-171, WA-173, WA-174, WA-177, and WA-178.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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