AD 94-04-12
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Twin Commander Aircraft LLC | 685 | Airworthiness Directives: Twin Commander Aircraft Corporation Models 685, 690, 690A, and 690B Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690 | Airworthiness Directives: Twin Commander Aircraft Corporation Models 685, 690, 690A, and 690B Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690A | Airworthiness Directives: Twin Commander Aircraft Corporation Models 685, 690, 690A, and 690B Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690B | Airworthiness Directives: Twin Commander Aircraft Corporation Models 685, 690, 690A, and 690B Airplanes |
Unsafe Condition
Failure of the wing structure caused by a cracked wing front spar lower cap or cracked or deformed wing rib at Wing Station (WS) 39.
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Required Actions
Modify the wing ribs at WS 39 per Twin Commander SB No. 211, Revision 1. Eddy current inspect the wing front spar lower cap and lower wing stringer No. 7 at WS 39 for cracks or corrosion. Treat corrosion with inhibitor if less than specified limits, or replace the spar cap if cracks or excessive corrosion are found, following specified kits or STC.
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Compliance Time
within the next 50 hours time-in-service after the effective date of this AD, unless already accomplished
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Affected Aircraft
Twin Commander Aircraft LLC Models 685 (serial numbers 12000 through 12066), 690, 690A, and 690B (serial numbers 11001 through 11566) that have not had the wing front spar lower cap replaced per specified procedures.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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