AD 94-04-14
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Twin Commander Aircraft LLC | 500-S | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 500-U | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 680-FL(P) | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 680-W | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 681 | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 685 | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690 | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690A | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
| aircraft | Twin Commander Aircraft LLC | 690B | Airworthiness Directives: Twin Commander Aircraft Corporation 500, 680, 681, 685, and 690 Series Airplanes |
Unsafe Condition
Wing structural damage due to corrosion of the wing front spar lower cap, which could progress to failure if not detected.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Ultrasonically inspect the wing front spar lower cap for corrosion per SB No. 208A. Depending on corrosion severity, reinspect within 36, 30, or 12 calendar months, or replace the spar cap using specified modification kits before further flight.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 90 calendar days after the effective date of this AD or within 12 calendar months after the last inspection required by AD 91-08-09, whichever occurs later.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Twin Commander Aircraft LLC Models 500U, 680FL, 680FL(P), 680W, 500S (1755-3323), 681 (6001-6072), 685 (12000-12066), 690, 690A, 690B (11001-11566) without wing front spar lower cap replaced per specified modifications.
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
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.