AD 58-01-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Twin Commander Aircraft LLC | 520 | Airworthiness Directives; Aero Commander Models 520, 560, 560A, 560E and 680 Aircraft |
| aircraft | Twin Commander Aircraft LLC | 560 | Airworthiness Directives; Aero Commander Models 520, 560, 560A, 560E and 680 Aircraft |
| aircraft | Twin Commander Aircraft LLC | 560-A | Airworthiness Directives; Aero Commander Models 520, 560, 560A, 560E and 680 Aircraft |
| aircraft | Twin Commander Aircraft LLC | 560-E | Airworthiness Directives; Aero Commander Models 520, 560, 560A, 560E and 680 Aircraft |
| aircraft | Twin Commander Aircraft LLC | 680 | Airworthiness Directives; Aero Commander Models 520, 560, 560A, 560E and 680 Aircraft |
Unsafe Condition
Failures of the vent lines located above the nacelle upper fire shield have resulted in the release of fuel and/or fuel vapor in the engine compartment, creating a dangerous fire hazard due to interference or chafing between wing structure and the carburetor return and fuel tank vent lines. Failures also occurred at the carburetor vapor return elbow located in the upper fire shield.
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Required Actions
Replace portions of the carburetor vapor vent and fuel tank vent lines above the upper fire shield with flexible hose assemblies (P/N 6630086-237, 6630086-223, 6630086-229 or equivalent). Securely fasten the hose assemblies to the wing structure with hose clamps. Replace existing carburetor vapor return line elbows with antirotation fittings (P/N 5630085-21, 5630085-29) and install upper fire shield channels (P/N 5630086-25, 5630086-23).
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Compliance Time
as soon as possible but not later than July 1, 1958
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Affected Aircraft
Twin Commander Aircraft LLC models 520, 560, 560A, 560E, and 680 with serial numbers 231 through 580 except 315, 466, 471, 485, 492, 509, 523, 547, 568, 570, 572, 574, 576, 579
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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