AD 2001-21-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | McDonnell Douglas | MD-11 | Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes |
Unsafe Condition
Suspected defective multiplexers could lead to loss of airspeed and altitude indications on both primary flight displays in the cockpit, and/or loss or degradation of the autopilot functionality, and consequent failure of the data busses.
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Required Actions
Inspect to verify that modification 'AS' is on the front and rear identification plates of flight management computers (FMC-1 and FMC-2). If modification 'AS' is installed, test the FMCs to ensure they are operational and install new software to reidentify them as part number 4059050-912. If modification 'AS' is not installed, follow applicable corrective actions.
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Compliance Time
Within 90 days after the effective date of this AD.
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Affected Aircraft
McDonnell Douglas Model MD-11 series airplanes with manufacturer's fuselage numbers 0447 through 0552 inclusive, and 0554 through 0621 inclusive, certificated in any category.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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