AD 89-20-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Honeywell, Inc. | Flight Management System | Airworthiness Directives; HONEYWELL, INC.: Applicability: Sperry FMZ-800 Flight Management Systems (FMS), Model NZ-600, NZ-800, and NZ-900 Series Navigation Computers |
Unsafe Condition
FMS navigation errors caused by an erroneous omega/VLF sensor when using two or more inertial reference systems and one or more omega/VLF sensors.
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Required Actions
Add specified limitations to the FAA-approved Airplane Flight Manual or Supplement within 15 days after the effective date. Deselect the single operational omega/VLF sensor from one FMS navigation computer when navigating offshore beyond VOR/DME range with two FMS and one sensor. Deselect the sensor from the operating FMS if only one is functioning with multiple inertial systems.
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Compliance Time
Within 15 days after the effective date of this AD
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Affected Aircraft
Honeywell, Inc. Sperry FMZ-800 Flight Management Systems (FMS), Model NZ-600, NZ-800, and NZ-900 series Navigation Computers with part numbers 7004402-653, -654, -801, -803, -804, -805, -806, -811, -812, -813, -823, -824, -832, -833, -843, -844, -845, -901, -902, -903, -904, -905, and -906, installed with two or more inertial reference systems and one or more omega/VLF sensors.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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