AD 89-10-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | ATR - GIE Avions de Transport R gional | ATR42-200 | Airworthiness Directives; AEROSPATIALE Model ATR-42 Series Airplanes |
| aircraft | ATR - GIE Avions de Transport R gional | ATR42-300 | Airworthiness Directives; AEROSPATIALE Model ATR-42 Series Airplanes |
| aircraft | ATR - GIE Avions de Transport R gional | ATR42-320 | Airworthiness Directives; AEROSPATIALE Model ATR-42 Series Airplanes |
| aircraft | ATR - GIE Avions de Transport R gional | ATR42-500 | Airworthiness Directives; AEROSPATIALE Model ATR-42 Series Airplanes |
Unsafe Condition
Unauthorized mixing of Honeywell-Sperry Symbol Generator Units (SGU) and Attitude Heading Reference Units (AHRU) may cause improper functioning of navigation equipment and incompatible equipment combinations.
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Required Actions
Within 10 days after the effective date, inspect SGUs and AHRUs for unauthorized mixing, correct prior to further flight, and insert AFM limitations. Within 120 days, replace Digital Air Data Computer (DADC), Attitude Heading Reference System (AHRS), and SGUs per specified service bulletins.
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Compliance Time
Within 10 days after the effective date of this AD, and within 120 days after the effective date of this AD
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Affected Aircraft
AEROSPATIALE Model ATR-42 series airplanes, Serial Numbers 003 through 093, certificated in any category.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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