AD 80-18-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sperry Flight Systems | Flight Director Systems | Airworthiness Directives; SPERRY FLIGHT SYSTEMS, AVIONICS DIVISION: Applies to Flight Director Systems installed on aircraft certified in all categories |
Unsafe Condition
Possible erroneous presentation of glide slope information due to incorrect +28V bias voltage connection into receptacle J1-b on Sperry HSI RD 044 or RD 444.
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Required Actions
Revise the circuit hook-up to move the +28V dc bias voltage source from the Flight Director Circuit Breaker to the +28V dc circuit breaker supplying the glide slope receiver. Special flight permits may be issued under FAR 21.197 and 21.199 to operate to a base for modification. Alternative actions providing equivalent safety may be approved by the FAA.
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Compliance Time
Within the next 100 hours' time in service from the effective date of this AD, or within 60 days from the effective date of this AD, whichever occurs sooner
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Affected Aircraft
Flight Director Systems (STARS) installed on aircraft certified in all categories, including Sperry HSI RD 044 (P/N 2592920-44) and RD 444 (P/N 2592920-444). Beech Model 90, 100, and 200 aircraft with STARS installations are specifically referenced.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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