AD 91-21-12
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-100 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-200 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-200C Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-600 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-700 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 737-800 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
Unsafe Condition
Uncommanded frequency changes of the high frequency (HF) and very high frequency (VHF) radios due to the use of Boeing part number 285U0037-104, -105, -201, -202, or -203 series radio control panels.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove the P/N 285U0037-105, -201, -202, or -203 series radio control panels and replace them with panels approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.
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Compliance Time
within 12 months of the effective date of this AD unless previously accomplished
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Affected Aircraft
Boeing Model 737, 757, and 747-400 series airplanes equipped with Boeing part number (P/N) 285U0037-104, -105, -201, -202, or -203 series radio control panels.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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