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 |
| aircraft | The Boeing Company | 747-400D Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 747-400F Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 757-200 Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 757-200CB Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 757-200PF Series | Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes |
| aircraft | The Boeing Company | 757-300 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.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within 12 months of the effective date of this AD unless previously accomplished
AI-generated summary from the source AD text. Verify against the official source before acting.
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.
Federal Register Abstract
Radio Control Panels
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_91-21-12.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-21-12 Document Type: AD Final Rules Docket Number: 91-NM-86-AD Subject Heading: Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes Subject: Radio Control Panels Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/12/1991 Make: The Boeing Company Model: 737-100 Series | 737-200 Series | 737-200C Series | 737-300 Series | 737-400 Series | 737-500 Series...Show more Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 91-21-12 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-86-AD AMENDMENT: 39-8059 AD NUMBER: 91-21-12 SUBJECT HEADING: Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes ACTION: SUMMARY: DATES: Effective November 12, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-21-12 BOEING: Amendment 39-8059. Docket No. 91-NM-86-AD. Applicability: 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, certificated in any category. Compliance: Required within 12 months of the effective date of this AD unless previously accomplished. To prevent uncommanded frequency changes of the high frequency (HF) and very high frequency (VHF) radios, accomplish the following: (a) Remove the P/N 285U0037-104, -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. (b) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO. (c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. This amendment (39-8059, AD 91-21-12) becomes effective on November 12, 1991. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_91-21-12.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-21-12 Document Type: AD Final Rules Docket Number: 91-NM-86-AD Subject Heading: Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes Subject: Radio Control Panels Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/12/1991 Make: The Boeing Company Model: 737-100 Series | 737-200 Series | 737-200C Series | 737-300 Series | 737-400 Series | 737-500 Series...Show more Product Type: Aircraft Product Subtype: Large Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 91-21-12 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-86-AD AMENDMENT: 39-8059 AD NUMBER: 91-21-12 SUBJECT HEADING: Airworthiness Directives; BOEING Model 737, 757, and 747-400 Series Airplanes ACTION: SUMMARY: DATES: Effective November 12, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-21-12 BOEING: Amendment 39-8059. Docket No. 91-NM-86-AD. Applicability: 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, certificated in any category. Compliance: Required within 12 months of the effective date of this AD unless previously accomplished. To prevent uncommanded frequency changes of the high frequency (HF) and very high frequency (VHF) radios, accomplish the following: (a) Remove the P/N 285U0037-104, -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. (b) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO. (c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. This amendment (39-8059, AD 91-21-12) becomes effective on November 12, 1991. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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