AD 74-20-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Leigh Systems | Emergency Locator Transmitter | Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series |
| appliance | Leigh Systems | Emergency Locator Transmitter | Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series |
Unsafe Condition
Chemical corrosion may cause failure of the Emergency Locator Transmitter (ELT) to operate or result in inadvertent activation, jamming the emergency frequencies of 121.5 MHz and 243.0 MHz.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Conduct a visual inspection for corrosion per Leigh Systems' Service Bulletin No. 003A or approved equivalent. If no corrosion is found, verify ELT transmission compliance. If corrosion exists or transmission fails, replace with an approved serviceable unit or TSO-approved unit before next flight except for ferry flights under FAR 91.52(e)(2).
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 90 days and thereafter at each additional 60 day interval after the effective date of this Airworthiness Directive.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Leigh Systems Emergency Locator Transmitter Sharc 7 Series, serial numbers all through 163500 equipped with lithium batteries.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Emergency Locator Transmitter
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_74-20-10.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-20-10 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series Subject: Emergency Locator Transmitter Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/30/1977 Make: Leigh Systems Model: Emergency Locator Transmitter Product Type: Appliance Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 74-20-10 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3104 AD NUMBER: 74-20-10 SUBJECT HEADING: Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series ACTION: SUMMARY: DATES: Effective December 30, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-20-10 LEIGH SYSTEMS: Amendment 39-1976 as amended by Amendment 39-2038, 39-2732, and 39-3000 is further amended by Amendment 39-3104. Emergency Locator Transmitter Leigh Systems Sharc 7 Series. Applies to all Leigh Systems Sharc 7 Emergency Locator Transmitters Serial Numbers all through 163500 equipped with lithium batteries. Compliance required as indicated. As a result of chemical corrosion resulting in either failure of the Emergency Locator Transmitter (ELT) to operate or inadvertent activation, jamming the emergency frequencies of 121.5 MHz and 243.0 MHz accomplish the following: Within the next 90 days and thereafter at each additional 60 day interval after the effective date of this Airworthiness Directive, accomplish the following: 1. Deleted. 2. Conduct a visual inspection for evidence of corrosion in accordance with photo reproduction which is part of Leigh System's Service Bulletin No. 003A, dated May 15, 1974, or equivalent inspections approved by Chief, Engineering and Manufacturing Branch, FAA Eastern Region. 3. If no corrosion is found, prior to reinstalling, determine ELT transmits properly. ELT transmissions are authorized in the first five minutes of any hour or at other times if coordinated with the nearest FAA Tower or Flight Service Station for a total of three audio sweeps (Ref. FAA Advisory Circular 00-35A or 20-81). 4. If corrosion is found or if the ELT does not transmit properly, replace with an approved serviceable unit which has been inspected in accordance with paragraph 2; or replace with another TSO approved unit, prior to the next flight except that a ferry flight may be conducted in accordance with FAR 91.52(e)(2). NOTE: ELT's equipped with lithium batteries may be identified by inspecting the identification tags. Units marked in the weight range of 1.5 to 2.0 lbs. are lithium batteries. Amendment 39-1976 was effective October 1, 1974. Amendment 39-2038 was effective December 9, 1974. Amendment 39-2732 was effective September 29, 1976. Amendment 39-3000 was effective August 10, 1977. This Amendment 39-3104 is effective December 30, 1977. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_74-20-10.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-20-10 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series Subject: Emergency Locator Transmitter Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 12/30/1977 Make: Leigh Systems Model: Emergency Locator Transmitter Product Type: Appliance Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 74-20-10 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3104 AD NUMBER: 74-20-10 SUBJECT HEADING: Airworthiness Directives; LEIGH SYSTEMS: Emergency Locator Transmitter Leigh Systems Sharc 7 Series ACTION: SUMMARY: DATES: Effective December 30, 1977. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-20-10 LEIGH SYSTEMS: Amendment 39-1976 as amended by Amendment 39-2038, 39-2732, and 39-3000 is further amended by Amendment 39-3104. Emergency Locator Transmitter Leigh Systems Sharc 7 Series. Applies to all Leigh Systems Sharc 7 Emergency Locator Transmitters Serial Numbers all through 163500 equipped with lithium batteries. Compliance required as indicated. As a result of chemical corrosion resulting in either failure of the Emergency Locator Transmitter (ELT) to operate or inadvertent activation, jamming the emergency frequencies of 121.5 MHz and 243.0 MHz accomplish the following: Within the next 90 days and thereafter at each additional 60 day interval after the effective date of this Airworthiness Directive, accomplish the following: 1. Deleted. 2. Conduct a visual inspection for evidence of corrosion in accordance with photo reproduction which is part of Leigh System's Service Bulletin No. 003A, dated May 15, 1974, or equivalent inspections approved by Chief, Engineering and Manufacturing Branch, FAA Eastern Region. 3. If no corrosion is found, prior to reinstalling, determine ELT transmits properly. ELT transmissions are authorized in the first five minutes of any hour or at other times if coordinated with the nearest FAA Tower or Flight Service Station for a total of three audio sweeps (Ref. FAA Advisory Circular 00-35A or 20-81). 4. If corrosion is found or if the ELT does not transmit properly, replace with an approved serviceable unit which has been inspected in accordance with paragraph 2; or replace with another TSO approved unit, prior to the next flight except that a ferry flight may be conducted in accordance with FAR 91.52(e)(2). NOTE: ELT's equipped with lithium batteries may be identified by inspecting the identification tags. Units marked in the weight range of 1.5 to 2.0 lbs. are lithium batteries. Amendment 39-1976 was effective October 1, 1974. Amendment 39-2038 was effective December 9, 1974. Amendment 39-2732 was effective September 29, 1976. Amendment 39-3000 was effective August 10, 1977. This Amendment 39-3104 is effective December 30, 1977. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.