AD 71-21-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Viking Air Limited | DHC-6-1 | Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes |
| aircraft | Viking Air Limited | DHC-6-100 | Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes |
| aircraft | Viking Air Limited | DHC-6-200 | Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes |
| aircraft | Viking Air Limited | DHC-6-300 | Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes |
Unsafe Condition
Loss of AC power system due to a fault in an AC circuit causing total power loss.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Comply with Service Bulletin 6/263 (Rev B) instructions 1 and 2(a) through 2(e), replace slow-blow fuses with Littlefuse or Bussman types as specified, and replace non-compliant inverters prior to further flight.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 250 hours' time in service after the effective date of this AD unless already accomplished
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Affected Aircraft
de Havilland Model DHC-6 Series Airplanes, Serial Numbers 6 through 289 with Flitetronic Type PC 15 or PC 15A Inverters.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Loss of AC Power System
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_71-21-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-21-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes Subject: Loss of AC Power System Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 10/12/1971 Make: Viking Air Limited Model: DHC-6-1 | DHC-6-100 | DHC-6-200 | DHC-6-300 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 71-21-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1310 AD NUMBER: 71-21-07 SUBJECT HEADING: Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes ACTION: SUMMARY: DATES: Effective October 12, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-21-07 de HAVILLAND: Amendment 39-1310. Applies to de Havilland Model DHC- 6 Airplanes, Serial Numbers 6 through 289 certificated in all categories and incorporating Flitetronic Type PC 15 or PC 15A Inverters. Compliance required within the next 250 hours' time in service after the effective date of this AD unless already accomplished. To prevent a total loss of AC power in the event of a fault occurring in an AC circuit, accomplish the following: (a) Comply with Accomplishment Instructions 1 and 2 (a) through 2(e) of de Havilland Service Bulletin No. 6/263 dated 5 October 1970, Revision B dated 29 January 1971. (b) Remove slow-blow fuses not replaced in (a) and replace with: (1) Littlefuse type 312 of the same rating for the 26-volt supply except that ratings greater than 2 amps shall be replaced with Littlefuse 312002. (2) Littlefuse type 312 or Bussman type MB of the same rating for the 115 Volt supply, except that ratings greater than 1 amp shall be replaced with Littlefuse 312001 or Bussman MB01. (c) Comply with Accomplishment Instructions 3 through 6 of de Havilland Service Bulletin No. 6/263 dated 5 October 1970, Revision B dated 29 January 1971 for PC 15 and PC 15A inverter without a suffix letter after the serial number. Inverters which do not meet the requirements of the overload function test must be replaced, prior to further flight, with an inverter with a suffix letter after the serial number. Equivalent methods may be used provided they are approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Upon request with substantiation data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. This amendment is effective October 12, 1971. FOOTER:
Document Text
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AD Final Rules - DRS_71-21-07.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-21-07 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes Subject: Loss of AC Power System Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 10/12/1971 Make: Viking Air Limited Model: DHC-6-1 | DHC-6-100 | DHC-6-200 | DHC-6-300 Product Type: Aircraft Product Subtype: Small 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: 71-21-07 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1310 AD NUMBER: 71-21-07 SUBJECT HEADING: Airworthiness Directives; de Havilland Model DHC- 6 Series Airplanes ACTION: SUMMARY: DATES: Effective October 12, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-21-07 de HAVILLAND: Amendment 39-1310. Applies to de Havilland Model DHC- 6 Airplanes, Serial Numbers 6 through 289 certificated in all categories and incorporating Flitetronic Type PC 15 or PC 15A Inverters. Compliance required within the next 250 hours' time in service after the effective date of this AD unless already accomplished. To prevent a total loss of AC power in the event of a fault occurring in an AC circuit, accomplish the following: (a) Comply with Accomplishment Instructions 1 and 2 (a) through 2(e) of de Havilland Service Bulletin No. 6/263 dated 5 October 1970, Revision B dated 29 January 1971. (b) Remove slow-blow fuses not replaced in (a) and replace with: (1) Littlefuse type 312 of the same rating for the 26-volt supply except that ratings greater than 2 amps shall be replaced with Littlefuse 312002. (2) Littlefuse type 312 or Bussman type MB of the same rating for the 115 Volt supply, except that ratings greater than 1 amp shall be replaced with Littlefuse 312001 or Bussman MB01. (c) Comply with Accomplishment Instructions 3 through 6 of de Havilland Service Bulletin No. 6/263 dated 5 October 1970, Revision B dated 29 January 1971 for PC 15 and PC 15A inverter without a suffix letter after the serial number. Inverters which do not meet the requirements of the overload function test must be replaced, prior to further flight, with an inverter with a suffix letter after the serial number. Equivalent methods may be used provided they are approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Upon request with substantiation data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. This amendment is effective October 12, 1971. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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