AD 71-16-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Viking Air Limited | DHC-6-1 | Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft |
| aircraft | Viking Air Limited | DHC-6-100 | Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft |
| aircraft | Viking Air Limited | DHC-6-200 | Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft |
| aircraft | Viking Air Limited | DHC-6-300 | Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft |
Unsafe Condition
Separation of the flapper valve seal in fuel cells No. 4 and No. 5 could cause engine flameout due to fuel starvation.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace No. 4 and No. 5 flapper valve assemblies, P/N C6PF1026-3, with new like parts and repeat replacement every 12 months until DHC modification 6/1406 is incorporated per Service Bulletin 6/269 or an approved equivalent.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 30 days after the effective date of this AD for aircraft with 12 months or more service from first flight; within 30 days after accumulating 12 months' service for those with less.
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Affected Aircraft
de Havilland Model DHC-6 Series Aircraft, Serial Numbers 1 through 299 inclusive.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Fuel Cell Flapper Valves
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_71-16-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-16-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft Subject: Fuel Cell Flapper Valves Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/03/1971 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Model: DHC-6-1 | DHC-6-100 | DHC-6-200 | DHC-6-300 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 71-16-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1250 AD NUMBER: 71-16-01 SUBJECT HEADING: Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft ACTION: SUMMARY: DATES: Effective August 3, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-16-01 de HAVILLAND AIRCRAFT of CANADA LTD: Amdt. 39-1250. Applies to de Havilland Type DHC-6 Aircraft, Serial Numbers 1 through 299, inclusive. Compliance required, unless already accomplished, within 30 days after the effective date of this AD for aircraft which have been in service for 12 months or more from the date of first flight. For aircraft which have been in service less than 12 months, compliance required within 30 days after the accumulation of 12 months' service. To preclude the possibility of engine flameout due to fuel starvation in the event of separation of the flapper valve seal in fuel cells No. 4 and No. 5, replace No. 4 and No. 5 flapper valve assemblies, P/N C6PF1026-3, with new like parts and repeat replacement thereafter at 12- month intervals until such time as DHC modifications 6/1406 is incorporated in accordance with instructions contained in DHC Service Bulletin No. 6/269, dated February 19, 1971, or an equivalent modification approved by the Chief, Engineering & Manufacturing Branch, Federal Aviation Administration, Eastern Region. This amendment is effective August 3, 1971. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_71-16-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-16-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft Subject: Fuel Cell Flapper Valves Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/03/1971 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: 71-16-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1250 AD NUMBER: 71-16-01 SUBJECT HEADING: Airworthiness Directives; de Havilland Model DHC-6 Series Aircraft ACTION: SUMMARY: DATES: Effective August 3, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-16-01 de HAVILLAND AIRCRAFT of CANADA LTD: Amdt. 39-1250. Applies to de Havilland Type DHC-6 Aircraft, Serial Numbers 1 through 299, inclusive. Compliance required, unless already accomplished, within 30 days after the effective date of this AD for aircraft which have been in service for 12 months or more from the date of first flight. For aircraft which have been in service less than 12 months, compliance required within 30 days after the accumulation of 12 months' service. To preclude the possibility of engine flameout due to fuel starvation in the event of separation of the flapper valve seal in fuel cells No. 4 and No. 5, replace No. 4 and No. 5 flapper valve assemblies, P/N C6PF1026-3, with new like parts and repeat replacement thereafter at 12- month intervals until such time as DHC modifications 6/1406 is incorporated in accordance with instructions contained in DHC Service Bulletin No. 6/269, dated February 19, 1971, or an equivalent modification approved by the Chief, Engineering & Manufacturing Branch, Federal Aviation Administration, Eastern Region. This amendment is effective August 3, 1971. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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