AD 91-18-21
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Viking Air Limited | DHC-7-1 | Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-100 | Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-101 | Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-102 | Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-103 | Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes |
Unsafe Condition
Jamming of the flaps and reduction of airplane controllability due to failure of the flap track No. 4 forward support fittings.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the left- and right-hand wing flap track No. 4 forward support fittings in accordance with de Havilland Service Bulletin No. 7-27-37. An alternative method of compliance or adjustment of the compliance time may be used if approved by the Manager, New York Aircraft Certification Office.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within one year after 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 Of Canada, Ltd., De Havilland Division Model DHC-7 series airplanes with serial numbers 53 through 57, 59, and 60.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Flap Track Support Fittings
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_91-18-21.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-18-21 Document Type: AD Final Rules Docket Number: 91-NM-43-AD Subject Heading: Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes Subject: Flap Track Support Fittings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 10/15/1991 Make: Viking Air Limited Model: DHC-7-1 | DHC-7-100 | DHC-7-101 | DHC-7-102 | DHC-7-103 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: 91-18-21 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-43-AD AMENDMENT: 39-8025 AD NUMBER: 91-18-21 SUBJECT HEADING: Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes ACTION: SUMMARY: DATES: Effective October 15, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-18-21 BOEING OF CANADA, LTD., DE HAVILLAND DIVISION: Amendment 39- 8025. Docket No. 91-NM-43-AD. Applicability: Model DHC-7 series airplanes; Serial Numbers 53 through 57, 59, and 60; certificated in any category. Compliance: Required within one year after the effective date of this AD, unless previously accomplished. To prevent jamming of the flaps and reduction of airplane controllability, accomplish the following: (a) Replace the left- and right-hand wing flap track No. 4 forward support fittings in accordance with the Accomplishment Instructions of de Havilland Service Bulletin No. 7-27-37, dated October 28, 1981. (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, New York Aircraft Certification Office (ACO), ANE-170, FAA, New England Region. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, New York Aircraft Certification Office. (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. (d) The replacement requirements shall be done in accordance with de Havilland Service Bulletin No. 7-27-37, dated October 26, 1981. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing of Canada, Ltd., de Havilland Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, Renton, Washington; at the FAA, New England Region, New York Aircraft Certification Office, 181 S. Franklin Avenue, Room 202, Valley Stream, New York; or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C. This amendment (39-8025, AD 91-18-21) becomes effective on October 15, 1991. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_91-18-21.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 91-18-21 Document Type: AD Final Rules Docket Number: 91-NM-43-AD Subject Heading: Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes Subject: Flap Track Support Fittings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 10/15/1991 Make: Viking Air Limited Model: DHC-7-1 | DHC-7-100 | DHC-7-101 | DHC-7-102 | DHC-7-103 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: 91-18-21 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: 91-NM-43-AD AMENDMENT: 39-8025 AD NUMBER: 91-18-21 SUBJECT HEADING: Airworthiness Directives; Boeing Of Canada, Ltd., De Havilland Division Model DHC-7 Series Airplanes ACTION: SUMMARY: DATES: Effective October 15, 1991. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 91-18-21 BOEING OF CANADA, LTD., DE HAVILLAND DIVISION: Amendment 39- 8025. Docket No. 91-NM-43-AD. Applicability: Model DHC-7 series airplanes; Serial Numbers 53 through 57, 59, and 60; certificated in any category. Compliance: Required within one year after the effective date of this AD, unless previously accomplished. To prevent jamming of the flaps and reduction of airplane controllability, accomplish the following: (a) Replace the left- and right-hand wing flap track No. 4 forward support fittings in accordance with the Accomplishment Instructions of de Havilland Service Bulletin No. 7-27-37, dated October 28, 1981. (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, New York Aircraft Certification Office (ACO), ANE-170, FAA, New England Region. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, New York Aircraft Certification Office. (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. (d) The replacement requirements shall be done in accordance with de Havilland Service Bulletin No. 7-27-37, dated October 26, 1981. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing of Canada, Ltd., de Havilland Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, Renton, Washington; at the FAA, New England Region, New York Aircraft Certification Office, 181 S. Franklin Avenue, Room 202, Valley Stream, New York; or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C. This amendment (39-8025, AD 91-18-21) becomes effective on October 15, 1991. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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