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.
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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.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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