AD 91-09-08
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
Structural fatigue failure of the fuselage longeron at the rear spar frame and the lower wing/outboard nacelle joint.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform radiographic inspections for cracks at the rear spar frame and wing/outboard nacelle joint per specified service bulletins. If cracks found, repair and incorporate modifications 7/1622 and 7/1645. Repeat inspections every 1,000 hours time-in-service if no cracks. Reinforce structures within 2 years of AD effective date.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 25 hours time-in-service after October 31, 1980, unless previously accomplished within the last 975 hours time-in-service. For paragraph C, within 2 years after the effective date of this AD (May 28, 1991).
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, certificated in any category, serial numbers 1 through 14 and 17.
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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