AD 81-03-51
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Viking Air Limited | DHC-7-1 | Airworthiness Directives; DeHavilland Model DHC-7 Airplanes |
| aircraft | Viking Air Limited | DHC-7-100 | Airworthiness Directives; DeHavilland Model DHC-7 Airplanes |
| aircraft | Viking Air Limited | DHC-7-101 | Airworthiness Directives; DeHavilland Model DHC-7 Airplanes |
| aircraft | Viking Air Limited | DHC-7-102 | Airworthiness Directives; DeHavilland Model DHC-7 Airplanes |
| aircraft | Viking Air Limited | DHC-7-103 | Airworthiness Directives; DeHavilland Model DHC-7 Airplanes |
Unsafe Condition
Disengagement of the lock nut could cause damage to the flap system.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect flap screw jack tracks 2 and 3 for correct locking feature of lock washer against the dome nut, ensuring the cup lock washer P/N MS9952-08 is tapped into groove of lock nut P/N 24156-1. Lubricate the aft end bearing P/N AD50991 with grease P/N MIL-G-23877 or equivalent.
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 the effective date of this AD
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
DeHavilland Model DHC-7 airplanes serial numbers 3 through 36 with flap screw jacks 2 and 3, part numbers 24020-11, -111, -115 or 24040-11, -111, -115, and lock nuts part number MS9952-08.
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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