AD 77-20-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Pilatus Aircraft Limited | PC-6 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6-H1 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6-H2 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/350 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/350-H1 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/350-H2 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/A | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/A-H1 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/A-H2 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
| aircraft | Pilatus Aircraft Limited | PC-6/B-H2 | Airworthiness Directives; Pilatus Model PC-6 Airplanes (all variants); Fairchild Hiller Model PC-6 Airplanes (all variants) |
Unsafe Condition
Hazardous degree of corrosion developing inside the wing struts and on the wing strut attachment brackets for certain Pilatus and Fairchild Hiller PC-6 airplanes.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually inspect wing struts and attachment brackets for corrosion per specified service bulletins. Remove light corrosion and apply anticorrosive treatment, or replace struts/brackets if corrosion exceeds limits. Inspections must be repeated at intervals not exceeding 100 hours time in service until conditions in paragraph (c) are met.
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 (November 3, 1977), unless already accomplished within the last 75 hours time in service. Thereafter, inspections must be conducted at intervals not to exceed 100 hours time in service.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pilatus Aircraft Ltd. Model PC-6 airplanes (all variants) up to S/N 724 and Fairchild Hiller Model PC-6 airplanes (all variants) with S/N 2001 through 2047. Additionally, Pilatus Model PC-6 S/N 338 through 701 require inspections on wing strut attachment brackets.
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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