# Airworthiness Directives; Pilatus Aircraft Limited Models B4-PC11, B4-PC11A, and B4-PC11AF Sailplanes
> **Rule** · Final rule. · Published 2005-04-21 · Effective 2005-06-02 · 70 FR 20708
## Document
- **Document number:** 05-7563
- **Category:** airworthiness
- **Manufacturer:** Pilatus
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 70 FR 20708
- **Publication date:** 2005-04-21
- **Effective date:** 2005-06-02
- **FAA docket:** Docket No. FAA-2004-20006
## Abstract

The FAA adopts a new airworthiness directive (AD) for all Pilatus Aircraft Limited (Pilatus) Models B4-PC11, B4-PC11A, and B4- PC11AF sailplanes. This AD requires you to repetitively inspect the control-column support for cracks and, if any cracks are found, replace the control-column support with a new support. This AD results from mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. We are issuing this AD to detect and correct cracks in the control-column support, which could result in failure of the support. This failure could lead to loss of the primary flight control system.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2005/04/21/05-7563/airworthiness-directives-pilatus-aircraft-limited-models-b4-pc11-b4-pc11a-and-b4-pc11af-sailplanes)
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