Summary
The FAA proposes to adopt a new airworthiness directive (AD) for all Pilatus Aircraft Limited (Pilatus) Models B4-PC11, B4-PC11A, and B4-PC11AF sailplanes. This proposed AD would require 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 proposed AD results from mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. We are issuing this proposed 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.