More than 100 Cessna Corvalis 400 TTs are now equipped with TKS ice protection as a factory option or retrofit. Now, owners of Corvalis 300/350s can have the system installed. CAV Aerospace, which holds the patent for the "weeping wing" TKS system, announced last week it has received an amended FAA Supplemental Type Certificate to retrofit existing Corvalis 300s and 350s. The approval came after flight testing in an early model Corvalis 350. With the approval, the full line of Corvalis singles is now eligible for the TKS retrofit.