Cessna parent company Textron Aviation issued an update to service letters SEL-57-08 and SEL-57-09 concerning inspection of carry through spars on Cessna model 177 and 210 aircraft. 

The update adds a new step to the inspection process for eddy current inspection of the kick area on the lower surface of the lower spar cap as well as providing additional clarification regarding qualification for inspection technicians.  

The revision also adds information regarding the use of zinc chromate or epoxy primer on the spar to prevent further corrosion. 

Download 210 Service Letter

Download 177 Service Letter