The FAA doesn't just give out check airman letters or type rating designee authorizations. You have to be able to show a need that can not be filled by the status quo. You have to show you'll be conducting a minimum number of checks a year to have an in house check airman. Same thing for a type rating designee. Just because a 142 center charges a wing and an engine is not a valid reason. It's normally a scheduling issue (not enough FAA inspectors) or not one authorized to issue that type.