error: Helper Module in a subdirectory - RESTful route used

I am using a namespace

     map.namespace :admin do |admin|
      admin.resources :repairs
     end

which puts my repairs_controller.rb and my repairs views into admin
subdirectory

when I use an Helper method repaired_tables(@repair) in my
views/admin/repairs/show.html.erb

I get an error "undefined method `repaired_tables' "

I tried to put my repairs_helper inside a subdirectory too, .. no change

Where shoudl I put it ? anything to add ?

thanks for your lights

kad