Ruby on Rails application controller
You can move helper methods to ApplicationHelper and simply include it in Application controller, so your code will look like:

ApplicationController:

class ApplicationController &lt; ActionController::Base
  include ApplicationHelper
  protect_from_forgery with: :exception

  private
    def current_role
        current_role = current_user.nil? ? 'Not logged in' : Role.find(current_user.role_id).name 
    end

    def require_new_operation_permission
      check_permission('representative', 'agent')
    end

    def check_permission(*roles)
      unless roles.include? current_role
        flash[:alert] = "Access denied"
        redirect_back(fallback_location: authenticated_root_path)
      end
    end
end


ApplicationHelper:

module ApplicationHelper
  # Roles detection helpers
  def is_admin?
    current_role == 'admin' ? true : false
  end

  def is_representative?
    current_role == 'representative' ? true : false
  end

  def is_shipper?
    current_role == 'shipper' ? true : false
  end

  def is_agent?
    current_role == 'agent' ? true : false
  end

  def is_pricing_representative?
    current_role == 'pricing_representative' ? true : false
  end

  # Devise helpers
  def resource_name
    :user
  end

  def resource
    @resource ||= User.new
  end

  def resource_class
    User
  end

  def devise_mapping
    @devise_mapping ||= Devise.mappings[:user]
  end


  # Operation helpers
  def is_operation_completed?(operation_id)
    GeneralCargoInfo.find_by(operation_id: operation_id).nil? ? false : true
  end

  # FCL-EXW helpers
  def is_fcl_exw_info_stage_completed?(operation_id)
    FclExwCargoInfo.find_by(operation_id: operation_id).nil? ? false : true
  end

  def is_fcl_exw?(operation_id)
    Operation.find(operation_id).modality == 'FCL - EXW' ? true : false
  end

  def is_fcl_exw_info_requested?(operation_id)
    Operation.find(operation_id).fcl_exw_info_requested
  end

  def is_fcl_exw_info_confirmed?(operation_id)
    Operation.find(operation_id).fcl_exw_info_confirmed
  end

  def is_fcl_exw_quotation_confirmed?(operation_id)
    Operation.find(operation_id).fcl_exw_quotation_confirmed
  end
end