| Summary of segment reporting information | 
        
   
   
   
   
   |   | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   |   | 
     | 
   Nine Months Ended | 
     | 
     | 
   Three Months Ended | 
     | 
    
   
   | (Dollars in thousands) | 
     | 
   September 29, 2012 | 
     | 
     | 
   October 1, 2011 | 
     | 
     | 
   September 29, 2012 | 
     | 
     | 
   October 1, 2011 | 
     | 
    
   
   
   
   | 
    Sales 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   190,212 | 
     | 
     | 
   $ | 
   155,650 | 
     | 
     | 
   $ | 
   65,788 | 
     | 
     | 
   $ | 
   53,509 | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   8,814 | 
     | 
     | 
     | 
   11,357 | 
     | 
     | 
     | 
   3,111 | 
     | 
     | 
     | 
   2,895 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Total Sales 
    | 
     | 
   $ | 
   199,026 | 
     | 
     | 
   $ | 
   167,007 | 
     | 
     | 
   $ | 
   68,899 | 
     | 
     | 
   $ | 
   56,404 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Operating Profit (Loss) and Margins 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   33,358 | 
     | 
     | 
   $ | 
   28,223 | 
     | 
     | 
   $ | 
   10,577 | 
     | 
     | 
   $ | 
   9,897 | 
     | 
    
   
   |   | 
     | 
     | 
   17.5 | 
   %  | 
     | 
     | 
   18.1 | 
   %  | 
     | 
     | 
   16.1 | 
   %  | 
     | 
     | 
   18.5 | 
   %  | 
    
   
   |   | 
     | 
     | 
     | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   (3,525 | 
   )  | 
     | 
     | 
   (1,360 | 
   )  | 
     | 
     | 
   (1,132 | 
   )  | 
     | 
     | 
   (832 | 
   )  | 
    
   
   |   | 
     | 
     | 
   (40.0 | 
   )%  | 
     | 
     | 
   (12.0 | 
   )%  | 
     | 
     | 
   (36.4 | 
   )%  | 
     | 
     | 
   (28.7 | 
   )%  | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Total Operating Profit 
    | 
     | 
     | 
   29,833 | 
     | 
     | 
     | 
   26,863 | 
     | 
     | 
     | 
   9,445 | 
     | 
     | 
     | 
   9,065 | 
     | 
    
   
   |   | 
     | 
     | 
   15.0 | 
   %  | 
     | 
     | 
   16.1 | 
   %  | 
     | 
     | 
   13.7 | 
   %  | 
     | 
     | 
   16.1 | 
   %  | 
    
   
   |   | 
     | 
     | 
     | 
     | 
    
   
   | 
    Deductions from Operating Profit 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Interest Expense 
    | 
     | 
     | 
   803 | 
     | 
     | 
     | 
   1,461 | 
     | 
     | 
     | 
   274 | 
     | 
     | 
     | 
   390 | 
     | 
    
   
   | 
    Corporate Expenses and Other 
    | 
     | 
     | 
   5,137 | 
     | 
     | 
     | 
   3,565 | 
     | 
     | 
     | 
   1,790 | 
     | 
     | 
     | 
   1,170 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Income Before Income Taxes 
    | 
     | 
   $ | 
   23,893 | 
     | 
     | 
   $ | 
   21,837 | 
     | 
     | 
   $ | 
   7,381 | 
     | 
     | 
   $ | 
   7,505 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
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     | 
   
      
    | 
   
      
    | 
     | 
    
   
    
   
   
   
   
   
   |   | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | (In thousands) | 
     | 
   September 29, 2012 | 
     | 
     | 
   
December 31, 2011
 | 
     | 
    
   
   
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   173,261 | 
     | 
     | 
   $ | 
   136,930 | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   18,349 | 
     | 
     | 
     | 
   20,020 | 
     | 
    
   
   | 
    Corporate 
    | 
     | 
     | 
   15,788 | 
     | 
     | 
     | 
   17,955 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Total Assets 
    | 
     | 
   $ | 
   207,398 | 
     | 
     | 
   $ | 
   174,905 | 
     | 
    
   
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