| Summary of segment reporting information | 
        
   
   
   
   
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     | 
     | 
     | 
     | 
    
   
   |   | 
     | 
   Six Months Ended | 
     | 
     | 
   Three Months Ended | 
     | 
    
   
   | (Dollars in thousands) | 
     | 
   June 30, 2012 | 
     | 
     | 
   July 2, 2011 | 
     | 
     | 
   June 30, 2012 | 
     | 
     | 
   July 2, 2011 | 
     | 
    
   
   
   
   |   | 
     | 
     | 
     | 
     | 
    
   
   | 
    Sales 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   124,424 | 
     | 
     | 
   $ | 
   102,141 | 
     | 
     | 
   $ | 
   62,423 | 
     | 
     | 
   $ | 
   51,942 | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   5,703 | 
     | 
     | 
     | 
   8,462 | 
     | 
     | 
     | 
   2,566 | 
     | 
     | 
     | 
   3,533 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Sales 
    | 
     | 
   $ | 
   130,127 | 
     | 
     | 
   $ | 
   110,603 | 
     | 
     | 
   $ | 
   64,989 | 
     | 
     | 
   $ | 
   55,475 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   |   | 
     | 
     | 
     | 
     | 
    
   
   | 
    Operating Profit (Loss) and Margins 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   22,781 | 
     | 
     | 
   $ | 
   18,330 | 
     | 
     | 
   $ | 
   10,903 | 
     | 
     | 
   $ | 
   9,011 | 
     | 
    
   
   |   | 
     | 
     | 
   18.3 | 
   %  | 
     | 
     | 
   17.9 | 
   %  | 
     | 
     | 
   17.5 | 
   %  | 
     | 
     | 
   17.3 | 
   %  | 
    
   
   |   | 
     | 
     | 
     | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   (2,393 | 
   )  | 
     | 
     | 
   (528 | 
   )  | 
     | 
     | 
   (1,318 | 
   )  | 
     | 
     | 
   (545 | 
   )  | 
    
   
   |   | 
     | 
     | 
   (42.0 | 
   )%  | 
     | 
     | 
   (6.2 | 
   )%  | 
     | 
     | 
   (51.4 | 
   )%  | 
     | 
     | 
   (15.4 | 
   )%  | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Total Operating Profit 
    | 
     | 
     | 
   20,388 | 
     | 
     | 
     | 
   17,802 | 
     | 
     | 
     | 
   9,585 | 
     | 
     | 
     | 
   8,466 | 
     | 
    
   
   |   | 
     | 
     | 
   15.7 | 
   %  | 
     | 
     | 
   16.1 | 
   %  | 
     | 
     | 
   14.7 | 
   %  | 
     | 
     | 
   15.3 | 
   %  | 
    
   
   | 
    Deductions from Operating Profit 
    | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | 
    Interest Expense 
    | 
     | 
     | 
   529 | 
     | 
     | 
     | 
   1,071 | 
     | 
     | 
     | 
   266 | 
     | 
     | 
     | 
   534 | 
     | 
    
   
   | 
    Corporate Expenses and Other 
    | 
     | 
     | 
   3,347 | 
     | 
     | 
     | 
   2,399 | 
     | 
     | 
     | 
   1,809 | 
     | 
     | 
     | 
   1,224 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Income Before Income Taxes 
    | 
     | 
   $ | 
   16,512 | 
     | 
     | 
   $ | 
   14,332 | 
     | 
     | 
   $ | 
   7,510 | 
     | 
     | 
   $ | 
   6,708 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
     | 
     | 
   
      
    | 
   
      
    | 
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     | 
   
      
    | 
   
      
    | 
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     | 
   
      
    | 
   
      
    | 
     | 
    
   
    
   
   
   
   
   
   |   | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
     | 
    
   
   | (In thousands) | 
     | 
   June 30, 2012 | 
     | 
     | 
   Dec. 31, 2011 | 
     | 
    
   
   
   
   | 
    Aerospace 
    | 
     | 
   $ | 
   152,736 | 
     | 
     | 
   $ | 
   136,930 | 
     | 
    
   
   | 
    Test Systems 
    | 
     | 
     | 
   18,133 | 
     | 
     | 
     | 
   20,020 | 
     | 
    
   
   | 
    Corporate 
    | 
     | 
     | 
   16,703 | 
     | 
     | 
     | 
   17,955 | 
     | 
    
   
   |   | 
     | 
   
      
    | 
   
      
    | 
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     | 
   
      
    | 
   
      
    | 
     | 
    
   
   | 
    Total Assets 
    | 
     | 
   $ | 
   187,572 | 
     | 
     | 
   $ | 
   174,905 | 
     | 
    
   
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     | 
   
      
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