Exhibit 12.1



TRANSDIGM HOLDING COMPANY

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(Dollars in Thousands)



|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|-------------------------------------- |  | -------------------------- | ------ | -------------------------- | - | --------------------------------- |  | - | -------------------------------- | - |  | -------------------------- | ------ | -------------------------- |  | - | ------ |  | - | -------
|                                       |  | Predecessor                |        |                            |   |                                   |  |   |                                  |  
|                                       |  | YearEndedSeptember 30,2001 |        | YearEndedSeptember 30,2002 |   | October 1,2002ThroughJuly 22,2003 |  |   | July 23,2003ThroughSept. 30,2003 |   |  | YearEndedSeptember 30,2004 |        | YearEndedSeptember 30,2005
|Earnings:                              |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Total earnings (loss)                  |  | $                          | 14,358 |                            | $ | 30,629                            |  | $ | (69,969                          | ) |  | $                          | (2,788 | )                          |  | $ | 29,610 |  | $ | 53,121 
|Income tax provision (benefit)         |  |                            | 9,386  |                            |   | 16,804                            |  |   | (40,701                          | ) |  |                            | (2,275 | )                          |  |   | 16,433 |  |   | 32,999 
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Pre Tax Earnings (loss)                |  |                            | 23,744 |                            |   | 47,433                            |  |   | (110,670                         | ) |  |                            | (5,063 | )                          |  |   | 46,043 |  |   | 86,120 
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Fixed charges:                         |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Interest charges                       |  |                            | 31,926 |                            |   | 36,538                            |  |   | 28,224                           |   |  |                            | 9,567  |                            |  |   | 48,936 |  |   | 51,460 
|Interest factor of operating rents     |  |                            | 365    |                            |   | 419                               |  |   | 408                              |   |  |                            | 163    |                            |  |   | 455    |  |   | 635    
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Total fixed charges                    |  |                            | 32,291 |                            |   | 36,957                            |  |   | 28,632                           |   |  |                            | 9,730  |                            |  |   | 49,391 |  |   | 52,095 
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Earnings as adjusted                   |  | $                          | 56,035 |                            | $ | 84,390                            |  | $ | (82,038                          | ) |  | $                          | 4,667  |                            |  | $ | 95,434 |  | $ | 138,215
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        
|Ratio of earnings to fixed charges (1) |  |                            | 1.7    |                            |   | 2.3                               |  |   |                                 |   |  |                            |       |                            |  |   | 1.9    |  |   | 2.7    
|                                       |  |                            |        |                            |   |                                   |  |   |                                  |   |  |                            |        |                            |  |   |        |  |   |        



|(1) | For purposes of computing the ratio of earnings to fixed charges, earnings consist of earnings before income taxes plus fixed charges. Fixed charges consist of interest expense,
amortization of debt issuance costs and the portion (approximately 33%) of rental expense that management believes is representative of the interest component of rental expense. Earnings were insufficient by $110,670 and $5,063 to cover fixed
charges for the period October 1, 2002 through July 22, 2003 and the period July 23, 2003 through September 30, 2003, respectively.
|--- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------