Avionic Instruments S-4 Registration of securities issued in business combination transactions

Exhibit 12.1

TRANSDIGM GROUP INCORPORATED

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(Dollars in Thousands)

	Fiscal Years Ended September 30,										Thirteen Week Period Ended
	2009		2008		2007		2006		2005		Jan. 2, 2010		Dec. 27, 2008
Earnings:
Total earnings	$	162,902	$	133,126	$	88,645	$	25,117	$	34,687	$	30,758	$	39,599
Income tax provision		88,100		73,476		53,426		16,318		22,627		17,180		21,307
Pre Tax Earnings		251,002		206,602		142,071		41,435		57,314		47,938		60,906
Fixed charges:
Interest charges		84,398		92,677		91,767		76,732		80,266		28,515		21,982
Interest factor of operating rents (1)		1,095		1,052		931		698		635		317		257
Total fixed charges		85,493		93,729		92,698		77,430		80,901		28,832		22,239
Earnings as adjusted	$	336,495	$	300,331	$	234,769	$	118,865	$	138,215	$	76,770	$	83,145
Ratio of earnings to fixed charges		3.9		3.2		2.5		1.5		1.7		2.7		3.7

(1) For purposes of computing the ratio of earnings to fixed charges, earnings consist of earnings before income taxes plus fixed charges. Fixed charges consists of interest expense, amortization of debt issue costs and the portion of rental expense that management believes is representative of the interest component of rental expense.