Joinder Agreement, dated as of December 16, 2008



 Exhibit 10.3 
 JOINDER AGREEMENT 
 THIS JOINDER AGREEMENT (this “Agreement”), dated as of
December 16, 2008, is entered into between AIRCRAFT PARTS CORPORATION, a New York corporation (the “New Subsidiary”), and CREDIT SUISSE, as Agent, under that certain Credit Agreement, dated as of June 23, 2006 (as the same
may be amended, supplemented or otherwise modified from time to time, the “Credit Agreement”), among TransDigm Inc., a Delaware corporation (the “Borrower”), TransDigm Group Incorporated, a Delaware corporation, the
Subsidiaries of the Borrower from time to time party thereto, the Lenders from time to time party thereto and the Agent, as amended by (i) that certain Amendment No. 1, Consent and Agreement dated as of January 25, 2007 and
(ii) that certain Assumption Agreement dated as of February 7, 2007. All capitalized terms used herein and not otherwise defined shall have the meanings set forth in the Credit Agreement. 
 The New Subsidiary and the Agent, for the benefit of the Lenders, hereby agree as follows: 
 1. The New Subsidiary hereby acknowledges, agrees and confirms that, by its execution of this Agreement, the New Subsidiary will be deemed to be a Loan
Party under the Credit Agreement and a Loan Guarantor for all purposes of the Credit Agreement and shall have all of the obligations of a Loan Party and a Loan Guarantor thereunder as if it had executed the Credit Agreement. The New Subsidiary
hereby ratifies, as of the date hereof, and agrees to be bound by, all of the terms, provisions and conditions contained in the Credit Agreement, including without limitation (a) all of the representations and warranties of the Loan Parties set
forth in Article III of the Credit Agreement (to the extent made or deemed made on or after the effective date hereof), (b) all of the covenants set forth in Articles V and VI of the Credit Agreement and (c) all of the guaranty obligations
set forth in the Guarantee and Collateral Agreement. Without limiting the generality of the foregoing terms of this paragraph 1, the New Subsidiary, subject to the limitations set forth in the Guarantee and Collateral Agreement, hereby absolutely
and unconditionally guarantees, jointly and severally with the other Loan Guarantors, to the Agent and the Lenders, the prompt payment of the Secured Obligations in full when due (whether at stated maturity, upon acceleration or otherwise) to the
extent of and in accordance with the Guarantee and Collateral Agreement. 
 2. If required, the New Subsidiary is, simultaneously with the
execution of this Agreement, executing and delivering such Collateral Documents (and such other documents and instruments) as requested by the Agent in accordance with the Credit Agreement, except for items listed on Schedule I hereto which will be
executed and delivered as soon as practical. 
 3. The New Subsidiary hereby waives acceptance by the Agent and the Lenders of the guaranty
by the New Subsidiary upon the execution of this Agreement by the New Subsidiary. 







 4. This Agreement may be executed in any number of counterparts, each of which when so executed and
delivered shall be an original, but all of which shall constitute one and the same instrument. 
 5. THIS AGREEMENT AND THE RIGHTS AND
OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK. 
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 IN WITNESS WHEREOF, the New Subsidiary has caused this Agreement to be duly executed by their respective
authorized officer, and the Agent, for the benefit of the Lenders, has caused the same to be accepted by its authorized officer, as of the day and year first above written. 
  

			
	AIRCRAFT PARTS CORPORATION
		
	By	 	 /s/ Gregory Rufus

	Name:	 	Gregory Rufus
	Title:	 	Secretary










			
	 Acknowledged and accepted:

	
	 CREDIT SUISSE, CAYMAN ISLANDS
 BRANCH, as Agent

		
	 by
	 	 /s/ Robert Hetu

	 Name:
	 	Robert Hetu
	 Title:
	 	Managing Director
		
	 by
	 	 /s/ Christopher Reo Day

	 Name:
	 	Christopher Reo Day
	 Title:
	 	Associate









 SCHEDULE I 
 ITEMS TO BE EXECUTED AND DELIVERED 
  

	 	1.	The stock certificates representing the Equity Interests described immediately below accompanied by stock powers duly executed in blank: 

  

									
	 Issuer
	 	 Number of
 Certificate
	 	 Registered
 Owner
	 	 Number and
 Class of
 Equity Interests

	 	 Percentage
 of Equity
 Interests

	 Aircraft Parts
 Corporation
	 	15	 	TransDigm Inc.	 	5,000 shares of common stock	 	100%

  

	 	2.	Certain documents which pertain to the property listed on Schedule I to Supplement No. 6 to the Guarantee and Collateral Agreement may be delivered pending the outcome of the
appraisal of such property.