Joinder Agreement, dated as of December 9, 2011



 Exhibit 10.1 
 JOINDER AGREEMENT 
 THIS JOINDER AGREEMENT (this “Agreement”),
dated as of December 9, 2011, is entered into between HARCO LABORATORIES, INCORPORATED, a Connecticut corporation (the “New Subsidiary”) and CREDIT SUISSE AG, as administrative agent and collateral agent (in such capacities,
the “Agent”), under that certain Credit Agreement, dated as of December 6, 2010, as amended by Amendment No. 1 as of March 25, 2011 (as the same may be further 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. 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 Subsidiary 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 Guarantors, to the Agent and the Lenders, the prompt payment of the Additional Obligations in full when due (whether at stated maturity, upon acceleration or
otherwise) to the extent of and in accordance with 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 reasonably requested by the Agent in accordance with the Credit Agreement. 

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. 







 IN WITNESS WHEREOF, the New Subsidiary has caused this Agreement to be duly executed by its
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. 

 

			
	HARCO LABORATORIES, INCORPORATED
		
	    by	 	 /s/ Gregory Rufus

		 	Name: Gregory Rufus
		 	Title: Treasurer and Secretary
		 	Address:
		 	Legal Name:
		 	 Jurisdiction of

    Formation:

		 	 Location of Chief

    Executive Office:



 Acknowedged and accepted: 

 

			
	CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH, as Agent
		
	    by	 	 /s/ Robert Hetu

		 	Name: Robert Hetu
		 	Title: Managing Director
		
	    by	 	 /s/ Kevin Buddhdew

		 	Name: Kevin Buddhdew
		 	Title: Associate