Joinder Agreement, dated as of September 3, 2010



 Exhibit 10.4 

EXECUTION VERSION 

JOINDER AGREEMENT 

THIS JOINDER AGREEMENT (this “Agreement”), dated as of September 3, 2010, is entered into between SEMCO
INSTRUMENTS, INC., a Delaware corporation (the “New Subsidiary”), and CREDIT SUISSE AG, 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. Delivery of an executed signature page to this Agreement by facsimile transmission or electronic transmission (including in pdf format) shall be as
effective as delivery of a manually signed counterpart of this Agreement. 
 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. 

[Remainder of page intentionally left blank] 
  


 2 








 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. 

 

							
	 SEMCO INSTRUMENTS, INC.

			
		 	by	 	 /s/ Gregory Rufus

		 		 	Name:	 	Gregory Rufus
		 		 	Title:	 	Secretary and Treasurer


 Semco
Instruments, Inc. Joinder Agreement 








							
	 Acknowledged and accepted:

	
	 CREDIT SUISSE AG, CAYMAN ISLANDS BRANCH, as Agent

			
		 	by	 	 /s/ Ari Bruger

		 		 	Name:	 	Ari Bruger
		 		 	Title:	 	Vice President
			
		 	by	 	 /s/ Kevin Buddhdew

		 		 	Name:	 	Kevin Buddhdew
		 		 	Title:	 	Associate


 Semco Instruments, Inc.
Joinder Agreement 
  







 SCHEDULE I 

ITEMS TO BE EXECUTED AND DELIVERED 

None. 
  

 Schedule I-1