Second Supplemental Indenture, dated as of December 9, 2011



 Exhibit 4.1 
 TRANSDIGM INC., 
 TRANSDIGM GROUP INCORPORATED, 

THE GUARANTORS NAMED HEREIN, 
 AND 
 THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., 

as Trustee 
  

 
 SECOND
SUPPLEMENTAL INDENTURE 
 Dated as of December 9, 2011 

to 
 Indenture

 Dated as of December 14, 2010 
 by and among 
 TRANSDIGM INC., 

TRANSDIGM GROUP INCORPORATED, 
 THE GUARANTORS NAMED THEREIN, 
 AND 

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., 
 as Trustee 
  

 
 7.75% Senior
Subordinated Notes due 2018 
 of TransDigm Inc. 







 This SECOND SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”),
dated as of December 9, 2011, by and among Harco Laboratories, Incorporated, a Connecticut corporation (“Harco” or the “Guaranteeing Subsidiary”), TransDigm Inc., a Delaware corporation
(the “Company”), TransDigm Group Incorporated, a Delaware corporation (“TD Group”), Adams Rite Aerospace, Inc., a California corporation (“Adams Rite”), MarathonNorco Aerospace, Inc., a
Delaware corporation (“Marathon”), Champion Aerospace LLC, a Delaware limited liability company (“Champion”), Avionic Instruments LLC, a Delaware limited liability company (“Avionic”), Skurka
Aerospace Inc., a Delaware corporation (“Skurka”), CDA InterCorp LLC, a Florida limited liability company (“CDA”), Aviation Technologies, Inc., a Delaware corporation (“ATI”), Avtech Corporation, a
Washington corporation (“Avtech”), Transicoil LLC, a Delaware limited liability company (“Transicoil”), AeroControlex Group, Inc., a Delaware corporation (“Aerocontrolex”), Malaysian Aerospace
Services, Inc., a Delaware corporation (“Malaysian”), Bruce Aerospace Inc., a Delaware corporation (“Bruce Aerospace”), Bruce Industries, Inc., a Colorado corporation (“Bruce Industries”), CEF
Industries, LLC, a Delaware limited liability company (“CEF”), Aircraft Parts Corporation, a New York corporation (“APC”), Acme Aerospace, Inc., a Delaware corporation (“Acme”), Dukes Aerospace,
Inc., a Delaware corporation (“Dukes”), Semco Instruments, Inc., a Delaware corporation, (“Semco”), Hartwell Corporation, a California corporation (“Hartwell”), McKechnie Aerospace DE, Inc., a
Delaware corporation (“Mckechnie Aerospace DE”), McKechnie Aerospace Holdings, Inc., a Delaware corporation (“McKechnie Aerospace Holdings”), McKechnie Aerospace Investments, Inc., a Delaware corporation
(“McKechnie Aerospace Investments”), McKechnie Aerospace US LLC, a Delaware limited liability company (“McKechnie Aerospace US”), Texas Rotronics, Inc., a Texas corporation (“Rotronics”), Western
Sky Industries, LLC, a Delaware limited liability company (“Western”), Schneller Holdings LLC, a Delaware limited liability company (“Schneller Holdings”), Schneller LLC, a Delaware limited liability company
(“Schneller”) and Schneller International Sales Corp., an Ohio corporation (“Schneller International” and, together with TD Group, Adams Rite, Marathon, Champion, Avionic, Skurka, CDA, ATI, Avtech, Transicoil,
AeroControlex, Malaysian, Bruce Aerospace, Bruce Industries, CEF, APC, Acme, Dukes, Semco, Hartwell, McKechnie Aerospace DE, McKechnie Aerospace Holdings, McKechnie Aerospace Investments, McKechnie Aerospace US, Rotronics, Western, Schneller
Holdings and Schneller, the “Existing Guarantors”), and The Bank of New York Mellon Trust Company, N.A., as trustee (the “Trustee”) under the Indenture referred to below. Capitalized terms used herein and not
otherwise defined shall have the meaning assigned to them in the Indenture. 
 WITNESSETH: 

WHEREAS, the Company and the Existing Guarantors have heretofore executed and delivered to the Trustee an indenture, dated as of
December 14, 2010 (as supplemented by the First Supplemental Indenture thereto, dated as of September 22, 2011, the “Indenture”), providing for the issuance by the Company of 7.75% Senior Subordinated Notes due 2018
(the “Notes”) and the guarantees thereof by each of the Existing Guarantors; 
 WHEREAS, the
Indenture provides that under certain circumstances described therein, newly created or acquired Domestic Restricted Subsidiaries shall execute and deliver to the Trustee a supplemental indenture to the Indenture providing for a senior subordinated
guarantee of payment of the Notes by such Domestic Restricted Subsidiary (the “Guarantee”); 
 WHEREAS,
all things necessary to make this Supplemental Indenture the legal, valid and binding obligation of the Company, the Existing Guarantors and the Guaranteeing Subsidiary have been done; and 

WHEREAS, pursuant to Section 9.01(g) of the Indenture, the Trustee is authorized to execute and deliver this Supplemental
Indenture without the consent of the Holders of the Notes. 
 NOW, THEREFORE, in consideration of the foregoing and for
other good and valuable consideration, the receipt of which is hereby acknowledged, the Guaranteeing Subsidiary covenants and agrees for the equal and ratable benefit of the Holders of the Notes as follows: 

 

	 	1.	CAPITALIZED TERMS. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture. 


 

	 	2.	 GUARANTEE, ETC. The Guaranteeing Subsidiary hereby agrees that from and after the date hereof it shall be a Guarantor under the Indenture and be
bound by the terms thereof applicable to Guarantors and 



  
 -2-










	 	
shall be entitled to all of the rights and subject to all the obligations of a Guarantor thereunder. 

  


	 	3.	RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURE PART OF INDENTURE. The Indenture is in all respects ratified and confirmed and all the terms, conditions and
provisions thereof shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all purposes, and every holder of Notes heretofore or hereafter authenticated and delivered shall be bound hereby.


  

	 	4.	EXECUTION AND DELIVERY. The Guaranteeing Subsidiary agrees that the Guarantee granted by it pursuant to the terms hereof shall remain in full force and effect
notwithstanding any failure to endorse on each Note a notation of such Guarantee. 

  

	 	5.	NO RECOURSE AGAINST OTHERS. No past, present or future director, officer, employee, incorporator, stockholder or agent of the Guaranteeing Subsidiary (or any
successor entity) (other than the Company or the Existing Guarantors), as such, shall have any liability for any obligations of the Company, TD Group, the Guaranteeing Subsidiary or any other Guarantor under the Notes, any Guarantee, the Indenture
or this Supplemental Indenture or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each Holder of the Notes by accepting a Note waives and releases all such liability. The waiver and release are part of the
consideration for issuance of the Notes. 

  

	 	6.	NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE AND THE GUARANTEE GRANTED
HEREUNDER WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY. 


 

	 	7.	COUNTERPART ORIGINALS. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together
represent the same agreement. 

  

	 	8.	EFFECT OF HEADINGS. The Section headings have been inserted for convenience of reference only, are not to be considered part of this Supplemental Indenture and
shall in no way modify or restrict any of the terms or provisions hereof. 

  

	 	9.	THE TRUSTEE. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or for
or in respect of the recitals contained herein, all of which recitals are made solely by the Guaranteeing Subsidiary, the Existing Guarantors and the Company. 


  
 -3-









 IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be
duly executed as of the date hereof. 
  

			
	TRANSDIGM INC.
		
	By:	 	/s/ Gregory Rufus
	 Name:
 Title:
	 	 Gregory Rufus

Executive Vice President and Chief Financial Officer



  

			
	TRANSDIGM GROUP INCORPORATED
		
	By:	 	/s/ Gregory Rufus
	 Name:
 Title:
	 	 Gregory Rufus

Executive Vice President and Chief Financial Officer

	
	 ACME AEROSPACE, INC.

ADAMS RITE AEROSPACE, INC.
 AEROCONTROLEX GROUP,
INC.
 AIRCRAFT PARTS CORPORATION

AVIATION TECHNOLOGIES, INC.
 AVTECH
CORPORATION
 BRUCE AEROSPACE INC.

BRUCE INDUSTRIES, INC.
 DUKES AEROSPACE,
INC.
 HARTWELL CORPORATION
 HARCO
LABORATORIES, INCORPORATED
 MALAYSIAN AEROSPACE SERVICES, INC.
 MARATHONNORCO AEROSPACE, INC.
 MCKECHNIE AEROSPACE DE, INC.

MCKECHNIE AEROSPACE HOLDINGS, INC.

MCKECHNIE AEROSPACE INVESTMENTS, INC.
 MCKECHNIE AEROSPACE US LLC

            By: McKechnie Aerospace DE, Inc., its sole member

SCHNELLER INTERNATIONAL SALES CORP.
 SEMCO
INSTRUMENTS, INC.
 SKURKA AEROSPACE INC.

TEXAS ROTRONICS, INC.

	TRANSICOIL LLC
	            By: Aviation Technologies, Inc., its sole member
	 WESTERN SKY INDUSTRIES, LLC

	             By: McKechnie Aerospace Investments,
Inc.,

                   
 its sole member

		
	By:	 	/s/ Gregory Rufus
	 Name:
 Title:
	 	 Gregory Rufus

Treasurer and Secretary

	
	 AVIONIC INSTRUMENTS LLC
 CDA INTERCORP LLC
 CEF INDUSTRIES, LLC
 CHAMPION AEROSPACE LLC
 SCHNELLER HOLDINGS LLC

SCHNELLER LLC

	          By: Schneller Holdings LLC, its sole member
		
	By:	 	TransDigm Inc., its sole member
		
	By:	 	/s/ Gregory Rufus
	 Name:
 Title:
	 	 Gregory Rufus Executive

Vice President and Chief Financial Officer




  
 -4-









 
			
	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., AS TRUSTEE
		
	By:	 	/s/ Richard Tarnas
	 Name:
 Title:
	 	 R. Tarnas
 Vice
President




  
 -5-