- Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^*

Leary John F

2. Date of Event Requiring Statement (MM/DD/YYYY) 5/31/2012

3. Issuer Name and Ticker or Trading Symbol

TransDigm Group INC [TDG]

(Last) (First) (Middle)

C/O HARTWELL CORPORATION, 900 RICHFIELD RD

4. Relationship of Reporting Person(s) to Issuer (Check all applicable)

_____ Director _____ 10% Owner
___ X ___ Officer (give title below) _____ Other (specify below)
Executive Vice President /

(Street)

PLACENTIA, CA 92870

(City) (State) (Zip)

5. If Amendment, Date Original Filed (MM/DD/YYYY)

6. Individual or Joint/Group Filing (Check Applicable Line)

_ X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

*Table II - Derivative Securities Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivate Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Stock Option	9/30/2004	8/5/2013	Common Stock	8664	$6.68	D
Stock Option	8/5/2003	8/5/2013	Common Stock	38896	$6.68	D
Stock Option	9/28/2005	8/5/2013	Common Stock	748	$13.37	D
Stock Option	9/30/2009 ⁽¹⁾	11/17/2018	Common Stock	60000	$27.08	D
Stock Option	9/30/2011 ⁽²⁾	4/27/2021	Common Stock	12000	$80.80	D
Stock Option	9/30/2012 ⁽³⁾	11/14/2021	Common Stock	45500	$97.42	D

Explanation of Responses:
( 1)	Vest based on the achievement of annual and cumulative per share operating performance targets between fiscal 2009 and fiscal 2013.
( 2)	Vest based on the achievement of annual per share operating performance targets between fiscal 2014 and fiscal 2015.
( 3)	Vest based on the achievement of annual and cumulative per share operating performance targets between fiscal 2012 and fiscal 2016.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
Leary John F C/O HARTWELL CORPORATION 900 RICHFIELD RD PLACENTIA, CA 92870			Executive Vice President

Signatures
Halle Fine Terrion as attorney in fact for John Leary		6/5/2012
^** Signature of Reporting Person		Date

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.