FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES 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

OMB APPROVAL OMB Number: 3235-0104 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person *   LEE KEWSONG 2. Date of Event Requiring Statement (Month/Day/Year) 03/14/2006 3. Issuer Name and Ticker or Trading Symbol TransDigm Group INC [TDG] (Last) (First) (Middle) C/O WARBURG PINCUS & CO., 466 LEXINGTON AVENUE 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) NEW YORK, NY 10017 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) 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) Common Stock, par value $0.01 per share 30,601,875 I See Footnotes (1) (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
	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.

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		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)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
LEE KEWSONG C/O WARBURG PINCUS & CO. 466 LEXINGTON AVENUE NEW YORK, NY 10017	  X	Â	Â	Â

Signatures

/s/ Kewsong Lee		03/14/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The stockholder is Warburg Pincus Private Equity VIII, L.P., including two affiliated partnerships ("WP VIII"). Warburg Pincus Partners LLC ("WP Partners LLC"), a subsidiary of Warburg Pincus & Co. ("WP"), is the sole general partner of WP VIII. WP VIII is managed by Warburg Pincus LLC ("WP LLC" and together with WP, WP VIII and WP Partners LLC, the "Warburg Entities"). Kewsong Lee, a director of TransDigm Group Incorporated, a Delaware corporation, is a general partner of WP and a managing director and member of WP LLC. All shares indicated as owned by Kewsong Lee are included because of his affiliation with the Warburg Entities. Kewsong Lee may be deemed to have an indirect pecuniary interest (within the meaning of Rule 16a-1 under the Securities Exchange Act of 1934) in an indeterminate portion of the shares owned by WP VIII. Kewsong Lee disclaims beneficial ownership of all shares held by the Warburg Entities.
(2)	Charles R. Kaye and Joseph P. Landy are Managing General Partners of WP and Managing Members of WP LLC and may be deemed to control the Warburg Entities. Messrs. Kaye and Landy disclaim beneficial ownership of all shares held by the Warburg Entities. The address of the Warburg Entities is 466 Lexington Avenue, New York, New York 10017.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.