Sec Form 4 Filing - SMALL ROBERT J @ TransDigm Group INC - 2020-10-19

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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

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1. Name and Address of Reporting Person SMALL ROBERT J 2. Issuer Name and Ticker or Trading Symbol TransDigm Group INC [ TDG] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O BERKSHIRE PARTNERS, 200 CLARENDON STREET, 35TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 10/19/2020 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 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 Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 10/19/2020 A 76 A $ 491.32 ( 1 ) 31,024 D Common Stock 2,466,278 I ( 2 ) By Berkshire Entities Common Stock 165,688 I ( 3 ) By Stockbridge Partners LLC Common Stock 20,301 I ( 4 ) By Family Trust Common Stock 50,000 I ( 5 ) By Trust

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SMALL ROBERT J C/O BERKSHIRE PARTNERS 200 CLARENDON STREET, 35TH FLOOR BOSTON, MA02116 X Signatures Halle Fine Terrion as attorney-in-fact for Robert Small 10/20/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Receipt of stock in lieu of payment of semi-annual director fee, based on fair market value in accordance with the Director Share Plan. ( 2 )Represents shares held directly or indirectly by Berkshire Fund VIII, L.P. ("VIII"), Berkshire Fund VIII-A, L.P. ("VIII-A"), Berkshire Fund IX, L.P. ("IX"), Berkshire Fund IX-A, L.P. ("IX-A"), Berkshire Investors III LLC ("Investors III"), Berkshire Investors IV LLC ("Investors IV"), Stockbridge Fund, L.P. ("SF") and Stockbridge Absolute Return Fund, L.P. ("SARF") (collectively, the "Berkshire Entities"). Berkshire Partners Holdings LLC ("BPH") is the general partner of BPSP, L.P. ("BPSP"), which is the managing member of each of Berkshire Partners, LLC, the registered investment adviser to VIII, VIII-A, IX, IX-A, Investors III and Investors IV ("BP"), and SP, the registered investment adviser to SF and SARF. Eighth Berkshire Associates LLC ("8BA") is the general partner of each of VIII and VII-A. Ninth Berkshire Associates LLC ("9BA") is the general partner of each of IX and IX-A. Stockbridge Associates LLC ("SA") is the general partner of each of SF and SARF. ( 3 )Represents shares held by SP on behalf of a managed account over which it has shared voting and sole dispositive power. ( 4 )Represents shares of Common Stock beneficially owned by certain family trusts. The Reporting Person is a trustee and the Reporting Person's immediate family members are beneficiaries of such family trusts ( 5 )Represents shares of Common Stock beneficially owned by a trust. The Reporting Person is a trustee and the Reporting Person's immediate family members are beneficiaries of such trust.

Remarks: Indirect ownership of shares held by the Berkshire Entities and SP is included because the Reporting Person is a managing member of SP and of BPH, BPSP, BP, SP, 8BA, 9BA, SA, Investors III and Investors IV (see footnotes 1 and 2). As such, the Reporting Person may be deemed to share voting and dispositive power with respect to the shares of the Issuer's stock held by the Berkshire Entities and SP. However, the Reporting Person disclaims beneficial ownership of such shares, expect to the extent, if any, of his pecuniary interest therein, and inclusion of the shares in this report shall not be deemed an admission of beneficial ownership of the securities for purposes of Section 16 or any other purpose.

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 4(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).

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