TransDigm Group INC — Director's Dealing 2010

May 18, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: TransDigm Group INC (TDG)
CIK: 0001260221
Period of Report: 2010-05-14

Reporting Person: SMALL ROBERT J (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-05-14	Common Stock	P	15000	$55.82	Acquired	4228562	Indirect
2010-05-17	Common Stock	P	11000	$55.96	Acquired	4239562	Indirect

Footnotes

F1: Represents shares acquired by one of the Berkshire Entities (as defined below), a passive investment fund (the "Fund"), consistent with its investment objective of achieving capital appreciation by investing primarily in marketable securities. This Form 4 has been filed because the Reporting Person is a director of the Issuer and a managing member of the general partner of the Fund. As such, the Reporting Person may be deemed to have a shared voting and/or dispositive power over the shares held by the Fund. However, the Reporting Person disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.

F2: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $55.62 to $56.00. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F3: Owned by Berkshire Fund VII, L.P., Berkshire Fund VII-A, L.P., Berkshire Investors LLC, Berkshire Investors III LLC and Stockbridge Fund, L.P. (collectively, the "Berkshire Entities"). Seventh Berkshire Associates LLC is the general partner of each of Berkshire Fund VII, L.P. and Berkshire Fund VII-A, L.P. Stockbridge Associates LLC is the general partner of Stockbridge Fund, L.P. The Reporting Person is a managing member of each of Seventh Berkshire Associates LLC, Stockbridge Associates LLC, Berkshire Investors LLC and Berkshire Investors III LLC. As such, the Reporting Person may be deemed to have a shared voting and/or dispositive power over the shares held by such entities. However, the Reporting Person disclaims beneficial ownership of these shares, except to the extent of his pecuniary interest therein.

F4: The Reporting Person may also be deemed to indirectly beneficially own 103,500 shares of Common Stock held by Stockbridge Partners LLC on behalf of a managed account over which it has shared voting and sole dispositive power. The Reporting Person is a managing member of Stockbridge Partners LLC. As such, the Reporting Person may be deemed to have a shared voting and/or dispositive power over these shares. However, the Reporting Person disclaims beneficial ownership of these shares, except to the extent of his pecuniary interest therein.

F5: Mr. Small also directly beneficially owns 5,000 shares of Common Stock.

F6: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $55.85 to $56.00. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.