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

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(Print or Type Responses)

1. Name and Address of Reporting Person *   TA ASSOCIATES INC 2. Date of Event Requiring Statement (Month/Day/Year) 03/08/2006 3. Issuer Name and Ticker or Trading Symbol Eagle Test Systems, Inc. [EGLT] (Last) (First) (Middle) 125 HIGH STREET 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) BOSTON, MA 02110 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)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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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
Series A Convertible Preferred Stock	03/08/2006	  (1)	Common Stock	8,590,247	$ (2)	I (3) (4)	See Footnotes 3 & 4
12% Convertible Notes due 2009	03/08/2006	09/30/2009	Common Stock	525,040	$ 0.01 (5)	I (3) (4)	See Footnotes 3 & 4

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
TA ASSOCIATES INC 125 HIGH STREET BOSTON, MA 02110	Â	  X	Â	Â

Signatures

TA Associates Inc. By: Thomas P. Alber, Chief Financial Officer /s/ Thomas P. Alber		03/08/2006
**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)	These securities are preferred stock of the Issuer and do not have an expiration date.
(2)	The shares of Series A Convertible Preferred Stock will convert at a rate of 1-to-2,500 into the number of shares of Common Stock shown in column 3 above.
(3)	The reporting person may be deemed to have an indirect pecuniary interest as the General Partner of TA Associates AP IV L.P., TA Associates SPF L.P. and as the Manager of TA Associates IX LLC, TA Associates SDF LLC and TA Investors LLC. The reporting person disclaims beneficial ownership of such shares because the reporting person's indirect pecuniary interest is subject to indeterminable future events.
(4)	The reporting person is the indirect beneficial owner of the following shares of Common Stock: (i) 6,475,725 shares owned by TA IX L.P.; (ii) 1,828,665 shares owned by TA/Atlantic and Pacific IV L.P.; (iii) 132,555 shares owned by TA Strategic Partners Fund A L.P.; (iv) 23,787 shares owned by TA Strategic Partners Fund B L.P.; (v) 139,805 shares owned by TA Investors LLC; and (vi) 514,750 shares owned by TA Subordinated Debt Fund L.P. TA Associates IX LLC is the General Partner of TA IX L.P. TA Associates SDF LLC is the General Partner of TA Subordinated Debt Fund L.P. TA Associates AP IV L.P. is the General Partner of TA/Atlantic and Pacific IV L.P. TA Associates SPF L.P. is the General Partner of TA Strategic Partners Fund A L.P. and TA Strategic Partners Fund B L.P.
(5)	The 12% Convertible Notes due 2009 are immediately convertible into 12% Notes due 2009 and warrants to purchase Common Stock, which warrants are immediately exercisable for 525,040 shares of Common Stock.

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