Exhibit 10.1

SUPPLEMENT NO. 4 dated as of September 10, 2007, to the Guarantee and Collateral
Agreement dated as of June 23, 2006  (the “Guarantee and Collateral Agreement”),
among TRANSDIGM INC., a Delaware corporation (the “Borrower”), TRANSDIGM GROUP
INCORPORATED, a Delaware corporation (“Holdings”), each subsidiary of the
Borrower listed on Schedule I thereto (each such subsidiary individually a
“Subsidiary Guarantor” and collectively, the “Subsidiary Guarantors”; the
Subsidiary Guarantors, Holdings and the Borrower are referred to collectively
herein as the “Grantors”) and CREDIT SUISSE as administrative agent and
collateral agent (in such capacity, the “Agent”) for the Secured Parties (as
defined herein).

A.  Reference is made to the Credit Agreement dated as of June 23, 2006  (as
amended, supplemented or otherwise modified from time to time, the “Credit
Agreement”), among the Borrower, Holdings, each subsidiary of the Borrower from
time to time party thereto, the lenders named therein (the “Lenders”), and
Credit Suisse, as administrative agent and collateral agent (in such capacity,
the “Agent”) for the Lenders.

B.  Capitalized terms used herein and not otherwise defined herein shall have
the meanings assigned to such terms in the Credit Agreement or the Guarantee and
Collateral Agreement referred to therein, as applicable.

C.  The Grantors have entered into the Guarantee and Collateral Agreement in
order to induce the Lenders to make Loans and the Issuing Bank to issue Letters
of Credit.  Section 7.16 of the Guarantee and Collateral Agreement provides that
additional Domestic Subsidiaries of the Loan Parties may become Subsidiary
Guarantors and Grantors under the Guarantee and Collateral Agreement by
execution and delivery of an instrument in the form of this Supplement.  The
undersigned Subsidiary (the “New Subsidiary”) is executing this Supplement in
accordance with the requirements of the Credit Agreement to become a Subsidiary
Guarantor and a Grantor under the Guarantee and Collateral Agreement in order to
induce the Lenders to make additional Loans and the Issuing Bank to issue
additional Letters of Credit and as consideration for Loans previously made and
Letters of Credit previously issued.

Accordingly, the Agent and the New Subsidiary agree as follows:

SECTION 1.  In accordance with Section 7.16 of the Guarantee and Collateral
Agreement, the New Subsidiary by its signature below becomes a Grantor and
Subsidiary Guarantor under the Guarantee and Collateral Agreement with the same
force and effect as if originally named therein as a Grantor and Subsidiary
Guarantor and the New Subsidiary hereby (a) agrees to all the terms and
provisions of the Guarantee and Collateral Agreement applicable to it as a
Grantor and Subsidiary Guarantor thereunder and (b) represents and warrants that
the representations and warranties made by it as a Grantor and Subsidiary
Guarantor thereunder are true and correct in all material respects on and as of
the date hereof.  In furtherance of the foregoing, the New Subsidiary, as
security for the payment and performance in full of the Secured Obligations (as
defined in the Guarantee and Collateral Agreement), does hereby create and grant
to the Agent, its successors and assigns, for the benefit of the Secured
Parties, their successors and assigns, a security interest in and lien on all of
the New Subsidiary’s right, title and

--------------------------------------------------------------------------------

interest in and to the Collateral (as defined in the Guarantee and Collateral
Agreement) of the New Subsidiary.  Each reference to a “Grantor” or a
“Subsidiary Guarantor” in the Guarantee and Collateral Agreement shall be deemed
to include the New Subsidiary.  The Guarantee and Collateral Agreement is hereby
incorporated herein by reference.

SECTION 2.  The New Subsidiary represents and warrants to the Agent and the
other Secured Parties that this Supplement has been duly authorized, executed
and delivered by it and constitutes its legal, valid and binding obligation,
enforceable against it in accordance with its terms.

SECTION 3.  This Supplement may be executed in counterparts (and by different
parties hereto on different counterparts), each of which shall constitute an
original, but all of which when taken together shall constitute a single
contract. This Supplement shall become effective when the Agent shall have
received counterparts of this Supplement that, when taken together, bear the
signatures of the New Subsidiary and the Agent.  Delivery of an executed
signature page to this Supplement by facsimile transmission shall be as
effective as delivery of a manually signed counterpart of this Supplement.

SECTION 4.  The New Subsidiary hereby represents and warrants that (a) set forth
on Schedule I attached hereto is a true and correct schedule of the location of
any and all Collateral of the New Subsidiary and (b) set forth under its
signature hereto, is the true and correct legal name of the New Subsidiary, its
jurisdiction of formation and the location of its chief executive office.

SECTION 5.  Except as expressly supplemented hereby, the Guarantee and
Collateral Agreement shall remain in full force and effect.

SECTION 6.  THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE
WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 7.  In case any one or more of the provisions contained in this
Supplement should be held invalid, illegal or unenforceable in any respect, the
validity, legality and enforceability of the remaining provisions contained
herein and in the Guarantee and Collateral Agreement shall not in any way be
affected or impaired thereby (it being understood that the invalidity of a
particular provision in a particular jurisdiction shall not in and of itself
affect the validity of such provision in any other jurisdiction). The parties
hereto shall endeavor in good-faith negotiations to replace the invalid, illegal
or unenforceable provisions with valid provisions the economic effect of which
comes as close as possible to that of the invalid, illegal or unenforceable
provisions.

SECTION 8.  All communications and notices hereunder shall be in writing and
given as provided in Section 7.01 of the Guarantee and Collateral Agreement. All
communications and notices hereunder to the New Subsidiary shall be given to it
at the address set forth under its signature below.

2

--------------------------------------------------------------------------------

SECTION 9.  The New Subsidiary agrees to reimburse the Agent for its reasonable
out-of-pocket expenses in connection with this Supplement, including the
reasonable fees, other charges and disbursements of counsel for the Agent.

[Signature pages follow]

3

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the New Subsidiary and the Agent have duly executed this
Supplement to the Guarantee and Collateral Agreement as of the day and year
first above written.

 

BRUCE AEROSPACE INC.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

By

 

/s/ GREGORY RUFUS

 

 

 

 

Name:

 

Gregory Rufus

 

 

 

 

Title:

 

Treasurer and Secretary

 

 

 

 

 

 

 

 

 

 

 

Legal Name: Bruce Aerospace Inc.

 

 

 

 

 

 

 

 

 

 

 

Jurisdiction

 

 

 

 

of Formation: Delaware

 

 

 

 

 

 

 

 

 

 

 

Location of Chief

 

 

 

 

Executive Office:

 

 

 

 

101 Evans Avenue

 

 

 

 

Dayton, Nevada 89403-1700

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BRUCE INDUSTRIES, INC.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

By

 

/s/ GREGORY RUFUS

 

 

 

 

Name:

 

Gregory Rufus

 

 

 

 

Title:

 

Treasurer and Secretary

 

 

 

 

 

 

 

 

 

 

 

Legal Name: Bruce Industries, Inc.

 

 

 

 

 

 

 

 

 

 

 

Jurisdiction

 

 

 

 

of Formation: Colorado

 

 

 

 

 

 

 

 

 

 

 

Location of Chief

 

 

 

 

Executive Office:

 

 

 

 

101 Evans Avenue

 

 

 

 

Dayton, Nevada 89403-1700

 

4

--------------------------------------------------------------------------------

 

 

 

CREDIT SUISSE, as Agent

 

 

 

 

 

 

 

by

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Name:

 

 

 

 

 

 

 

 

Title:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

by

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Name:

 

 

 

 

 

 

 

 

Title:

 

 

 

5

--------------------------------------------------------------------------------