Exhibit 99.6  FIFTH AMENDMENT TO REIMBURSEMENT,
CREDIT AND SECURITY AGREEMENT  THIS FIFTH AMENDMENT TO
REIMBURSEMENT, CREDIT AND SECURITY AGREEMENT (this Amendment) is made as of
this10TH day of January, 2008, by and between INNOVATIVE SOLUTIONS
AND SUPPORT, LLC (the Borrower) and PNC BANK, NATIONAL ASSOCIATION (the Bank).  RECITALS:  A.The Bank and the Borrower entered into a
Reimbursement, Credit and Security Agreement dated as of August 1, 2000,
as amended by an Amendment dated as of November 29, 2002, an Amendment to
Loan Documents dated as of March 30, 2004, a Third Amendment to
Reimbursement, Credit and Security Agreement and Waiver dated as of July 25,
2006, and by a Fourth Amendment to Reimbursement, Credit and Security Agreement
dated as of January 29, 2007 (as so amended, the Agreement), pursuant to
which the Bank has issued a letter of credit for the account of the Borrower in
connection with the issuance of certain industrial development revenue bonds on
behalf of the Borrower.  B.The
Borrower has requested that the Bank amend certain financial covenants in the
Agreement and the Bank has agreed to amend the Agreement on the terms and subject to the conditions set forth
herein.  NOW, THEREFORE,in consideration of the
foregoing and for good and valuable consideration, the legality and sufficiency
of which is hereby acknowledged, the parties hereto, intending to be legally
bound hereby, agree as follows:  1.Definitions. Capitalized
terms used herein and not otherwise defined herein shall have the meanings
assigned to them in the Agreement.  2.Amendment to Agreement. The Agreement is hereby amended effective as
of the date hereof as follows:  (a)Section 6.21(a) is hereby amended and restated to read in
full as follows:  (a)IS&S, Inc. will maintain at all
times unencumbered cash and marketable
securities having a market value of at least $20,000,000.  (b)Section 6.21(b) is hereby deleted
in its entirety and replaced with the words Intentionally Deleted.  (c)Section 6.21(c) is hereby deleted
in its entirety and replaced with the words Intentionally Deleted.  3.Amendments to the Other
Documents. All references to the Agreement in the Collateral Documents or the Bond Documents and in any
documents executed in connection therewith shall be deemed to refer to the
Agreement as amended by this Amendment.


4.Ratification of the Other
Documents. Notwithstanding
anything to the contrary herein contained or any claims of the parties to the
contrary, the Bank and the Borrower agree that the Agreement and the Collateral
Documents and each of the documents executed in connection therewith are in
full force and effect and each such document shall remain in full force and
effect, as further amended by this Amendment, and the Borrower hereby ratifies
and confirms its obligations thereunder.  5.Representations
and Warranties.  (a)The Borrower hereby certifies that (i) the
representations and warranties of the Borrower in the Agreement are true and
correct in all material respects as of the date hereof, as if made on the date
hereof and (ii) no Event of Default and no event which could become an
Event of Default with the passage of time or the giving of notice, or both,
under the Agreement or the Collateral Documents exists on the date hereof.  (b)The Borrower further represents that it has
all the requisite power and authority to enter into and to perform its
obligations under this Amendment, and that the execution, delivery and
performance of this Amendment have been duly authorized by all requisite action
and will not violate or constitute a default under any provision of any
applicable law, rule, regulation, order, writ, judgment, injunction, decree,
determination or award presently in effect or of the organizational documents
of the Borrower, or of any indenture, note, loan or credit agreement, license
or any other agreement, lease or instrument to which the Borrower is a party or
by which the Borrower or any of its properties is bound.  (c)The Borrower also further represents that the
Borrowers reimbursement obligation under the Agreement is absolute and
unconditional, and there exists no right of set off or recoupment, counterclaim
or defense of any nature whatsoever to payment of such obligations.  6.Conditions Precedent. The amendments set forth herein shall be
effective as of the date hereof upon the fulfillment, to the satisfaction of
the Bank and its counsel, of the following conditions precedent:  (a)The Borrower shall have delivered to the Bank
the following, all of which shall be in form and substance satisfactory to the
Bank and shall be duly completed and executed:  (i)a fully executed counterpart of this
Amendment, including the Consent of Guarantors; and  (ii)such additional documents, certificates and
information as the Bank may reasonably request.  (b)The Borrower shall have paid to the Bank (i) a
nonrefundable modification fee in the amount of $2,500, and (ii) a document services fee of $500 for
documenting this transaction (which includes, among other things, fees and
expenses of the Banks outside and in-house counsel).  2


(c)The representations and warranties set forth in the Agreement shall be
true and correct on and as of the date hereof.  (d)No Event of Default, and no event which, with the passage of time or
the giving of notice, or both, would become such an Event of Default shall have
occurred and be continuing as of the date hereof.  7.NoWaiver.This Amendment does not and shall not be
deemed to constitute a waiver by the Bank of any Event of Default, or of any
event which with the passage of time or the giving of notice or both would
constitute an Event of Default, nor does it obligate the Bank to agree to any
further modifications to the Agreement or the Collateral Documents or
constitute a waiver of any of the Banks other rights or remedies.  8.Releaseand Indemnity. (a) Recognizing and in consideration of
the Banks agreement to the amendments provided herein, the Borrower hereby
waives and releases the Bank and its officers, attorneys, agents, directors,
and employees from any liability, suit, damage, claim, actions, counterclaims
or offsets, loss or expense of any kind or nature whatsoever and howsoever
arising, whether known or unknown and whether based on facts now known or
unknown, direct or derivative, that the Borrower, or anyone claiming in a
derivative capacity from the Borrower, ever had or has as of the date of this
Amendment against any of them including, without limitation, any of the
foregoing arising out of or relating to the Banks or such other Persons acts
or omissions with respect to this Amendment, the other documents executed in
connection herewith, the Agreement, the Collateral Documents, the Bond
Documents or any other matters described or referred to herein or therein.  (b)The Borrower further hereby agrees to
indemnify and hold the Bank and its
officers, attorneys, agents, directors and employees harmless from any loss,
damage, judgment, liability or expense (including counsel fees) suffered by or
rendered against the Bank or any of them on account of anything arising out of
this Amendment, the Agreement, the Collateral Documents, the Bond Documents or
any other document or instrument delivered pursuant hereto or thereto up to and
including the date of this Amendment; provided  that, the Borrower
shall not have any obligation hereunder to the Bank or such other Person with
respect to indemnified liabilities arising from the gross negligence or willful
misconduct of the Bank or such other Person.  3


9.Miscellaneous.  (a)All terms, conditions, provisions and
covenants in the Agreement and the Collateral Documents and all other documents
delivered to the Bank in connection therewith shall remain unaltered and in
full force and effect except as modified or amended hereby. To the extent that
any term or provision of this Amendment is or may be deemed expressly
inconsistent with any term or provision in the Agreement or any Collateral
Document or any other document executed in connection therewith, the terms and
provisions hereof shall control.  (b)This Amendment constitutes the entire
agreement of the parties with respect to the subject matter hereof and
supersedes all prior and contemporaneous understandings and agreements.  (c)In the event any provisions of this Amendment
shall be held invalid or unenforceable by any court of competent jurisdiction,
such holding shall not invalidate or render unenforceable any other provision
hereof.  (d)This Amendment shall be governed by and
construed according to the laws of the Commonwealth of Pennsylvania.  (e)This Amendment, and the Agreement and
Collateral Documents as amended hereby, shall inure to the benefit of, and be
binding upon, the parties hereto and thereto and their respective successors
and assigns and may be executed in one or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and
the same instrument,  (f)The headings used in this Amendment are for
convenience of reference only, do not form a part of this Amendment and shall
not affect in any way the meaning or interpretation of this Amendment.  [Signatures to appear on the following page]  4


CONSENT OF GUARANTORS  Each of the undersigned
guarantors (the Guarantors) consents to the provisions of the foregoing Fifth
Amendment to Reimbursement, Credit and Security Agreement (the Amendment) and
confirms and agrees that: (a) such Guarantors obligations under its
Guaranty and Surety Agreement dated as of August 1, 2000 (as the same has
been amended, the Guaranty), relating to the obligations of the Borrower to
the Bank shall be unimpaired by the Amendment; (b) such Guarantor has no
defenses, set offs, counterclaims, discounts or charges of any kind against the
Bank, its officers, directors, employees, agents or attorneys with respect to
the Guaranty; and (c) all of the terms, conditions and covenants in the
Guaranty remain unaltered and in full force and effect and are hereby ratified
and confirmed and apply to the obligations of the Borrower to the Bank, as
modified by the Amendment. Each of the Guarantors certifies that all
representations and warranties made by it in the Guaranty are true and correct
as of the date of the Amendment.  Each of the Guarantors ratifies and confirms the
indemnification, confession of judgment and waiver of jury trial provisions, if
any, contained in the Guaranty.  WITNESS the due execution of
this Consent as a document under seal as of the date of the Amendment,
intending to be legally bound hereby.  INNOVATIVE SOLUTIONS AND
  SUPPORT, INC.By:
  /s/ James ReillyName:
  JAMES REILLYTitle:
  CFOIS&S DELAWARE, INC.By:
  /s/ James ReillyName:
  JAMES REILLYTitle:
  CFO


IN WITNESS WHEREOF, the
parties hereto have executed this Fifth Amendment to Reimbursement, Credit and
Security Agreement as of the day and year first above written.   INNOVATIVE SOLUTIONS AND
  SUPPORT, LLCBy:
  Innovative Solutions and
  Support,
  Incorporated, its sole member and
  managerBy:
  /s/ James ReillyName:
  JAMES REILLYTitle:
  CFOPNC BANK,
  NATIONAL ASSOCIATIONBy:
  /s/ John M DinapoliName:
  JOHN M DINAPOLITitle:
  SENIOR V.P.  S-1