St. Louis, Missouri, January 7, 2008 – Aerospace Filtration Systems, Inc. (AFS) has received a Supplemental Type Certificate (STC) from the Federal Aviation Administration (FAA) for an Inlet Barrier Filter (IBF) system for MD Helicopters' MD900 Explorer series. The certification clears the way for MD Explorer operators to maximize engine protection while reaping performance and maintenance benefits available with an IBF.

AFS IBF-equipped MD900 helicopters can freely operate with no engine inlet imposed flight or gross weight restrictions. AFS representatives said paperwork is also being submitted for European EASA approval of this inlet barrier filter design, extending the AFS solution for more operators outside the continental US.

The IBF system for the MD900 features dual long-life conformal filter assemblies, readily mounted on the existing inlets. Inlet bypass capability is achieved utilizing the existing MDHI bypass system which is part of the Inlet Particle Separator (IPS) modification. Sturdy conformal inlet covers are standard with the system for added protection during non operating conditions. And the new IBF system is available as a factory direct option on the MD900/902 Explorer.

AFS and its parent Donaldson Company lead the industry with innovative and state of the art inlet protection technologies. In the case of the MD 900 Donaldson/AFS provide both the IPS and the IBF to MD Helicopters for production aircraft.

About Aerospace Filtration Systems, Inc.
AFS is the industry leader in the design, development and manufacture of high-performance engine IBF systems for commercial and military propulsion systems. The company manufactures certified IBF solutions for the Eurocopter AS350 B/BA/B1/B2/B3 (AS350D/SD/SD2-Soloy STC), AgustaWestland AW119 Koala, Bell 205A1, 206B, 407, 206L-3/4, 206L-1(C30) and MD Helicopters MD 369 (MD 500H/D/E/F Series) and MD 900/902 Explorer. IBF systems for the Eurocopter EC 130, Bell 430 and AgustaWestland AW139 are in development. AFS is a wholly owned subsidiary of the Donaldson Company, Inc. Traded on the NYSE under the symbol DCI, Donaldson is a member of the S&P MidCap 400 Index. Additional company information for AFS and DCI is available at www.afsfilters.com and www.donaldson.com.

Visit AFS at Booth 4013 during the upcoming HELI-EXPO 2008 in Houston, Tex., February 24-26, 2007.

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For more information, contact:
Aerospace Filtration Systems, Inc.
Sales and Marketing
(636) 300-5200
sales@afsfilters.com
www.afsfilters.com