Copyright © 2016  Grand Rapids Technologies, Inc.                      



Electronic Flight Instrumentation for Experimental Aircraft Since 1991

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Contact Us

Phone: (616) 245-7700

Fax: (616) 245-7707

GRT Avionics, Inc.

3133 Madison Avenue SE

Wyoming, MI 49548

General Sales: sales@grtavionics.com

Tech Support: support@grtavionics.com


Company History

Greg Toman founded Grand Rapids Technologies, Inc. in 1991 after seeing the need for an automated engine monitor with alarms that accurately measured exhaust gas and cylinder head temperatures for 2-stroke engines used in ultralight aircraft. Since then, the Engine Information System (EIS) has become the industry standard and instrumented over 25,000 engines, from small 2-stroke to turbines, all around the world.


In 2003, Greg partnered with long time friend and fellow pilot, Todd Stehouwer, to develop the Horizon Series 1 EFIS (Electronics Flight Instrument System), bringing modernization to experimental and light sport aircraft, including primary flight instruments, navigation and engine monitoring. Their new company was called GRT Avionics.


Grand Rapids Technologies, together with GRT Avionics, employs 8 full-time personnel. All GRT hardware is manufactured in Wyoming, Michigan, a small industrial suburb of Grand Rapids.



Engineers with a Passion for Experimental Aviation

Greg Toman has a Bachelor of Science Degree in Electrical Engineering from Michigan State University. Before starting Grand Rapids Technologies, Greg worked for Boeing and Lear-Seigler, now GE Aviation. In both companies Greg participated in the development of avionic systems for military and commercial aircraft; including the Boeing 737, Lockheed C-130 and McDonnell Douglas A-4 Skyhawk. Greg has flown many hours in his vintage Cessna 140 and a Challenger ultralight. He currently owns and flies a Van’s RV-10 and is building his own RV-10 in his basement.


Todd Stehouwer has a Computer Systems Engineering Degree from Western Michigan University. Following graduation, Todd designed embedded hardware and software for test equipment and CNC controls.  In 1999, Todd founded Princeton Electronics, producing solid state fuel level probes for experimental aircraft and other industries. Todd has owned and flown a Cessna 120 and Challenger ultralight, and is currently restoring a Van’s RV-6.


Hours of Operation

General Inquiries & Sales: Monday-Friday  9 AM - 5 PM  

Tech Support:  Monday-Friday  10 AM - 12 PM and 2 PM - 4 PM

All times are Eastern (EST)