Van’s Redesigns FAB Airbox for Carbureted Models

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The FAB air box on a carbureted RV.

Rian Johnson, President and Chief Technical Officer at Van’s Aircraft, is a hands-on kind of leader. Not many people know it, but Rian build the very first RV-7A. Wearing his engineer hat, he tackled the recurring problem of wear and tear in the FAB air boxes in carbureted models (RV-3,4,6,7,8,9 and 10).

The top plates of the air boxes have been fracturing as a result of engine shake during shut downs. At shut down, an engine will shake like a wet dog, while the cowling remains stationary. This results in the airbox (that is attached to the engine) coming into contact with the fixed cowling and imparting stresses on both structures. In addition, the alternate air door needed some redesign to beef up the whole mechanism.

By redesigning the airbox to be asymmetrical, Rian eliminated vibrational interference. He also added a silicone seal to the air box inlet and reinforcing washers to the portion of the top plate that bolts to the carburetor. Finally, Rian completely redesigned the alternate air door to make it operate easier with less wear and tear. All of these parts are adaptable to any of the carbureted RVs (except for the 12) and can be ordered directly from Van’s.

Redesigned alternate air door for the FAB.
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Steve Ashby is a sometime lawyer and full-time aviation aficionado from Atlanta, Georgia. He learned to fly in 1980 and has adopted a 1968 Skyhawk (your Grandma could fly it). Steve is also working on a Van's RV-8A which he swears will be completed on (a) Thursday.

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