With much attention to detail, Boeing successfully discovered the many design changes that are required when using passive cooling. Environmental changes such as component placement and mounting all circuit boards vertically often are overlooked. By placing the hottest components at the bottom of a vertical circuit board, they have the first contact with cooler air. By paying attention to detail and creating efficient natural convection designs, Boeing successfully redesigned a critical flight control system to run cooler for longer periods of time with no fans.
Designers are no longer limited in placing avionics computers only where access to mechanically cooled or forced air exists. Boeing saw the advantages of natural convection cooling and realized its application to the next generation of “integrated avionics approach.”