Today I drilled the Garmin SL-40 and GTX-330 trays to the instument panel support angles. Then I marked the subpanel where the trays pass through and cut the opening. After a few iterations the trays fit the opening well. Finally I fabricated siffener and support angles for the forward side of the subpanel around the tray opening and drilled the angles to the subpanel.
Transponder and comm trays drilled to the instrument panel support angles
Subpanel tray pass through opening cut
The forward side of the subpanel with trays and support angles clecoed on
