Modification and installation of cabin heat duct
The KAI plans call for M3 rivnuts to provide attachment points for the cabin heat flap valve. M3 has been abandoned everywhere else, replaced with M4 and this will be done here. Four of the six rivnut locations are shared with the cabin heat duct. The flange width is already marginal for M3 rivnuts, but totally useless for M4 rivnuts. So doubler flanges were created that are rivetted to the body of this duct, while providing enough material for the use of M4 rivnuts. This doubler was made from 0.8mm sheet
The doubler flanges attached. The negligible edge distance of the original flanges are visible here. In retrospect I might have cut the original flanges away completely, but the minimal material is ok to serve as a washer function in this non-structural connection. JB-Weld will also be used on the rivnuts, as usual.
View from cabin side
Longer grip range M4 rivnuts were used at the locations where the flange is present.
View from interior, ugly but functional
This is a revised part, from another builder's kit. A much improved edge clearance, even when upsized to 6mm
Author
This post is from Adam Dickson
