I have always carried a 1.4 lb Halotron (inert gas, no chemical residue) fire extinguisher in my STOL 750.  I mounted it behind the passenger's seat, but never liked that location, fearing access might be blocked if something in the baggage area shifted forward, etc.

I recently experimented all around the forward cockpit but couldn't find a satisfactory location for ease of access and avoiding being kicked.  A common, ideal location is against the seat support below the pilot's knees, but with my dual sticks, that area has the dual stick linkage running through it.  I did not want to mount the extinguisher in the lower baggage area since ease of access and possible entanglement with cargo could be an issue.

It suddenly occurred to me that since I have a 1.75" o,d, tubular steel support running across the baggage area to mount my 4-point Crow harnesses at the proper angle (the discussion of this project is here), a roll-bar type mount might be the ideal solution.  I got the mount from Amazon and it was only $30 with a coupon, but I was impressed with the construction - all aluminum and powder coated.  It came with two massive clamps for the 1.75" tube, but they seemed heavy and I opted instead for the stainless screw clamps covered with heat shrink (all included with the mount).  The area against the tube is curved to match the radius of the tube and covered with rubber for increased grip ... it's quite secure and absolutely will not rotate on the tube!

The extinguisher is released by pulling the spring-loaded red knob and swiveling the extinguisher down and out.  The only negative is that it requires two hands - one to hold the red knob out and one to grab the extinguisher.  However, there's lots of times in-flight I've held the dual stick between my knees momentarily to free both hands, so that wouldn't be a serious problem and on the ground, not a problem at all. 

I know this isn't a common 4-point mount but there are a few who have copied my design and might find this useful if considering an extinguisher mount.  For those without the cross-tube, I don't see why this couldn't be adapted to a roof mount (with a proper reinforcing gusset) - they make the same mount for attaching to flat surfaces and it even costs less!

John

N750A