Pitot/Static Drains - Which planes have 'em?

[voretaq7]

A question on another site about water in pitot systems lead me to use the PA-28 pitot/static drain valves as an example of a system that's designed to let the pilot clear water from the lines, and it got me thinking: I've flown mostly Cherokees, and only one plane I've been in has had the pitot/static drain valves (it's either not installed or buried behind the side panel on all the others), and looking through the maintenance and parts manuals I can't seem to find a reference to them although they appear in at least one Warrior POH.

Do any of you know if there is some particular rhyme or reason behind which planes were/were not equipped with the in-cockpit drains for the pitot & static lines?

 

[Domenick]

 

[Ray93J]

 

[voretaq7]

 

[jruhnke]

 

[Domenick]

 

[5x5]

 

[DaveB]

 

[Charley]

 

[Cliff]