I was going to mention Skydrol but as we don't use it in model aviation (not that I know of) I decided not to BUT you are dead right its lethal stuff to be avoided at all costs. I well remember doing the VC 10 ground school with BOAC, thats the FIRST thing they told us on the hydraulics section, the VC10 used Skydrol, avoid it, its dangerous stuff and a very effective paint stripper. It will, irrevocably, damage the cornea of the eye if splashed and the immediate treatment is copious irrigation with clean water. Years ago, concerned at the hazard of this fluid I recommended that an eyewash, ( sterile saline solution was the medical remedy proposed by my wife, an airline, Pan Am, nurse) , be placed on all of our aircraft in case of eye contamination and the correct first aid procedure was incorporated into our ops manual, its still there. In addition to that I would never go into the wheel wells of a 737 on walkround when the hyd systems were pressurised. (the pumps and reservoir are in there ) in the event of a leak a faceful of hyd fluid at 3000 psi could be seriously hazardous.

Its interesting to note that many aircraft stands at Australian airports have an eye/face wash facility for first aid treatment in the event of eye or facial contamination.

Thank you very much indeed for raising the issue, I had no idea Skydrol was used in Cessnas.

Regards, David Gladwin.