Ed, Coefficient of Thermal Expansion of hydraulic fluid ~270,000 psi. Air in the system would make it very soft - think Ideal Gas Law - until the pressure gets really high. It would take a much larger change in volume to get a big change in pressure. Consider the nose strut. Pressure goes up as the strut is compressed over several inches. Now imagine the strut completely filled with fork-oil. It will still move, but not by much. Brakes systems are a different animal. They are not closed systems until the brakes are actually in use. Chris Chris Zavatson N91CZ 360std http://www.n91cz.net/ From: Ed Gray <egraylaw@swbell.net>To: lml@lancaironline.net Sent: Tuesday, September 4, 2012 1:18 PMSubject: [LML] Re: Temp effect on hydraulicsWhat is the coefficient of heat expansion on hydraulic fluid? Seems thatbig pressure changes would be caused by trapped air. Auto brakes don't failin low or high temps. Could it be trapped air in the fluid line to thesensor?Ed Gray L360 Nearly complete with test hours, Dallas-----Original Message-----From: Lancair Mailing List [mailto:lml@lancaironline.net] Sent: Tuesday, September 04, 2012 5:01 AMSubject: lml Digest #3893 Lancair Mailing List Digest #38931) Re: Critical Service Bulletin by Silvio Novelli <ppxsn@novellisouza.com.br>2) Barrett at fly-in by "Claudette Colwell" <colwell.ch@gmail.com>3) Re: Critical Service Bulletin on Cruise RPM by Silvio Novelli <ppxsn@novellisouza.com.br>4) Re: Critical Service Bulletin on Cruise RPM by Colyn Case <colyncase@earthlink.net>5) Re: Thermal influence on Hydraulic Pressure by "Danny" <danny@n107sd.com>6) Re: Thermal influence on Hydraulic Pressure by Frederick Moreno <frederickmoreno@bigpond.com>This digest is sent to you because you are subscribed to the mailing list <lml@lancaironline.net>.For archives and help clickhttp://mail.lancaironline.net:81/Lists/lml/List.htmlLML website: http://www.lancaironline.net/maillist.html--For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html