From: Lvjet Sent: Friday, July 15, 2016 2:52 PM To: [email protected] Subject: GIV update Jeffrey I spoke to Tech ops, John and Mike,. Normal PSI in Duct pressure at FL450 (45,000') is 19 to 22psi, it varies with Density Altitude and Temperature slightly. Mike indicated that Gulfstream does not like the term "Buffet" or "Vibration" they use the term "TRIM Variance" if the exhausted air from pylon precooler air modulation valve was not equal to both L/H and R/H the air is disrupted over the tail section of the aircraft Causing a TRIM VARIANCE. I informed Mike that we had to change the Gasket on L/H anticipator and found a Loose Temp sensor in Left Pylon, and we changed the R/H pylon Anticiptor gasket as a precautionary measure. Now that Bleed system Duct pressure is tight and equal, Mike feels the aircraft is operating at factory specs, Depending on pressurization Bleed system requirements, the Duct pressure will vary when 12th stage bleed valve opens for decent. during climb the duct pressure can read as high as 40psi, since the HP Bleed valve located on each engine is set to modulate exhausted air at 40PSI max into the cabin,. if air was blowing by the Anticipator gasket, this effects the amount of air into the cabin, since the Anticipator is anticipating the 400 degree air, and adjust the HP regulator valve accordingly. We have changed Both HP Regulator valves about a year ago,. so they are good on both engines. Equal temps and PSI on the panel in Radio rack are important information, for smooth ops. thx Larry EFTA_R1_00106322 EFTA01784770