From: Larry Visoski

From: Larry Visoski To: Je vacation <jeevacation®gmail.com> Subject: Fwd: Cabin Temp Issues on G550 SN 5173 [2364871:2050229] Date: Sat, 02 Sep 2017 20:32:34 +0000 Attachments: Low_Limit_valve_Joumal.pdf; PAC_OUTLET_TEMP_RISE_AT_fl430.docx From Tech support Sent from my iPhone Begin forwarded message: From: "Allan, Jeff' Date: September 2, 2017 at 4:33:47 PM GMT+2 To: Subject: Cabin Temp Issues on G550 SN 5173 [2364871:20502291 Good Day Larry, As we discussed, there are three issues going on with the aircraft one normal and two possibly abnormal. First, above FL410 the turbine bypass valve opens which is normal. When this occurs the cooling turbine slows down and the pack outlet temp can warm up slightly. Second, you may have two bad low limit valves. what happens is the seals go bad on the butterfly portion of the valves and allow a small amount of warm air to leak by. If you already have a warmer outlet due to the slowing down of the cooling turbine, this can compound the issue. Third, when flying through warmer than expected ISA temps this further compounds the two above issues. You also mentioned that you thought one of your temp sensor fans was not working; that will cause issues in auto if that is the case. If you go to Luton, I would have them look at the low limit valves and check the cabin temp sensors and fans. Also ensure the sensors are clean and their inlets not obstructed. I have attached a couple of documents to further explain the situation. Regards, Jeffrey Allan Gulfstream Technical Operations La e Cabin Mechanical S stems (Direct) 912-965-4178 x 1131031(Toll Free) 800-810-4853 a This Technical Data is controlled under the Export Administration Regulations by General License TSU. It may not be transferred to a third party without prior written approval of the Department of Commerce. EFTA01036236 This e-mail message, including all attachments, is for the sole use of the intended recipient(s) and may contain Personal Information under General Dynamics policy CP 07-105 and/or legally privileged and confidential information. Any Personal Information can be accessed only by authorized personnel of General Dynamics and its approved service providers and may be used only as permitted by General Dynamics and its policies. Contractual restrictions apply to third parties. If you are not an intended recipient, you are hereby notified that you have either received this message in error or through interception, and that any review, use, distribution, copying or disclosure of this message or its attachments is strictly prohibited and is subject to criminal and civil penalties. All personal messages express solely the sender's views and not those of Gulfstream Aerospace Corporation. If you received this message in error, please contact the sender by reply e-mail and destroy all copies of the original message. EFTA01036237