Here is a checklist which can really help you detect an issue before it becomes a real problem. You really should do a complete panel sweep upon level off and every hour thereafter. One of the problems with this step, however, is when something doesn't look right, we aren't really sure what right is. Here's what you need to do your very next flight: take a picture of each synoptic page and print copies for the cockpit.
Everything here is from the references shown below, with a few comments in blue.
[G450 Airplane Flight Manual §2-05-20]
Photo: Tail camera video, from Eddie's aircraft.
Don't skip this page! In the daylight you can see all of the top of the engines, the top of the fuselage, and about half of each wing.
Photo: ECS synoptic, from Eddie's aircraft.
From top to bottom:
Photo: Doors synoptic, from Eddie's aircraft.
If you are worried about a door or a panel, it would be helpful to know which doors and panels you might see on this synoptic: [G450 Aircraft Operating Manual §2B-05-00 Figure 89]
Figure: Doors synoptic, from G450 Aircraft Operating Manual, §2B-09-210, figure 42.
In the G450 the Doors synoptic reflects all but two external doors: the nose landing gear door pin door and the nose landing gear control valve door. Fortunately, both of these door trail aft.
Figure: Doors synoptic, from G550 Aircraft Operating Manual, §2B-09-250, figure 43.
In the G550 the Doors synoptic reflects all but three external doors: the nose landing gear door pin door, the nose landing gear control valve door, and the external air door. Fortunately, all three of these door trail aft.
Photo: Hydraulics synoptic, from Eddie's aircraft.
Reservoir temperatures are green between 79°F and 104°F, white when below 79°F, and amber when above 104°F. [G450 Aircraft Operating Manual §2A-29-20 para;2.G.]
We normally do see 3,000 psi in the left and right systems. The resolution of the system is 100 psi so if you see anything else for a sustained period, you might have a problem.
The left system quantity is considered low below 2.0 gallons, the right is low below 0.53 gallons. [G450 Aircraft Operating Manual §2A-29-20 ¶2.C.(3)]
The accumulators will drop with altitude and turn amber. Don't worry about it, they will come back as you descend.
Photo: Fuel synoptic, from Eddie's aircraft.
[G450 Airplane Flight Manual §1-03-80] Fuel Load Balancing: Maximum permitted unbalance is 2,000 lbs at 55,000 lbs gross weight, decreasing linearly to 400 lbs at 60,500 lbs gross weight.
[G450 Airplane Flight Manual §1-28-30] Maximum: Fuel temperatures of +54°C or greater will cause a Red Fuel Tank Temperature message to be displayed on the Crew Advisory System (CAS).
[G450 Airplane Flight Manual §1-28-30] Minimum: For airplanes S/N 4001- 4244 without ASC 908B, 909 or 910 (or later approved revisions):
[G450 Airplane Flight Manual §1-28-30] Minimum: For airplanes S/N 4001-4244 with ASC 908B, 909 or 910 (or later approved revisions) and 4245 and Sub:
Photo: Flight controls synoptic, from Eddie's aircraft.
In cruise flight the pitch trim is normally right around zero.
The horizontal stabilizer should be at -1.00 ±0.25° with the flaps up. [G450 Aircraft Operating Manual §2A-27-50 ¶2.B.]
Photo: AC synoptic, from Eddie's aircraft.
Our left AC generator tends to run a bit higher than the right, but never more than 30%. That, of course, translates to DC as well . . .
Photo: DC synoptic, from Eddie's aircraft.
These numbers are likely to be different depending on how your airplane was completed. We've become used to the left main TRU running in the 30's while the other three are in the 20's.
There is some debate on the advisability of updating the FMS fuel quantity on a regular basis. The FMS gives you a scratch pad warning if the gauge amount differs from the FMS quantity by more than 2% of the programmed BOW. If, for example, you have a BOW of 44,000 lbs, you will get a warning when the FMS quantity differs from the gauge by more than 880 lbs. This happens regardless if the quantity is updated or not. I recommend doing the update but make sure you take note of the discrepancy and get a feel for how accurate your FMS predicts actual fuel usage. I would like to know about a fuel leak before it gets to 880 lbs and know that my aircraft's FMS has never been off more than 200 lbs off after level off or 100 lbs during an hourly cruise check. If I saw twice those numbers, I would immediately suspect a fuel leak.
Gulfstream G450 Aircraft Operating Manual, Revision 35, April 30, 2013
Gulfstream G450 Airplane Flight Manual, Revision 35, April 18, 2013
Gulfstream G550 Aircraft Operating Manual, Revision 27, July 17, 2008