Citation X (C750)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General None Reported / Taken
Aircraft
I was Pilot Not Flying. One passenger onboard; he was very helpful during event. During descent around FL300; both crew members smelled a strong burnt electrical smell. We never saw smoke but passenger came up immediately and said 'did you see that puff of smoke?' and pointed to outlet or lower pedestal area of cockpit (near parking brake; etc.). Something similar had just happened to another crew and tail yesterday (their outlet fried); so I unplugged my charger immediately; turned off the interior master and turned off the wifi. Passenger said it smelled like when a hairdryer burns itself. Notified ATC of the odor and we got an early descent on the arrival. Couldn't identify the source of the smell; no visible smoke and the smell had dissipated; so we considered it could have been a blown fuse or wire somewhere. Once everything was briefed; I checked on the passenger. Smell was much less pungent in the cabin. Told him we are descending early and that if the smell came back; we would drop the masks and get down quick. Reminded him about the fire extinguisher. On about a 5-mile final; the smell returned so we turned off the cockpit pack which helped. We had to leave the plane with a mechanic and quickly go get another plane ready for a different live leg; but it sounds like it turned out it was a bad pack and not anything electrical in the cockpit. Now I know that depending on how a pack goes bad; a fried pack can sure look and smell like an electrical issue; and not just the typical pack smell of dirty sock.
C750 pilot reported a burnt electrical smell during descent. Initially they thought it was the Flight Deck 120 Volt outlet; but they later found out that it was a bad pack.