Narrative:

Sitting in the right seat acting as check airman; I was performing an enroute check for a upgrading captain. We were nearly home; overhead our final destination; ZZZ; at 3000 ft on vectors for an ILS (VMC) approach; when passengers reported a smoky haze or fog in the cabin. I could smell an oily; unburnt fuel/oil scent and looking back to the cabin behind me noticed there was a foggy haze that seemed to be increasing. As we were overhead our intended destination; we elected to get the aircraft on the ground as soon as possible. We donned our oxygen masks; notified ATC and were switched from approach control to the tower. The tower cleared us to land. Performing a visual short approach; we landed without incident. We taxied off the runway and stopped/shutdown on the taxiway. There was no more evidence of increasing smoke now that the engines and APU were shutdown. Of course; not knowing the reason for the fog; we immediately evacuated passengers off the aircraft and were able to secure the aircraft. Fire/rescue equipment arrived and it was determined the was no fire risk and no further action was needed. Looking back on our response to the event; I'm glad we correctly accomplished the emergency checklist memory items; although I will say donning the oxygen mask took more time than I expected. I had to first remove my headset; (just when I really would've liked to still be in contact with ATC); then my baseball cap and sunglasses; don the oxygen mask; switch mic sources and then put my headset back on. Taking about twenty seconds; this happened at a time where the PF (pilot flying) was making a descending 180 deg turn for a short approach and landing. Given the brief amount of time remaining before touchdown; we completed the before landing checklist. In circumspect and in talking with our mechanic and his maintenance resources; we are inclined to believe there was no fire; but an occurrence where a bearing oil seal opened inside one of the engines; (or APU); which leaked oil into a compressor section; (a source for cabin bleed air). The compressor section subsequently vaporized the oil; filling the cabin with an oily; smelly fog. The fog dissipated as we landed and reduced power. After landing we saw there was no observable damage or change to the outside of the aircraft or inside cabin; only a pervasive oily smell inside.

Related reports:

Google
 

Original NASA ASRS Text

Title: CE-560 XL flight crew reported an uneventful emergency landing due to fume/smoke in passenger cabin.

Narrative: Sitting in the right seat acting as Check Airman; I was performing an enroute check for a upgrading Captain. We were nearly home; overhead our final destination; ZZZ; at 3000 ft on vectors for an ILS (VMC) approach; when passengers reported a smoky haze or fog in the cabin. I could smell an oily; unburnt fuel/oil scent and looking back to the cabin behind me noticed there was a foggy haze that seemed to be increasing. As we were overhead our intended destination; we elected to get the aircraft on the ground ASAP. We donned our oxygen masks; notified ATC and were switched from Approach Control to the Tower. The Tower cleared us to land. Performing a visual short approach; we landed without incident. We taxied off the runway and stopped/shutdown on the taxiway. There was no more evidence of increasing smoke now that the engines and APU were shutdown. Of course; not knowing the reason for the fog; we immediately evacuated passengers off the aircraft and were able to secure the aircraft. Fire/Rescue equipment arrived and it was determined the was no fire risk and no further action was needed. Looking back on our response to the event; I'm glad we correctly accomplished the emergency checklist memory items; although I will say donning the oxygen mask took more time than I expected. I had to first remove my headset; (just when I really would've liked to still be in contact with ATC); then my baseball cap and sunglasses; don the oxygen mask; switch mic sources and then put my headset back on. Taking about twenty seconds; this happened at a time where the PF (pilot flying) was making a descending 180 deg turn for a short approach and landing. Given the brief amount of time remaining before touchdown; We completed the before landing checklist. In circumspect and in talking with our mechanic and his maintenance resources; we are inclined to believe there was no fire; but an occurrence where a bearing oil seal opened inside one of the engines; (or APU); which leaked oil into a compressor section; (a source for cabin bleed air). The compressor section subsequently vaporized the oil; filling the cabin with an oily; smelly fog. The fog dissipated as we landed and reduced power. After landing we saw there was no observable damage or change to the outside of the aircraft or inside cabin; only a pervasive oily smell inside.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.