DE-ICE FLUID ACCUMULATED IN AN HS800 XP APU INLET LOW POINT BAFFLE AND SUBSEQUENTLY ENTERED THE AIR CONDITIONING; FILLING THE CABIN WITH SMOKE ON TKOF ROTATION.

Narrative

SMOKE IN THE ACFT CABIN RESULTING FROM DE-ICE FLUID INGESTION IN TO THE ACFT'S AUXILIARY POWER UNIT (APU). EVENT RESULTED IN EMER RETURN TO THE ARPT. LATER RESEARCH INTO THE SITUATION WOULD REVEAL THIS IS AS A KNOWN PROBLEM BY THE ACFT MANUFACTURER. DE-ICE FLUID CAN POOL WITHIN THE AIR INLET DUCT OF THE APU WHICH CAUSES INGESTION UPON TAKEOFF ROTATION. THIS EFFECTIVELY DELAYS THE RESULT OF THE INGESTION UNTIL TAKEOFF. THIS HAZARD IS NOT NOTED IN ACFT'S POH AND HAS NOT BEEN PROPERLY COMMUNICATED TO OPS.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THE AMOUNT OF SMOKE IN THE CABIN AND FLT STATION WAS SURPRISINGLY LARGE. WHEN IT HAPPENED THERE WAS NO DOUBT THAT THE ACFT WAS RETURNING IN AN EMER CONDITION. BACK AT THE ARPT; THE CREW DID SOME RESEARCH ABOUT THE CAUSE OF THIS EVENT AND DETERMINED THAT THE APU AIR INLET IS DESIGNED SO THAT A LOW POINT BAFFLE ALLOWED FLUID TO SIT AT THE LOW POINT AND BE BYPASSED BY THE INLET AIR. HOWEVER AT ROTATION THE FLUID IS SUCKED INTO THE INLET AND SUBSEQUENTLY THE AIR CONDITIONING SYSTEM. THE RPTR COULD FIND NO REFERENCE TO THIS DESIGN IN ANY OF THE MANUALS AVAILABLE TO HIM.