A320 IAE/CFM smoke?
 

Hi everyone,

I'm currently undergoing my A320 rating and I have a question which puzzles me. I've been working the past seven years as an aircraft refuelling operator and most ground staff regularly complains about smokey IAE engines after shut down. Plumes of smoke still emerging after 10-15 minutes. Never seen it on CFM, besides the regular puffs, so I take it it's a design issue. Someone throw me a good explanation besides dripping oil. :)

Unused fuel in the lines is sent to the combustion chambers for burn-off.

Not so for CFM.

Thank you very much.

Interesting response for IAE. However - the visible smoke means it isn't burned - not completely anyway.

A reverse iddle rollout and a 3 min or more taxi in reduces this black fummy smoke. It also reduces chances of a tail pipe fire.

I should have added:

I think it was to avoid dropping the unburned fuel onto the ramp after shut-down.

So why doesn't it occur after every shutdown?