Black dust

[prin]

Anyone know why we have black dust like graphite on the counter and near the fridge? It has been happening since we got the 184 last year. we also seem to have a wiring problem-- the propane detector goes off when there is no propane being used nor has there been and the only way to get the detector to turn off is out the porch lighten--not fun so it is off to see what is wrong.
any help with the dust issue greatly appreciated
Jane & John Olds
"Roadie" our Clumber spaniel
and Kerrmie the green MPG 184

 

[hoefler]

Sewer gas and a fart will set off the propane detector. As far as the dust, do you travel with any windows or vents open?? I get a similar dust covering the rear of the rig after a days travel.