Good points raised with respect to outflow valves etc.
Recently a flight crew reported that the cabin staff had felt light headed and felt mildly ill complaining that the air con was to blame. This was on completion of the first sector they then continued for three more sectors including a stopover at a maintenance base with no more reports.
The captain asked if he should write this in the tech log for an action. At this I said "of course" especially in the light of the on-going problems. I also then added that there should be a air safety report raised that I would be grounding the aircraft until I was satisfied that The fault was a one of or I had in fact found something. Also the crew that had this complaint should go to a medic and be checked out.
At this he backed down and just asked if i could look at it unofficially. This I done to satisfy my own peace of mind with no faults found.
The manufacturer of the aircraft has addmitted that there is a problem and in response a sil has been issued to be carried out at 500cyc/hrs. Our particular operator also carries out the first part of it each week. The base that i am at now has carried this out over a hundred times in the last eight months and nothing has been found.
May I suggest that the opperating procedures be reviewed by the crews for initial start up of air con on the 146. If it not started in manual when cold, the system runs full hot until a controling Cabin temp of 12 degrees is reached which unfourtunately by design of the system does produce a cabin smell temporarily. So please APU on wait a few mins. APU air on wait air con to man set to full cold then packs on and slowly increase temp.
If any crew wish to discuss this further please send a private mail.