Quite a few times I've been on a plane where engineers are working on one of the engines (or at least one cowling has been up). Both pilot and co-pilot having been sitting up front -- the walk around presumably having been done. - yes
The cowlings have been shut and off we go. There comes a point where you surely do have to trust the professionalism of others. - yes
Or are you meant to leap out and have a decko? - no. This sort of work would normally require a Tech Log entry to clear which the eng would need to come into the cockpit, and you cannot 'accept' the aircraft until the entry is cleared. Nothing to stop you, of course 'leaping out' (ah! - in my younger days.....
), but if you cause a 'delay' to 'doors closed'/push back you may be asked (by a 'suit') why you did not 'allow' the system to work.
I assume baggage hold doors which are generally shut minutes or seconds before departure are not subject to being checked because there are warning lights in the cockpit to indicate that something is open.- yes
It is all about 'trust' in a team. There are other hatches which may be opened for servicing but have no 'warning system'. I hoped in my time that the pax like you 'trusted' me to operate safely, although admittedly there was a distinct personal incentive so to do as I was going to be in the same aircraft
