Cowl mod
My other aircraft is a Twin Squirrel. Recently Eurocopter mandated a secondary latch system that was published as an AD. If you close the cowlings, the secondary system will latch in place. Even if the "primary " latches are not secured, the new "secondary" system will keep them attached to the airframe.
The bill was in excess of £10K and at the time, I thought it major overkill, especially as all the cowl latches are easily visible from the walk round. As in the Airbus, my other aircraft, 757/767, have latches at the six o'clock and I have never crawled under the engine to specifically physically check them as locked. I have always imagined the gap around the other sections of cowl would give away an unlocked cowl.
Perhaps Eurocopter have a neat idea?