I don't think it would be easy to intoduce a limit to the amount of hours engineers can work but maybe a restriction like not been allowed to certify after 16/18 straight hours on duty might help.
Its all down to money, the management and accountants will visit the engineers line office during the morning or afternoon on a weekday when at least half the aircraft are flying and they'll see x amount of engineers sitting around looking at the AMM or drinking tea or watching tv etc ( sorry drinking tea or looking at tv or looking at the AMM etc
) and they think there's plenty of engineers.
They never visit at 3 O'Clock on Saturday or Sunday morning when one lad is on holidays another sick and all the aircraft are down with defects and need to be serviceable before 0700 so one of the day shift had to stay behind to help out as there was just too much to do.
NAA audits are also the same, they are always during a weekday and are nearly always planned so there's always plenty of staff.
I can't remember thet last time I saw a random audit?
