Like Jim said there are many things that can contribute to fruit drop from wind, storms, critters, and drought to things like overbearing or lack of pollination or not enough overlap between bloom times with compatible pollinating varieties. The key thing you said is the trees are loaded so I'd rule out pollination and place my money on overbearing. Fair warning if you don't thin your fruit and most of the fruit ripens you'll either fail to have a crop next year or it will be very minimal. Good luck and I hope this helps.
