I didn't tighten all screws and nuts before a flight last night and a blade came off while it was about 20 meters above pavement with a pretty good forward velocity going. I felt like NTSA while doing my grid search of the crash. I found my GoPro (mount snapped off in-flight due to stress of abrupt change of direction), then the battery, then the SD card, then the blade. Never did find the blade fastener nut (new ones on order). Good news is the aircraft itself is fine. Upon closer inspection I also realized that my landing gear screws were coming out. I will be checking all those fasteners before plugging in the battery before each flight now.