On December 21, 2003, about 1300 eastern standard time, a Cessna 310P, N5811M, registered to and operated by Crystal Aero Group Inc., as a Title 14 CFR Part 91 instructional flight, had the nose gear collapse while landing at Crystal River Airport, Crystal River, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The commercial-rated flight instructor and dual student were not injured, and the airplane incurred substantial damage. The flight originated minutes before the accident. The pilot stated that during takeoff/initial climb, at an altitude of about 500 feet, he placed the landing gear handle in the "UP" position, and during retraction, heard a loud bang, and the rudder pedals shuttered. He said he lowered the gear handle, and received a green light indication only the main gear. He then retarded the throttle levers to check for the landing gear warning horn, but the horn did not activate. He said he then performed the emergency gear extension procedure, but the nose gear did not extend, so he performed a low altitude "fly-by" to permit observers on the ground to visually examine the landing gear. According to the pilot, the observers reported to him that the nose gear appeared to be "down." The pilot said he then made a normal approach to land, and the landing rollout, as the airspeed decreased the nose gear collapsed, and the airplane skidded to a halt on the runway. Examination of the airplane's maintenance records showed that maintenance had been performed on the airplane's nose gear 11 hours prior to the accident, and 5 hours prior to the accident the airplane had received an annual inspection. Postaccident examination of the airplane's nose landing gear by an FAA licensed mechanic who had not previously maintained the airplane, revealed that the damage was consistent with the nose gear strut not receiving proper service, having deflated, and being out of alignment.