On June 5, 2008, about 0840 eastern daylight time, a Cirrus SR20, N475DA, incurred minor damage when the nose landing gear collapsed during a landing at Orlando Sanford International Airport (SFB), Sanford, Florida. The certificated flight instructor and the student pilot were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight, operated by Delta Connection Academy Inc., under the provisions of 14 Code of Federal Regulations Part 91. According to the flight instructor, he noted a "shimmy" in the nose landing gear during the first three landings, but did not think it was out of the ordinary. During the fourth landing, the student pilot "did not flare enough, which resulted in a three-point landing" and a subsequent "porpoise" of the airplane. The flight instructor reported the airplane bounced two or three times before he took control and taxied clear of the runway. The instructor also stated that there were no abnormalities during the taxi back to the runway for takeoff. The flight instructor, who had control of the airplane during the next landing, reported that the airplane touched down first on the main landing gear, and that the nose landing gear "touched down sooner than expected." The instructor then raised the nose of the airplane again to smooth the roll-out. When the nose landing gear settled back onto the runway, the nose of the airplane "continued to dip well below the normal position and fell onto the runway surface." The flight instructor reported a total time of 420 flight hours, with 167 hours in the incident airplane make and model. His most recent Federal Aviation Administration (FAA) first-class medical certificate was issued on May 19, 2006. The student pilot reported a total time of 66 flight hours. His most recent FAA first-class medical certificate was issued on September 28, 2007. The reported weather at SFB, at 0837, included winds from 190 degrees at 4 knots, clear skies, and an altimeter setting of 30.09 inches of mercury. Post incident inspections conducted by the operator's maintenance personnel revealed that the nose landing gear strut weldment had cracked. The incident prompted the flight school to inspect its entire fleet of Cirrus SR20 airplanes, of which, nine others exhibited cracking in the same location as the incident airplane. According to the operator, the airplane's most recent 100 hour inspection was completed on May 14, 2008. As of that date, the airplane had accumulated 769 total flight hours. The airframe manufacturer subsequently issued a service bulletin, mandating an inspection of the nose landing gear assembly for cracking. According to the service bulletin, airplanes were to be inspected within the next 15 flight hours, and every 100 hours thereafter. If any cracks greater than 0.19 inches were detected, the nose landing gear strut was to be replaced with an "improved" nose landing gear strut.