On January 12, 2013, about 1500 eastern standard time, a Piper PA-28R-180, N3898T, operated by Flight School of Gwinnett Inc., was substantially damaged during a forced landing to a bog, following a total loss of engine power during approach to Barrow County Airport (WDR), Winder, Georgia. The flight instructor, private pilot and a passenger were not injured. The instructional flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the flight that originated from Gwinnett County Airport (LZU), Lawrenceville, Georgia, about 1430. The flight instructor stated that the airplane was in the airport traffic pattern at WDR, on a left downwind leg for landing on runway 23. Per the Before Landing checklist, the private pilot turned the fuel pump on and positioned the fuel selector to the fullest tank (right). The engine then ran rough and lost all power. The flight instructor took control of the airplane and verified that the fuel pump was on, the mixture was rich, and the landing gear was down. He then attempted to glide to runway 31; however, there was not enough time to align the airplane with the runway and it traveled off the right side, into a bog. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the right wing. The inspector noted adequate fuel in both fuel tanks. The engine was then started with the fuel selector positioned to the right fuel tank; however, it ran for about 10 seconds and lost all power again. After the wreckage was recovered from the bog, the inspector completed a further examination and noted that when the engine ran briefly, fuel leaked from the inlet side of the engine driven fuel pump. Examination of the pump revealed that the fuel pump line fitting O-ring seal was cracked. The airplane was manufactured in 1967 and equipped with a Lycoming IO-360-B1E, 180-horsepower engine. The airplane's most recent annual inspection was completed on November 7, 2012. At that time, the engine had accumulated approximately 1,578 hours since its last overhaul, which was completed in 1997. The airplane had been operated for about 15 hours since its most recent annual inspection. The FAA inspector added that the cracked O-ring seal might not be detected during an annual inspection, unless it was leaking fuel at that time; however, the engine manufacturer recommended an overhaul of the engine every 2,000 hours or 12 years, whichever came first.