On April 5,1999, at 0945 eastern daylight time, a DeHavilland DHC-6-200, N838MA, collided with the ground during a single-engine go-around to runway 15 at the Palm Beach County Airport in Lantana, Florida. The non-scheduled air taxi flight was operated by Carib-Air Cargo Inc., under the provisions of Title 14 CFR Part 135 with a visual flight rules flight plan filed. Visual weather conditions prevailed at the time of the accident. The commercial pilot and four passengers were not injured, and five passengers received minor injuries. The airplane sustained substantial damage. The flight departed Lantana, Florida, at 0942. The pilot reported that prior to takeoff, he completed a preflight inspection of the airplane that included checking the engine oil quantity. After the oil levels were checked it was determined that additional engine oil was needed. The line personnel topped off the oil reservoirs, and reportedly secured the engine oil reservoir filler caps. The pilot also stated that he rechecked the oil cap after the oil was added and no one else touched the oil caps before the flight departed. According to the pilot, approximately two minutes into the flight, the right engine oil pressure warning light illuminated. The pilot informed Palm Beach Approach Control of the engine oil pressure problem. The pilot shut down the right engine, feathered the right propeller and returned to Lantana. As the flight approached runway 03, the pilot heard a radio transmission from another airplane taxiing for takeoff. As the pilot continued the approach, with full flaps extended, he elected to go-around 1500 feet from the approach end of the 3000-foot runway. The airplane collided with the ground during the go-around maneuver to runway 15. The pilot said he never saw the other airplane on runway 03 during his initial approach. An examination of the crash site revealed that the airplane was in a nose low attitude. The airplane was orientated 180 degrees from the departure heading. The examination of the airplane also disclosed that the left wing assembly separated from the rear attach point. The airplane examination revealed that the right propeller was in the feather position. Also the nose was destroyed, the nose wheel separated from the airplane. The wreckage examination also disclosed that the right cowling showed oil streaming back from behind the engine and onto the wing strut. Inspection of the oil filler cap revealed that it had not been properly installed.