On July 4, 2017, at 1721 Atlantic daylight time, a Piper PA28-180, N9427J, operated by Horizon Aviation, was substantially damaged when it impacted the San Antonio Canal shortly after takeoff from Fernando Luis Ribas Dominicci Airport (SIG), San Juan, Puerto Rico. The private pilot and three passengers were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.According to the pilot, the purpose of the flight was to fly to a designated practice area, and return. Prior to the flight, the airplane was fueled. The pilot also calculated the weight and balance, performed a preflight inspection of the airplane and an engine run-up, with no issues noted. During the takeoff roll on runway 9, the engine instruments were "in the green" and the engine developed full power. During the initial climb at an altitude of about 250 ft above ground level, the engine started to run rough and lose power. The engine did not respond to throttle inputs. The pilot informed the air traffic control tower that he intended to return and land on runway 27. As the airplane flew toward a marina, the pilot recalled seeing people on the ground and wanted to avoid them. He did not recall the remainder of the accident sequence. One of the passengers was also a certificated pilot. He stated that the takeoff roll was normal, he observed the airspeed indicator at 60 knots, and liftoff was normal. The pilot flying then reported the engine was rough and radioed the control tower to request to return to runway 27. The passenger estimated the altitude to be around 200 to 300 ft at that time and he also noticed the engine roughness and loss of power, accompanied by vibrations. He stated that the pilot tried hard to avoid people on the ground. As the pilot was turning left, the passenger observed that the airplane was losing airspeed, and he saw the stall warning light flashing and he called out to the pilot "airspeed" a few times. He then recalled the airplane in a stall/spin attitude. A witness located at the marina recorded a portion of the flight on a video camera. A review of the recording revealed that about 20 seconds before impact, the airplane was flying relatively level in an easterly direction, for about 5 seconds, before being obscured by a water drop on the camera lens. About 7 seconds later, the airplane was visible again and on a southerly heading, toward the camera, in a left descending turn. The airplane's bank angle increased to about 90° left wing down, before it impacted the canal. The pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent first-class medical certificate was issued on October 9, 2012. Review of the pilot's logbook revealed that he had accrued a total flight experience of about 142 hours. His previous flight was on April 10, 2017, which was a "rental check" in the accident airplane. Review of the airplane's maintenance records revealed that the most recent 100-hour inspection was performed on March 25, 2017, about 90 hours prior to the accident. Additionally, the most recent annual inspection was completed on July 19, 2016, about 193 hours prior to the accident. The engine had accrued a total of 4,233 hours since new, and 937 hours since overhaul. Initial examination of the airplane by a Federal Aviation Administrator (FAA) inspector revealed that left wing was separated from the fuselage at the root, the right wing was partially separated at the root. The empennage was crushed in several locations, the left stabilator was partially separated and bent upward about 90° at its root. The throttle and mixture controls were found in the full-forward position, the carburetor heat control was in the off position. The fuel selector handle was in the right tank position, the electric fuel pump switch was in the "on" position. Both fuel caps were secure with their seals intact. The engine was drained of sea water, oil, and sediment for examination by an FAA inspector. The inspector removed the spark plugs and did not observe any wear or damage. The carburetor was removed from engine and no damage was noted. The inspector was able to rotate the propeller and obtain compression on all cylinders. The examination did not reveal any preimpact anomalies. An on-board video recording and the witness video recording were forwarded to the National Transportation Safety Board Vehicle Recorder Laboratory, Washington, DC. Review of the onboard video revealed that the airplane lifted off about 35.2 seconds elapsed time (all times are elapsed times). At 1:16.3, the airplane rolled slightly right. Between 1:18.7 and 1:19.7, the engine noise decreased. At 1:20.0, the airplane rolled level and the engine noise further decreased between 1:27.2 and 1:30.1. At 1:30.8, the airplane began to bank left. At 1:34.9, the airplane was in a descending left bank turn. Between 1:34.0 and 1:36.6, there was a momentary increase in background noise, consistent with an increase in engine noise. Between 1:36.8 and 1:37.7, the background noise decreased slightly, and remained at the same levels between 1:36.6 and 1:44.3. The sound of impact was recorded at 1:44.6. A sound spectrum study of the onboard video revealed that engine rpm was at 2,265 for about 7 seconds as the airplane was in the right bank. It then decreased to 1,980 rpm and the airplane began to bank left. The rpm momentarily increased to 2,292 about 5 seconds later, followed by a momentary decrease to 1,950, but remained stable between 2,373 to 2,451 rpm for about 6 seconds leading up to impact. The recorded weather at SIG, at 1729, was: wind from 070° at 14 knots; visibility 8 miles; thin scattered clouds at 3,500 ft; scattered clouds at 8,000 ft; temperature 29° C; dew point 25° C; altimeter 30.01 inches of mercury. Review of an FAA Carburetor Icing Chart for the given temperature and dew point revealed "Icing (glide and cruise power)."