On April 4, 2001, about 1220 Atlantic standard time, a Douglas DC-3A, N19BA, registered to and operated by Roblex Aviation Company, as a Title 14 CFR Part 91 instructional flight, ditched in a shallow lagoon, near Luis Munoz Marin International Airport, San Juan, Puerto Rico, following loss of power in the right engine during a missed approach. Visual meteorological conditions prevailed at the time, and no flight plan was filed. The airplane received minor damage, and the airline transport-rated pilot and commercial-rated copilot were not injured. The flight originated from San Juan, Puerto Rico, the same day, about 1200. The captain stated to FAA inspectors that he was giving flight training to the copilot. As engine power was applied to perform a go-around from an approach to runway 10, the right engine failed. The captain took control of the airplane and performed the emergency procedures for engine failure. While performing the procedures, he noticed the left engine was not producing power. He elected to make a forced landing in the water, 1 mile east of the airport. Just before impact with the water, he feathered the left propeller to avoid a sudden turn during impact. The copilot stated to FAA inspectors that they performed a practice ILS approach to runway 10. The right engine failed and the captain took control of the airplane. While the captain was performing the emergency procedures for the right engine failure, he observed the captain push the left propeller feather button. He had not noticed any malfunction of the left engine prior to this.