Background
On April 1, 2011, about 1635 Atlantic Standard Time, a Cessna 172P, registration N98FR, was on a personal flight from Borinquen, Puerto Rico (BQN) to San Juan, Puerto Rico (SIG). The aircraft was owned by Flight World, Inc. and operated by Isla Grande Flying School under Part 91. Visual meteorological conditions were present, and no flight plan was filed. The private pilot and two passengers were not injured.
Event
According to the pilot, the airplane was cruising at 1,000 feet above ground level when the engine lost power and began to vibrate heavily. Altitude could not be maintained. At about 250 feet, the pilot spotted a runway at a closed, former military base and attempted a landing. During the landing attempt, the airplane struck trees and bushes, resulting in structural damage to the wings and fuselage.
Investigation
An initial examination of the engine by a Federal Aviation Administration inspector revealed that the number 2 cylinder exhaust valve spring was loose. Subsequent examination showed that the exhaust valve, manufactured by Superior Air Parts, had failed. The operator reported that all exhaust valve parts, except for the valve keepers and associated parts, exited the exhaust system. The exhaust valve had accumulated about 1,120 hours since installation.