Saturday, December 1, 2007
Catastrophic Structural Failure
Focusing on maintenance programs
The airplane originally was manufactured by Grumman in May 1947. At that time, it was certificated as a model G-73 and was equipped with two radial engines. Grumman stopped building the model in 1951. It was designed to carry two pilots and 10 passengers, with a maximum gross weight of 12,750 pounds. Chalk’s Ocean Airways acquired the airplane in 1980. In July 1981, the airplane was modified in accordance with an FAA-approved Supplemental Type Certificate to become a G-73T. The engines were changed to Pratt & Whitney PT6A-34 turbopropeller models, and were equipped with constant-speed, three-blade propellers. The maximum gross weight was increased to 14,000 pounds and additional seats were installed, bringing the passenger seating capacity to 17. On the accident flight, three of the 18 passengers were infants held on the laps of adults. At the time of the accident, the airplane had accumulated 31,226 total flight hours and 39,743 cycles. (A cycle is one complete takeoff and landing sequence.) At the time of the accident, the left engine had 7,515 total hours of which 1,154 were since the last overhaul. The right engine had 9,036 hours with 3,037 since overhaul.
The captain was 37 and held an ATP certificate with ratings for airplane multi-engine land and sea and a type rating for the G-73T. Her first-class medical was current and required her to wear corrective lenses. She had logged 2,820 hours, including 1,630 in the G-73T and 430 as a G-37T pilot in command. She also served as the company’s Director of Safety.
The first officer, 34, held a commercial-pilot certificate and was rated for airplane single-engine and multi-engine land and sea. His first-class medical was current with no limitations. His total time was 1,420 hours with 71 hours in the G-37T.
First to respond to the accident scene were lifeguards who patrolled Miami Beach on foot and jet skis. Most of the wreckage was submerged in about 30 feet of water along a rock jetty. The airplane broke up when it struck the water, and the debris field measured about 200 feet by 200 feet. A Coast Guard helicopter and rescuers were among the personnel to arrive within minutes of Miami’s emergency dispatch center being notified of the accident.
Safety Board investigators interviewed four pilots who were employed by Chalk’s at the time of the accident, one of whom was the husband of the captain on the accident flight. They also interviewed three pilots who had left the company before the accident. The investigators heard that some pilots had concerns about maintenance, including visible cracks, fuel leaks and degraded rivets. One former captain said he experienced two loss-of-engine-power events during flights in 2005 and quit because of his concerns with company maintenance issues. A second pilot told investigators that he also quit because of maintenance concerns and had given the company a five-page letter containing specifics.
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Labels: Accident Statistics, Columns, FAA Regulations, Features, Flight Hazards, Journeys, Maintenance, Safety