The National Transportation Safety Board today determined that the probable cause of the fatal ditching of a commuter airplane off Great Abaco Island, Bahamas, last year was "the in-flight failure of the right engine and the pilot's failure to adequately manage the airplane's performance after the engine failed."
The Board said the engine failure resulted from "inadequate maintenance" that was performed by the operator's maintenance personnel during "undocumented maintenance."
The accident airplane, a Cessna 402C, operated by Air Sunshine, Inc., was on a scheduled flight from Ft. Lauderdale, on July 13, 2003, carrying a pilot and nine passengers, when it experienced a right engine failure and was ditched in the Atlantic Ocean about 7 nautical miles from Treasure Cay Airport. Two passengers (one adult and one child) died after they evacuated the airplane. Five other passengers and the pilot sustained minor injuries and the airplane was substantially damaged.
"This was an egregious and preventable accident that raises many safety issues that need to be addressed," said NTSB Chairman Ellen Engleman Conners. "It also was a clearly survivable accident -- as are most commercial air carrier accidents, and points up the necessity of strictly following time-tested procedures to maximize passenger safety in emergency situations."
The Board found that the right engine failed while the airplane was descending through an altitude of about 3,500 feet. Two or more of the right engine No. 2 cylinder hold- down nuts became loose, which resulted in high-stress fatigue fractures that allowed the cylinder to separate from the engine. The simultaneous loosening of two or more of the cylinder hold-down nuts, the Board said, was due to the "application of insufficient torque" applied by Air Sunshine personnel during maintenance work that was not documented. The Board stated that, at the time of the accident, Air Sunshine's maintenance record-keeping and practices were not adequate.
The Board also found that the pilot had a history of below- average proficiency before the accident flight, including numerous failed FAA flight tests, that contributed to his inability to maintain maximum flight performance to reach land when the right engine was lost.
Additionally, after determining that he was going to ditch the airplane, the pilot failed to conduct a required briefing for the passengers on emergency procedures, including the correct use of personal flotation devices. This failure, the Board said, contributed to passenger fatalities.
Contrary to federal regulations, the pilot also did not have his shoulder harness fastened when the airplane hit the water and, consequently, sustained a head injury that reduced his ability to assist the passengers after the ditching.
Board Members also expressed concern about the role of the Federal Aviation Administration in this accident, noting that although FAA oversight of the air carrier was in accordance with standard guidelines, it was not sufficient to detect maintenance deficiencies at Air Sunshine.
The Board recommended that the FAA issue a bulletin informing inspectors overseeing Part 135 single-pilot operators about the circumstances of the Air Sunshine accident and emphasizing the need for pilots to provide timely emergency briefings.
On a provisional basis, the Board adopted the accident investigation report, subject to revisions to the text and consideration of additional safety recommendations focused on issues of maintenance, pilot proficiency, and regulatory oversight.
A synopsis of the accident investigation report, including the findings, probable cause, and safety recommendation, can be found on the "Publications" page of the Board's web site, www.ntsb.gov.