National Transportation Safety Board
Office of Public Affairs
Washington, DC - The National Transportation Safety Board today determined that the probable cause of the crash of a seaplane in Miami, FL, in late 2005, was "the failure and separation of the right wing, which resulted from (1) the failure of Chalk's Ocean Airways' maintenance program to identify and properly repair fatigue cracks in the wing, and (2) the failure of the Federal Aviation Administration (FAA) to detect and correct deficiencies in the company's maintenance program."
On December 19, 2005, a Grumman Turbo Mallard (G-73T) amphibious airplane, on a regularly scheduled passenger flight to Bimini, Bahamas, experienced an in-flight separation of its right wing from the fuselage and crashed into the shipping channel adjacent to the Port of Miami shortly after takeoff. Two flight crewmembers and 18 passengers on board were killed; the airplane was destroyed by impact forces.
"This accident tragically illustrates a gap in the safety net with regard to older airplanes," said NTSB Chairman Mark V. Rosenker. "The signs of structural problems were there - but not addressed. And to ignore continuing problems is to court disaster."
The Board found that neither the performance nor the appearance of the airplane would have provided a warning to the flight crew of the right wing's imminent failure. The accident airplane, manufactured in 1947, was operating within its certificated design envelope and carrying normal aerodynamic loads when the wing separated. Preexisting damage to wing structural components would not have been visible to the flight crew prior to departure. There was nothing the crew could have done to regain control of the airplane after the in-flight separation of the wing, the Board said.
The Board noted that the accident airplane had a history of recurring fuel leaks near the area where the right wing separated that were indicators of internal structural damage. Although some repairs were attempted, many were ineffective in that they did not properly restore the load- carrying capability of the wing structure. The failure of Chalk's to identify and properly repair fatigue cracks in the wing, and the numerous maintenance-related problems found on the accident airplane and another company airplane, demonstrated that Chalk's maintenance program was inadequate to maintain the structural integrity of the company's fleet, the Board said.
The Board also noted that because of the limited availability of engineering services and manufacturer support for the G-73T Mallards, effective FAA oversight was important to maintain the airworthiness of these older airplanes. Although FAA oversight was performed in accordance with existing federal regulations, the Board said, it did not result in the detection and correction of the systemic deficiencies in Chalk's maintenance program and, therefore, was insufficient to ensure the safety of the airline's operations.
As a result of the investigation, the Board issued two new safety recommendations calling on the FAA to: verify that airline maintenance programs include stringent criteria to address recurring or systemic problems, if necessary through comprehensive engineering evaluations; and, to modify procedures for oversight of maintenance programs of carriers like Chalk's to ensure the continued airworthiness of the operator's fleet.
Earlier in the investigation, concerns were raised about federal regulations that exempt airplanes like the accident airplane, that were type-certificated before January 1, 1958, from a requirement for more rigorous damage tolerance- based supplemental inspections. Consequently, on July 24, 2006, the NTSB issued a recommendation (A-06-52) urging the FAA to eliminate the exemption for these older airplanes.
As the FAA has indicated that it intends to address the identification of age-related problems for older airplanes through current operational safety programs, the Board has classified this recommendation as "Open-Unacceptable Response."
"Does it make sense," said Chairman Rosenker, "that rules designed to deal with the problems of airplanes as they age would exclude the oldest ones in the inventory?"
A synopsis of the Board's report, including the probable cause and safety recommendations, is available on the NTSB website, www.ntsb.gov, under "Board Meetings." The full report will be available on the website in several weeks.
NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.