On 19 December 2005, a Grumman Turbo Mallard Sea Plane suffered a loss of control following the in-flight separation of the right hand wing, Miami Port, Florida, USA.
This dramatic and fatal example of structural fatigue involved a 58 year old Grumman G73T Turbo Mallard Seaplane, which shed the complete right hand wing when the main spar failed. The investigation found that the right wing separated from the airplane because of multiple pre-existing fatigue fractures and cracks, which reduced the residual strength of the wing structure.
The following is the Executive Summary from the official NTSB report (AAR-07/04):
"On December 19, 2005, about 1439 eastern standard time, a Grumman Turbo Mallard (G-73T) amphibious airplane, N2969, operated by Flying Boat, Inc., doing business as Chalk’s Ocean Airways flight 101, crashed into a shipping channel adjacent to the Port of Miami, Florida, shortly after takeoff from the Miami Seaplane Base. Flight 101 was a regularly scheduled passenger flight to Bimini, Bahamas, with 2 flight crew members and 18 passengers on board. The airplane’s right wing separated during flight. All 20 people aboard the airplane were killed, and the airplane was destroyed by impact forces. Flight 101 was operating under the provisions of 14 Code of Federal Regulations Part 121 on a visual flight rules flight plan. Visual meteorological conditions prevailed at the time of the accident.
The National Transportation Safety Board determines that the probable cause of this accident was the in-flight failure and separation of the right wing during normal flight, which resulted from (1) the failure of the Chalk’s Ocean Airways maintenance program to identify and properly repair fatigue cracks in the right wing and (2) the failure of the Federal Aviation Administration (FAA) to detect and correct deficiencies in the company’s maintenance program.
The safety issues discussed in this report focus on air carrier maintenance programs and practices and FAA oversight procedures for air carrier maintenance programs. Safety recommendations concerning these issues are addressed to the FAA."
For further information, see the official NTSB Aircraft Accident Report: AAR-07/04