The wing that separated from the Chalk’s Ocean Airways Grumman Turbo Mallard that crashed off Miami Beach last month showed signs of cracking in the main support beam that connected it to the fuselage, according to the NTSB. Although acting NTSB chairman Mark Rosenker stopped short of calling the cracking the sole reason the wing separated from the amphibian shortly after takeoff on the afternoon of December 18, he said a “serious inspection” could have found the defect. The 1947 Mallard G-73T had taken off shortly before 2:40 p.m. for a flight to Bimini in the Bahamas, when only seconds later it broke apart in an inferno and fell into Government Cut channel. All 18 passengers and two crewmembers died in the crash.