19990427019619A

On April 27, 1999, at 0916 central daylight time, a Cessna 402C, twin engine airplane, N819BW, was destroyed following an inflight breakup during cruise flight and the aircraft descended uncontrolled to the ground. The commercial pilot, sole occupant, received fatal injuries. The Texas charter flight 818 was operated by Texas air charters, denton, Texas, under 14 code of regulations (CFR) part 135 as an on-demand cargo flight from dallas, Texas, to Oklahoma city, Oklahoma. The flight departed dallas at 0816. During interviews, witnesses reported that the airplane was level at approx. 1,000 feet AGL, when the wing departed the aircraft. The aircraft turned right, entered a spiral, and nose dived to the ground. Upon ground impact the airplane bounced into the air approximately 10-12 feet before coming to rest in the wheat field. The wing descended rapidly at first and then slowed and drifted to the ground. Some witnesses reported hearing high revving engine sounds. Witnesses reported that they did not see any other airplanes in the area at the time of the wing separation. Air traffic control data indicated that the airplane was level at 6,000 feet MSL and the pilot had visu sual contact with traffic that was going to pass flight 818. Flight 818 was cleared to descend from 6,000 feet MSL to 4,000 feet MSL. The pilot acknowledged the clearance and that he was beginning the descent. Within a few seconds, radar contact was lost and there were no additional transmissions with flight 818. (-23)on April 27, 1999, at approximately 0918 CDT, a Cessna 402C, N819BW, enroute from dallas love field, Texas to will rogers airport, Oklahoma, was destroyed when it crshed in a wheat field near Goldsby, Oklahoma, after right wing broke off in flight. The failure originated to the right wing lower spar cap in the left side of the right engine nacelle about six inches out board of where the mainlanding gear auxilliary apsr attaches to the main spar. The lower spar cap fracture surface appears to be fatique failure and the fracture surface of the spar web progessing upward about three inches from the spar fap failure has the same appearance. Other fracture surfaces look fresh. The annual inspection was completed pril 6, 1999, at 20404.7 hours total aircraft time. -4)the twin-engine airplane impacted the ground in an uncontrolled descent following the in-flight separation of the right wing during a normal descent. The airplane had accumulated a total time of 20,457 hours and had been flown 52 hours since the most recent annual inspection, which was performed by the current operator 3 weeks prior to the accident. Available maintenance records indicated that since 1988, maintenance personnel had made numerous repairs to the right wing, including repairing skin cracks, working rivets, wing stub spar straps, and the right main landing gear. Metallurgical examination revealed that the right wing's front spar failed due to fatigue that started at an area of mechanical damage and rough machining marks. The presence of primer covering the mechanical damage strongly suggests that the damage was produced during the manufacturing process. It could not be determined whether the mechanical damage or the machining, acting alone, could have caused the fatigue cracking to initiate. Fatigue cracking found on the rear spar and the forward auxiliary spar is most likely secondary fatigue due to load shedding as the crack grew in the front spar.