Yesterday the NTSB held a public meeting to issue the probable cause of a Learjet 60 runway overrun accident on Sept. 19, 2008. Both pilots and two of four passengers were killed when the Learjet, operated by Global Exec Aviation, overran Runway 11 during a rejected takeoff at Columbia Metropolitan Airport in South Carolina. One key issue in the accident was tire pressure. (The other main issue was captain’s execution of a rejected takeoff after V1.) According to the NTSB, the Learjet 60’s tires lose 2 percent of pressure every day. The full inflation of 219 psi drops to 185 psi after eight days and 140 psi after three weeks, the level determined in the accident airplane. During the takeoff sequence, the outboard right tire burst first at 137 knots followed by the other tires, due to excessive flexing of the tires and heat damage caused by underinflation.
At the hearing, the NTSB concluded, “All four main landing gear tires on the airplane were operating while severely underinflated during the takeoff roll, which resulted in the tire failures.” In its conclusion, the NTSB added, “The accident airplane’s insufficient tire air pressure was due to Global Exec Aviation’s inadequate maintenance.” Tire fragments damaged the squat switches, and the logic switched to air mode, which automatically stowed the thrust reversers and resulted in high forward thrust when the pilots were trying to slow the airplane.
Checking tire pressure is “technically simple,” the NTSB stated, but the FAA ...
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