SilkAir Flight 185

SilkAir Flight 185 was a scheduled international passenger flight operated by a Boeing 737-300 from Soekarno–Hatta International Airport in Jakarta, Indonesia to Changi Airport in Singapore that crashed into the Musi River near Palembang, Sumatra, on 19 December 1997, killing all 97 passengers and seven crew on board.

The cause of the crash was independently investigated by two agencies in two countries: the U.S. National Transportation Safety Board (NTSB) and the Indonesian National Transportation Safety Committee (NTSC). The NTSB, which had jurisdiction based on Boeing's manufacture of the aircraft in the U.S., investigated the crash under lead investigator Greg Feith. Its investigation concluded that the crash was the result of deliberate flight-control inputs "most likely by the captain". While the Indonesian NTSC investigators found "no concrete evidence" to support the pilot suicide allegation, and the previously suspected Parker-Hannifin hydraulic power control unit (PCU) had already been determined by the manufacturer to be defect-free, the final statement from the NTSC was that they were unable to determine a cause of the crash and was thus inconclusive.

Although the NTSB and PCU manufacturer Parker-Hannifin had already determined that the PCU was properly working, and thus not the cause of the crash, a private and independent investigation into the crash for a civil lawsuit tried by jury in Los Angeles County Superior Court, which was not allowed to hear or consider the NTSB's and Parker-Hannifin's conclusions, decided that the crash was caused by a defective servo valve inside the PCU based on forensic findings from an electron microscope, which determined that minute defects within the PCU had caused the rudder hard-over and a subsequent uncontrollable flight and crash. The manufacturer of the aircraft's rudder controls and the families later reached an out-of-court settlement.