Original: They are typically specified to withstand an impact of 3400 g and temperatures of over 1,000 Â C (1,832 Â F) (as required by EUROCAE ED-112).
Simplified: They are usually built to withstand an impact of 3600 g and temperatures of over 1,000 Â C (as required by EUROCAE ED-112), because a powerful impact followed by a very hot fire is what usually happens in a plane crash.