APU Issues Continue

Shuttle prepares to leave space station, Orlando Sentinel

“Flight rules stipulate that an APU is classified as lost if it is leaking hydrazine or engineers are unsure. The rule is significant because it means stricter weather requirements for Discovery’s landing. In the unlikely event a second APU failed, the shuttle would be forced to land immediately at the next available opportunity. Shannon said the flight rule isn’t applicable to this case because of the slow rate of the leak.”