A flag is a potential hazard that, if left unresolved for longer than the next scheduled inspection, could result in collapse of a beam, or even a bridge.
The scheduled inspection on 18 February 2007 had not taken place and the faults had gone undetected.
The station keeper was showing it to the shift commander, Lieutenant Flood, right before a scheduled inspection, when it exploded.
It is common for engines to operate for tens of thousands of hours without difficulty before being removed from service for a scheduled inspection.
"We did the regular scheduled inspections," Carey said.
"One more scheduled inspection, a fill-up at the Marble Point fuel dump, and I think we'll be all right to head into the valleys."
The maintenance telltales by the egress hatches on module eighteen showed that nothing had been opened since the last scheduled inspection.
Time-based maintenance is labor intensive, ineffective in identifying problems that develop between scheduled inspections, and is not cost-effective.
Everyone is looking forward to our scheduled inspection and repair detail at Star Base 11, and most of the crew have requested leave.
Under a red flag, a structural failure is expected to occur before the next scheduled inspection.