Can anyone guess how long it took for the sim to crash?
Last time I used the Helisim IOS, a fire on its own would not have caused a crash - but maybe it's changed? Regardless, real world fires can be very fierce and cause catastrophic damge very quickly, as this example shows:
http://www.aaib.gov.uk/cms_resources...pdf_503163.pdf
I believe the MGB was collapsing through the roof within 3 minutes of the initial warning, but others here will be nearer the detailed facts I'm sure.