Never had failures in 100+ hours

[SWAFO]

There isn't anything that you're doing wrong, or that's wrong with your copy of FSP. If you fly with a 10% chance of failures, this means that
everytime you fly you've got a 1 in 10 chance of having a failure. If you've flown over 100 hours without a failure, that simply means you've
been lucky! Each flight the percentage is re-calculated, and you have that 1 in 10 chance of a failure. If you'd like a definite failure, try
increasing the chance of it occuring.