Combined Cycle Journal posted an article yesterday (4/14/11) regarding a potential safety hazard on the 7FA liquid fuel lines – even when the unit is not a duel fuel unit, and fired natural gas only.
A leak around a blank flange on an unused liquid fuel port led to a pressure reduction in the combustion chamber – which allowed the flame to move back and attach to the fuel nozzle itself. Once the flame was attached, severe material deterioration occured.
The details, including pictures and recommendations are included in their article, here. If you operate any 7FA’s – on any fuel – I recommend you take a look at the article’s findings.