The emergency equipment usage load is several times more intense in simulators in comparison with actual aircraft. However most Full Flight Simulators have actual aircraft parts installed in their cockpits: panels, push buttons, switches, Oxygen masks. So, the question comes pretty quickly: do Emergency Equipment is designed for such intense usage in simulators?
Let’s take an actual example: Fire Extinguisher Switch (p/n: D533-05-001) from Boeing 737 Classic simulator. Hopefully they will never be used in actual aircraft, but in a simulator they can be used several times per day.
Few times we had a defect when crew was unable to start up an engine. Fire Extinguishing System is designed to shut off engine if fire extinguisher switch is pulled out. After short investigation we noticed that switch position signal doesn’t change regardless the actual switch position (it is pulled out or not).
Defect reason was very obvious after disassembling of failing switch. Switch position sensing contact plates were broken. As simplified explanation I can summarize that switch didn’t provide the actual position signal to host computer, so computer always saw pulled out switch and won’t let to start-up associated engine.
Keep in mind that switch physically can be pulled out in a single direction with a specific travel distance as designed by manufacturer, however these limitations didn’t prevent against failure. Possibly switch work cycles count was exceeded if there are calculated any.