Mobile Phones in the cockpit.
Have been told by an experienced EC135 HEMS pilot that one day while doing his A check his fone rang while he was bent over an engine, suddenly the igniters went off, even with the aircraft battery switched OFF. Luckily there was no fuel in the engine or he could have got an unexpected sun-tan. It's now company policy to ensure all fones must be switched off in the helicopter at all times.
Regards,
BC.