I'm not sure which way the moving parts on the 540 engine rotate - clock or anti clockwise, but if anti then any loose item could have been picked up[ by the fan, alt or belt drive (or the V belts) and been thrown to the lower left with great force. The engines do shed the pot cover screws (big grey ones/ 3 per cap) quite regularly, so if one got loose it could have gone that way with some force if thrown by a belt or fan - see if any are missing towards the back - take the side inspection panel off to check.
h-r
