one reason 5 pod are not used by all operators is that not all B747 are fitted with the mount points inboard of #2 eng
hanging a 5 pod takes under 2 hrs and removing takes slightly less.
having been involved in several this must cheaper as "donor" aircraft can continue as a normal revenue flt albeit with slightly extra fuel burn and restricted flt speed.if your organised then knock down dollys for dead and new eng come in cargo hold of 5th poded a/c in standard cargo bins with tooling etc
in all have received,unhung,rehung new and dead eng back on aog a/c the 5 pod and dispatched in less than 15 hrs (jt9)believe that a cf6 would be quicker due not having to r/r the cascade vanes which you have to swop on jt9
don't see it very often but fun was had whilst doing them