Taking Spares With You
 

I recently noticed a long haul aircraft with a ULD next to it with something like "A340-500 downroute spares & tools. Do not offload"

It got me wondering to what extent spare parts travel on commercial flights....

Simple small and light items that would be easy to replace?
Bigger things that might need a new aircraft to fly them in at great expense?

I've seen spare tyres and loads of cans of oil inside Antonov cargo aircraft.... but it's slightly different when operating worldwide charters I guess.

What about long and short haul pax flights? Or is it pretty rare due to weight/space restrictions?

It's called a fly-away kit. It's more common on long haul flights that I've delt with.

Often carried on charters or other trips to irregular destinations where little or no engineering support is established. Sometimes accompanied by a travelling engineer.

Or three.:}

Once upon a time when the company replaced nearly new aircraft with very old ones, pretty battered ones at that, to save on the leasing payments (same type) maintenance complained about all those flights in learjets they had to do to repair especially hydraulic problems downroute. The company decided to put an hydraulic repair kit on every aircraft consisting of tools and spares, around 120kg in a pretty big metal box latched safely in hold 1. All that for shorthaul 737 flying. Mind you, the engineers had to later mop up what those hired on the spot engineers downroute did to our aircraft. But at least we could fly home most of the time.

In the ad-hoc charter business, many times you do not have a 'home' (expect on paper) so...we carry, as a matter of normal course, 1500KG of spares in our fly-away kit, stowed in the aft belly compartment, and this provides us with good enroute maintenance support, together with our three ground engineers carried.
It works as advertised, no doubt about it.
IE: no cancellations to date, and only minimal maintance delays, otherwise.
Use the six P's...
Prior
Planning
Prevents
Pi**
Poor
Performance.

Properly applied, works like a charm.
Our ground engineers are paid accordingly...and are highly appreciated, especially by the FD crew.
Double for the DFO...yours truly.

Yup, i would think that is not a bad way for a pure charter operation, i think the russkies with their heavy cargo planes operate the same way. We ran scheduled shorthaul stuff with the odd holiday charter sprinkled in, so basically always returning to base.

We carry a substantial fly away kit (corporate jet) and a ground engineer in a suit who is also trained to work on cabin safety for the pax. I'm told one of them mixes a pretty mean martini too!

AWR, to cost the issue, consider the B747 Classic, the wing light lens cover costs a couple of hundred dollars, but if it breaks the aircraft must be flown at M.73/270 KIAS at a reduced altitude if dispatched under the MEL. This can add considerable additional flight time and fuel burn to a flight. So that cheap lens cover ends up costing a substantial amount of money.

Mutt