Spare parts are a type of currency in Avatar: Frontiers of Pandora and it's used to buy weapons, armor, and other useful items from the traders at the Resistance Headquarters. You'll need to stockpile quite a lot if you want to buy some of the bigger items on offer, so it's worth knowing the best way to get hold of it.
Once you find Nor early on in the main story, the game will open up significantly, and you'll be free to explore the world of Pandora. It's also worth noting that Clan Favor is also used as a currency later on if you prefer the Na'vi fighting style, but if you've got your heart set on more of an RDA loadout, here's how to find spare parts on Pandora.
Where to find spare parts
As spare parts are basically man-made and aren't a natural part of Pandora, your best bet for finding them is to search RDA outposts or facilities. You'll come across a couple of these early on as part of the story, so you should look out for the brightly coloured crates—most commonly yellow—dotted around these places.
These containers often contain other useful items such as weapon or armor mods or RDA rations, so searching RDA outposts thoroughly whenever you come across them is worthwhile. Just make sure you've got enough food so your health refills, and it's a good idea to have a full stock of Dapophet pods too, in case you need emergency healing.
Once you get to the point where you can start exploring Pandora with relative freedom, you'll often find RDA facilities marked on the map as you get close so these are well worth investigating. Using your Na'vi senses as you explore, and listening for distant gunfire is also another way of pinpointing the location of RDA members—they often get into fights with the local wildlife and this generally means there's some kind of base nearby.
You can also increase your yield by learning Scavenging Expert on the Maker skill tree. This means that you can sometimes find spare parts when looting AMPs, and as RDA bases generally have two or three of these stomping around, this can be pretty handy.