I've created a Helicopter, Model and Renderer Works, Entity flies around etc. However I'm trying to have the entity actually drop items onto the ground.

I'm wanting the entity to drop 1 item from a list every 10 seconds.

Is that possible?

 

Absolutely. In your Entity class, override any of the #update related methods, e.g. #onUpdate or #onLivingUpdate, and check:

int time = 10 * 20; // 20 ticks per second times 10 seconds
if (this.ticksExisted % time == (time - 1)) { // if you check against 0, it will drop an item immediately every time the world loads
// drop item
}

Note that if you do create a List of ItemStacks, you will want to drop a COPY of the ItemStack, not the ItemStack itself, otherwise once the first one is picked up, all other drops of that stack will have a stack size of zero.

An item every 10 seconds, by the way, is a lot of items.  If left alone, that would be 30 items littering the ground around one of these entities, constantly, due to the 5 minute entityitem lifespan.

Indeed, what Draco mentions would be a problem, plus your entity will be dropping items very regularly. If you want to add some randomness to it, you can store a long value of the next time the entity should drop an item, and check the current world time against that every so often:

private long nextDrop;

// in onUpdate
if (worldObj.getTotalWorldTime() > nextDrop) {
  if (nextDrop > 0) { // make sure nextDrop has been initialized
     // drop the item
  }
  // set the next drop time
  nextDrop = worldObj.getTotalWorldTime() + rand.nextInt(20 * 60 * 3) + (20 * 60 * 2); // from 2-5 minutes between drops
}

Make sure to write and read the nextDrop value to your entity's NBT data.

You can do this and your entity will spawn items only if a player is within 5 blocks radius, which can be tweaked to your likings:

 

public class YourTileEntity extends TileEntity implements IUpdatePlayerListBox{

@Override
public void update() {
	List<Entity> PlayersInRange = this.worldObj.getEntitiesWithinAABB(EntityPlayer.class, AxisAlignedBB.fromBounds(this.getPos().getX() -5, this.getPos().getY() - 5, this.getPos().getZ() -5, this.getPos().getX() +6, this.getPos().getY() +6, this.getPos().getZ() +6));

	if(!PlayersInRange.isEmpty()){
		System.out.println("Player Found!");
		//Run Code here
	}

}


}

 

EDIT: This Code is for minecraft 1.8, if you are working with an older version you might have to tweak some little things and you don't need to implement IUpdatePlayerListBox

@Cerandior - World#getClosestPlayer is FAR more optimized at finding players than #getEntitiesWithinAABB, an example of which can be seen in the post immediately prior to yours.

@Cerandior - World#getClosestPlayer is FAR more optimized at finding players than #getEntitiesWithinAABB, an example of which can be seen in the post immediately prior to yours.

 

It also is far more cleaner and easier to read. The only reason i posted that code is to give him another option, which he can use in other situations.