We'll now use some of the techniques we have learnt from the fuselage and tail to weather the engines slightly.

To start with lets have a quick look at the engines again:

To start with we'll add a few grime streaks, the line I've chosen to create the streaks along is where the engine cowling slides backwards whilst the engine is creating reverse thrust. This is quite a common area for dirt to appear, most likely due to the way dirt collects along deep joins and is then blown backwards by the forward motion.

Add a new layer and select the Brush Tool (B), set your active colour as black and your brush size at around 5 pixels.

Dot a few blobs of black along the panel.

Select the Smudge Tool (R) and set the brush size to around 5 pixels.

As before, place the cursor at the blob. Click and hold the mouse button, drag the mouse in the opposite direction to travel, arch the smudge appropriately (in this case downwards).

Use the following image as reference:

In order to create a subtle effect we'll set the layer opacity to about 10%.

Repeat the above process on separate layers until you have covered the area as desired.

In the above image you can see I've curved the streaks upwards, if you imagine the shape of the engine, the streaks on the lower part will actually angle upwards as the air flows over it. Similarly, the below image shows the streak in the middle to be straight, this too is due to the way the air flows over it.

Each time set the layer opacity to a similar amount, however for certain instances differing opacity settings may be appropriate.

Here you can see the completed panel line streaks.

We'll now add a bit of dirt to the engine pylons.

Once again select the Brush Tool (B), set your active colour to black and the brush size to around 5 pixels.

Add a new layer and paint some rough lines and blobs around areas you want the weathering to occur.

Select the Smudge Tool (R) and set the brush size to around 5 pixels.

Place the cursor over an area of the black, click and drag the cursor along the area. Every now and then flick the cursor upwards to create an erratic effect.

Set the layer opacity to about 10% to once again achieve a subtle result.

Feel free to add further effects which you have learnt from the fuselage and tail weather sections.

Be careful when dealing with pieces of texture that are mapped to two different areas. For example, there are two engine pylon textures on the sheet but of course in total there should be four pylon textures. The model creator has shared each of the pylon textures to do different areas. When adding weathering and highlight effects keep in mind the effects will be duplicated across two different sides so may cause a repetitive look.

We'll now move on and have a brief look at the wings.