Here is an Angry Birds Rio Apple Guide that will help you find all the hidden apples in Airfield Chase. The location of the apple is marked with a red box.
Apple 1: Level 9-1
Zoom out first so you can see a labeled bush behind the bird platform. The apple is hidden in the bush. Shoot the birds backward and try to hit the bush to get the golden apple.
Apple 2: Level 9-2
In this level it is very easy to get the hidden apple. In front of the bird platform is a labeled bush. Hit the bush with any bird to get the fruit.
Apple 3: Level 9-5
The golden apple is under the birds platform. The apple in this level is not really hidden. Use the Big Brother Bird and bounce it on the rock and into the TNT crates to get the fruit.
Apple 4: Level 9-6
The golden apple is in the labeled crate next to the three apples. Use any bird to smash the box and get the fruit.
Apple 5: Level 9-9
In this level, the fruit is hidden inside the labeled oil barrel next to the gasoline can. You can get the fruit by hitting the barrel directly or hit the blue gasoline can next to eat with an egg. the explosion will smash the barrel.
Apple 6: Level 9-10
The golden apple is hidden in the labeled luggage. Use the yellow bird to smash the wooden blocks and get to the labeled luggage.
Apple 7: Level 9-14
The apple is hidden in the labeled bush on the right side of the screen. Clear some of the structures first so you will have a better shot at hitting the bush. Here’s how.
Apple 8: Level
To get the golden apple smash the labeled boulder in front of the bird platform. Use the black bird to get the fruit.
Apple 9: Level 10-4
The golden apple is hidden inside the labeled suitcase located on the right side of the screen. First take down the middle structure so you have a clear path to the luggage. You can use Blu and a yellow bird to do this. Then use another yellow bird to hit the horizontal wooden block to smash it. This will cause the other structures to fall on the luggage and smash it open.
Apple 10: Level 10-7
The golden apple is in the oil drum just in front of the bird platform. Use any bird to smash the oil drum and get the fruit.
Apple 11: Level 10-8
In front of the slingshot is a labeled bush. Launch Big Brother bird on the bush to get the fruit.
Apple 12: Level 10-10
The golden apple is hidden inside the labeled crate just beneath the birds platform. The crate has 3 apples on top of it to give you a better picture. Use the white bird and drop the egg just on top of the crate to get the food.
Apple 13: Level 10-12
The golden apple in this level is hidden inside the labeled barel in the middle of the screen. Clear the structures first to have a clear shot of the barrel. Watch the walkthrough video to see how.
Apple 14: Level 10-14
There’s a labeled bush just beneath the lights of the bird platform. The white bird is the only bird that can hit the bush using the egg bomb. Time your tap to drop the egg bomb on the bush. You will be able to get the fruit.
Apple 15: Level 10-15
Look closely at the wing of the plane. You can see that it’s labeled. Use the yellow bird to hit the labeled part and get the fruit. Here’s how.
You can watch the Angry Birds Rio Apple Walkthrough here.