Unexpected colour patch! Please help.

[abhijit]

Two days ago suddenly I saw a colour patch like sunburn in the front side of two leaves of my Aerides fieldingii. But when I saw the back side the picture was quite deferent. I have no idea about this. Is it a symptom of sunburn or fungal effect or bacterial attack or.....?
Please help me what can I do for her. Here I attach front & backside photographs.

[Discus]

If the patch is wet, it may be bacterial, but it's more likely to be fungal; you'd need something systemic to treat it.
To be honest, if I see something like this on a leaf, I usually cut it off and seal the cut end, kind of like sawing your leg off to stop the zombie bite taking you over!

[RosieC]

Could this be sunburn?

Sunburn can allow other infections an entry point but may not be a further problem in it's own right.

[WhiteRabbit]

My first thought is also sunburn

[tucker85]

Looks like sunburn to me.

[King_of_orchid_growing:)]

Sunburn.

[NYCorchidman]

sunburn. They both look dry too.

[RosieC]

If it's sunburn (as others seem to agree) then you don't need to remove the leaf unless you see something spreading from the patches. They won't colour back up again but will likely just stay like that without causing a problem.

Obviously if sun-burn check your light levels to avoid it happening again.