iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad Air 2 (WiFi), released on 2018-04-24T17:07:41Z. The update package is 31.42 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4c00b5ba33a61ccc3ee89165b51f79ddbec7aacc.zip.