iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad Air 2 (WiFi), released on 2018-04-24T17:07:40Z. The update package is 615.11 MB. This is a delta (partial) update that requires 11.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 448ece6685819800f7f2fd28587e27eed6766aa1.zip.