Army Aviation Engineer - What are they?

Redirects invited as I fear this may venture beyond topic. (I browsed
the FAQ and charter)

My research has come up empty in trying to learn particulars about a
WWII veteran's type of service.

I have a few scattered facts about a grandfather. He was in the Army as
an Aviation Engineer. He was in the 815th. Has a of photo pouring a
runway in Harrington Airfield, England. Served in North Africa and a
lot of Italy. Did communications with morse code and allegedly
preceeded other troops into recently captured territory to help make
usable captured airfields, which may have included bolting together
prefabricated metal runways. (Nat'l Archives had no records)

I would like to learn who this 815th was, what was their role, under
whose command they served, where they went, etc.

-Ryan
.