Thanks guys, so that's how I tought it was...I might see what I can do out of it.
I think that with light Armor+Bd+Wh/mech-steed with a 4+save the pigeon is less treatening to the engineer and theirs also the WP prayers to help restore would and give 4+ ward save.There's only 1/6 chance that you hit yourself, 2/3 to wound, 1/3 you save and you have another wound left so it's not SO bad...
I feel like I could find some use to it, with war machine crews place the crews far away enough from the engineer and with the cav. base it's easy to avoid hitting the crews.
I think that against armies that have good war machine hunters the engineer should go with cav. or infantry units.The way to use him is to load him with most of his weapons so you can/must use the right one every turn.
Desperatly trying to find the best way to use him as an all-round character...without let him home that is.