I was on the B(I)8's at Wildenrath, the starter held 3 cartridges and had 3 exhausts. We often had to do single engine starts and we left the engine covers on the other engine. Most of our engine covers had 3 holes which lined up with the starter exhausts. I did it once, starting the LH (No1)engine and looking at the ground crew and feeling for the start button pressed the wrong one. No damage done, the engine covers didn't get sucked in.