I believe the hole is to let any accumulated oil/fuel to drain, the only thing I would worry about is the remaining piece of aluminum breaking off in the future, it looks like it's already broke at the bottom. I would stuff paper towels in it and pretend you're pulling a tooth with a pair of channelocks, and you don't buy a case half, they are a matched set. I'm a 787 guy but basically the same as far as this is concerned I believe. Lee