I hope I'm reporting this correctly! I was doing a terrible job of trying to power my robots when this crash happened; I think it was adding a gate that did it. I get this crash whenever I try to load this world again.

Time: 11/8/14 7:17 PM
Description: Ticking block entity

java.lang.ArrayIndexOutOfBoundsException: 6
at buildcraft.transport.pipes.PipePowerWood.receiveEnergy(PipePowerWood.java:225)
at buildcraft.transport.TileGenericPipe.receiveEnergy(TileGenericPipe.java:1149)
at buildcraft.transport.gates.GateExpansionPulsar$GateExpansionControllerPulsar.tick(GateExpansionPulsar.java:104)
at buildcraft.transport.Gate.tick(Gate.java:309)
at buildcraft.transport.Pipe.updateEntity(Pipe.java:225)
at buildcraft.transport.pipes.PipePowerWood.updateEntity(PipePowerWood.java:74)
at buildcraft.transport.TileGenericPipe.func_145845_h(TileGenericPipe.java:386)
at net.minecraft.world.World.func_72939_s(World.java:1939)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:636)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:111)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)

You have no idea just how major this bug is. Might have to release a 6.1.8 tomorrow.

Oh right, now I see that I don't have to report this myself. =D
For info on how to easily replicate it, this is what I did to get the crash:

Place down a "Wooden Kinesis Pipe", attach a "Basic Gate" with an installed "Autarchic Pulsar" expansion to it, then set the gate to "Energy Pulsar" or "Single Energy Pulse", then exit the GUI.