Studs and Inlets Fail After Script Is Ran?

So here is a a script I made (yes, I finally managed to do something :D) that is supposed to make Plane be anchored when it is cloned, which it does, and then in 10 seconds, it is supposed to unanchor. I have the BaseParts that are welded together using studs and inlets. In-game, the plane falls apart mid-air. Why is this and how can I make it fall as one piece because I thought studs and inlets would keep it together.

for _,v in pairs (game.Workspace.Plane:GetChildren()) do
if v:IsA("Part") or v:IsA("BasePart") or v:IsA("UnionOperation") then
    v.Anchored = true
    end
end

wait(10)
for _,v in pairs (game.Workspace.Plane:GetChildren()) do
if v:IsA("Part") or v:IsA("BasePart") or v:IsA("UnionOperation") then
    v.Anchored = false
    end
end
wait(4)
for _,v in pairs (game.Workspace.Plane:GetChildren()) do
if v:IsA("Seat") then
    v:Destroy()
    end
end