Schlumberger Ltd.'s sale of Fairchild Semiconductor to National Semiconductor for $122 million was completed . . . The Investment Company Institute reported that the assets of the nation's 398 money-market mutual funds rose $1.83 billion in the week ended Sept. 16 . . . Shareholders of Wenatchee, Wash.- based Columbia Federal Savings Bank overwhelmingly approved the bank's merger with Washington Mutual Savings Bank of Seattle . . . Westland Aerospace of Britain has been selected to design and produce the wing flap vanes for the new McDonnell Douglas MD-11 tri-jets.