Can't get this macro to work. Has something to do with the way I'm listing
the values but I don't know how to do this properly. Also, I need to be able
to list over 60 values (not just the 3 shown below), i just truncated for
this post. Please help!!!

Sub CheckNNumbers()
Dim RowNdx As Long
Dim LastRow As Long
StartRow = 2
LastRow = ActiveSheet.UsedRange.Rows.Count
For RowNdx = LastRow To 1 Step -1
If Cells(RowNdx, "R").Value = "N117CH" Or "N917SH" Or "N911WK" Then
MsgBox "Invalid Aircraft No."
End If
Next RowNdx
End Sub

Again, I just need to know how to "list" multiple values. I've tried using
commas in place of the "Or" statements but nothing works! Please help!!!