An existing crane at Bonneville Dam experienced cracking at some of the member connections.  We were retained by the Army Corps to review the design and determine if the boom was adequate, if the boom had some minor defects that could be strengthened, or if the boom was inadequate and should be replaced.  We found two chords in the main boom and many jib members where the stress exceeded the allowable.  Since the full jib rated load was not needed, we reduced the jib capacity until the overstressed areas were within the allowable stress.