Deer Valley Airport, linked to Phoenix International Airport in Arizona, has recently seen a number of changes as it adapts to increasing demand. As part of this development programme, general contractor Kiewit was chosen to build a new air control tower. Kiewit hired local crane hire firm Southwest Industrial Rigging to lift the top piece of the tower into place.
A Southwest Grove GMK 7550 mounting the top of the new control tower at Deer Valley airport
Engineers working on the tower warned Southwest that the tower top could collapse under its own compressive forces put onto it by the slings, so a 50ft minimum sling length was chosen.
Initial estimates put the load at around 60,000lb (27t) Southwest chose to use a GMK 7550 with Mega Wing boom bracing, and 87,000lb capacity. When the lift was carried out, the load was found to only be 55,000lbs, giving an extra safety margin. The tower top had to be lifted over 100ft (32m)high, to a radius of 70ft. As wind was an issue, the lift began early in the morning.
