The second of two space walks planned to replace a faulty cooling pump had to be called after astronauts Douglas Wheelock and Tracy Caldwell Dyson could not get one of the four pressurized ammonia hoses to come off the disabled pump. The crew struggled to get the forth hose loose but had to reconnect it as "A fair amount of ammonia leaked out, forcing them to set aside time to get any traces of the toxic substance off their spacesuits."
Wheelock and Caldwell Dyson where forced to go back to the air lock, to inspect their suits and equipment for ammonia crystals. While none was found, the precautions where necessary, extending the spacewalk to eight hours and three minutes which NASA confirmed was the sixth-longest spacewalk ever.
A third spacewalk is being considered.