In June 2016, defence chiefs stated that the Northrop Grumman intercooler could not cope with the warm waters of the Gulf. The manufacturers, Rolls-Royce, said that while the engines for the WR-21 had been built as specified by the Ministry of Defence, the conditions in the Middle East were not "in line with the specs of the intercooler". The First Sea Lord, Admiral Philip Jones, clarified that the "WR-21 gas turbines were designed in extreme hot weather conditions to what we call ‘gracefully degrade’ in their performance, until you get to the point where it goes beyond the temperature at which they would operate... we found that the resilience of the diesel generators and the WR-21 in the ship at the moment was not degrading gracefully; it was degrading catastrophically, so that is what we have had to address".