equator. The Vulcans lacked the range to fly to the Falklands without refuelling several times, as did the converted Victor tankers, so they too had to be refuelled in flight. Eleven tankers were required for two Vulcans, a huge logistical effort as all aircraft had to use the same runway. The aircraft carried either twenty-one bombs internally or two or four Shrike anti-radar missiles externally. Of the five Black Buck raids flown to completion, three were against Stanley Airfield's runway and operational facilities, and the other two were anti-radar missions using Shrike missiles against a Westinghouse AN/TPS-43 long-range 3D radar in the Port Stanley area. Shrikes hit two of the less valuable and rapidly replaced secondary fire control radars, causing minor damage. Withdrawal of the Valiants In July 1964, a Valiant of No. 543 Squadron (WZ394) on a deployment to Rhodesia was found to have cracks in the rear wing spar and was ferried back to the UK for repairs. The following month, a Valiant from No. 232 Operational Conversion Unit (WP217) suffered a wing spar failure during a training exercise over Wales. The whole Valiant fleet was checked, and many were found to have significant cracks in the wing spars. Those that were considered to have little or no damage were cleared to fly, but with a temporary restriction to a maximum speed of , maximum load of , and a maximum bank angle of 30 degrees. When Vickers commenced repairs, it was found that the damage was more severe than first thought, and the entire fleet was grounded on 9 December 1964, and withdrawn from service. At first it was thought that the switch to low-level flying was the cause, but cracks were also found in Valiants that were in service as tanker and strategic reconnaissance aircraft, and had not been flown at low level. Suspicion then fell on the aluminium alloy that had been used, DTD683. One Valiant (XD816) remained in service as a test aircraft, having been re-sparred. Electronic countermeasures and reconnaissance Valiants served in a photo-reconnaissance role with No. 543 Squadron, commencing in the second half of 1955. At least seven Valiants were configured to the ECM role, serving with No. 199 Squadron from 30 September 1957. These aircraft were ultimately fitted with APT-16A and ALT-7 jamming transmitters, Airborne Cigar and Carpet jammers, APR-4 and APR-9 "sniffing" receivers, and chaff dispensers. After the Valiants were