15 Oct 1941
At 16.24 hours, the boat crash dived after being spotted by HMCS Columbia while shadowing the convoy SC-48 on its port beam. The destroyer obtained no Asdic contact but dropped six depth charges at the diving spot and then remained in the area to keep U-553 down. At 18.15 hours, the U-boat fired its stern torpedo at the destroyer but she managed to evade the attack after a lookout spotted the torpedo track. Running out HMCS Columbia picked up a good contact and delivered an accurate attack with a depth charge pattern, but U-553 had already dived to 55 meters and only received minor damage. In the meantime HMS Gladiolus joined the hunt but carried out no attacks as the U-boat had already crept away. (Sources: KTB U-553/ADM 237-187)

17 Oct 1941
After a successful attack on convoy SC-48, the boat dived to 90 meters when a destroyer approached and dropped three depth charges at the diving position, detonating high above the U-boat which escaped further attacks by passing under the convoy. The destroyer was probably USS Kearny that dropped a single depth charge at 00.22 hours. (Sources: KTB U-553/ADM 237-164)

2 recorded attacks on this boat.