Backup wrenches

A fastener backup method, comprising:

• placing at least one fastener engager of a backup wrench arrangement on a respective nut or bolt head of an arrangement of fasteners, wherein the backup wrench arrangement comprises the at least one fastener engager comprising a first engagement surface and a second engagement surface, each of the first and second engagement surfaces configured to engage with a respective face of the nut or bolt head on a fastener when in use, and a reaction torque releasing arrangement for selectively reducing or releasing a reaction torque to enable the backup wrench arrangement to be removed, wherein the at least one fastener engager is configured to automatically allow rotation of the nut or bolt head of the fastener relative to the backup wrench arrangement when the nut or bolt head of the fastener is subjected to a reaction torque above a threshold reaction torque, and wherein the rotation of the nut or bolt head is allowed by a motion of the fastener engager determined by a magnitude of the reaction torque and a force-deflection characteristic of a biasing arrangement acting directly or indirectly on the fastener engager to automatically allow continuous rotation while the reaction torque is greater than the threshold reaction torque;
• disposing a flexible tension element in a channel of the fastener engager or each said fastener engager around the arrangement of fasteners;
• and
• applying a tension to the flexible tension element.