[Rules] Crab flail tanks - damage check?

[enrique]

"The British Crab tanks may enter a hex containing a minefield marker in the same manner as an enginner. Following the attempt to clear the mines the British player rolls one die. Add one to the result for each minefield point successfully removed this impulse... On a result of 6 or more the Crab is damaged or destroyed and removed from play. (it does not count as eliminated for victory purposes). On any other result the flail chains are repaired and it may continue to be used"
(BN scenario book, scenario 1, special rule 9).