Any association may continue to recognize the authority of an attorney in fact authorized in writing to manage or to make withdrawals either in whole or in part from the savings account of a member or savings account holder until it receives written notice or is on actual notice of the revocation of his authority. For the purposes of this section, written notice of the death or adjudication of incompetency of such savings account holder shall constitute written notice of revocation of the authority of his attorney. No such institution shall be liable for damages, penalty or tax by reason of any payment made in accord with this section.