Where a claim has been filed and is admitted in writing by the personal representative, it shall stand allowed in the absence of fraud or collusion. [C73, §2410; C97, §3340; S13, §3340; C24, 27, 31, 35, 39, § 11961; C46, 50, 54, 58, 62, §635.57; C66, 71, 73, 75, 77, 79, 81, §633.428 ]