Stds Doc14 version 6 (Sept 2012) Para 4.5
"If a type or class rating has expired by more than three years....examiner cannot sign the cert. of revalidation...application must be submitted to CAA.."
IN-2014/109
Para 2.1 "The previously advised restriction that examiners must not sign the renewal/revalidation page of the licence if the relevant privilege expired more than three years.."