Specifications 1370light (tn) 91.70length (m) 11.20beam (m) 3.60draught (m) Aircraft Typical Max Landing platform only. No hangar Portuguese Air Force SNIA Alouette II 01 Shipyards A J Inglis - Pointhouse1 Charles Hill and Sons Ltd - Spike Island1 List of Ships Filter: AllPT - Portuguese Navy .......... 1UK - Royal Navy .......... 2 Hide Transfers Hide derivatives 19431949Royal NavyK97HMS AvonMWYT19491970 Portuguese Navy F332 NRP Nuno Trsitão 19431957Royal NavyK253HMS HelmsdaleGGMR2 units Events 1942-jan-01OrderedOrdered K253 HMS Helmsdale 1942-aug-13Laid downLaid down K253 HMS Helmsdale Yard No 1185 1943-jan-08Laid downLaid down K97 HMS Avon Yard No 294. 1943-jun-05LaunchedLaunched K253 HMS Helmsdale 1943-jun-19LaunchedLaunched K97 HMS Avon at Bristol 1943-sep-18CommissionedCommissioned K97 HMS Avon 1943-oct-15CommissionedCommissioned K253 HMS Helmsdale 1946-sep-04TrialsTrials K253 HMS Helmsdale first landing of Sikorsky R-4 on main deck of an RN frigate, near Portland, by Lt Alan Bristow in KK969 of 771 NAS 1949-aprDecommissionedDecommissioned K97 HMS Avon 1949-mayFate: transferedFate: transfered K97 HMS Avon to Marinha Portuguesa 1949-mayCommissionedCommissioned F332 NRP Nuno Trsitão ex RN HMS Avon 1957-nov-14Fate: scrappedFate: scrapped K253 HMS Helmsdale arrived Faslane 7 Nov 1959-jul-25DeploymentDeployment F332 NRP Nuno Trsitão departed Bayonne for Lisbon, with Emperor Haile Selassie of Ethiopia aboard. 1964DeploymentDeployment F332 NRP Nuno Trsitão off Guinea 1970-janDecommissionedDecommissioned F332 NRP Nuno Trsitão 1972Fate: scrappedFate: scrapped F332 NRP Nuno Trsitão at Alhos Verdo, Lisboa