I spent my entire service, 9 years, as Shack groundcrew involving many starter crew, engine runs and a not insignificant number of hours as a passenger on detachments. On a periodic medical for offshore work I was warned I could fail the next one due to hearing loss. I applied for a pension and was turned down. On appeal I and my BL helper faced a panel of 6 or 7 people including a lawyer and a medical hearing expert and lost again. The reason given was that once removed from the high noise source no further hearing loss occurs.
The good thing is for the appeal MoD provide you with medical and service records. Had it not been for those records I would never have known I had served in Germany.