Frank Bertel Lilliendal is born on 19 May 1919 in Udlejre, Ølstykke, Denmark. He is the son of coach builder Svend Andrew and Maren Cathrine Lilliendal (née Hansen). The father is a natural-born British subject as is therefore Frank Bertil Lilliendal. The family originally arrived in Australia in 1877. 
Volunteers for the Royal Australian Air Force
He enlists for the Royal Australian Air Force on 13 June 1941 at No. 3 Recruitment Centre, in Brisbane. He is re-mustered to Trainee Group V on enlistment with the rank of Aircraftman 1st Class. He is posted to No. 3 Recruit Depot.
At the time of enlistment he has 3 years of previous military experience as Private in No. 42nd Battalion. His civil life occupation is stated as motor and radio mechanic.
On 20 July 1941 he is posted to No. 3 School of Technical Training, Ultimo, NSW. From here he is posted to No. 1 School of Technical Training, Melbourne, VIC, on 9 November 1941. On 1 April 1942 he is posted to No. 2 Squadron, No. 2 Wing, No. 1 Engineering School, Ascot Vale, VIC. From 9 to 10 May 1942 he is admitted to No. 2 RAAF Hospital.
He is discharged on 13 June 1942 from Ascot Vale as medically unfit for further service. 
- Ølstykke parish record, Service record NAA A9301 43086
- Service record NAA A9301 43086