The RAF's Inter Services preparations were dealt a blow with a loss away to Chinnor.
They were defeated 29-28 in Oxfordshire with their Inter Services clash with the Army looming next month.
A late Chinnor try was a bitter blow for the RAF who won the Inter Services title in 2018.
The RAF had a tough first half and were behind at the break thanks to tries from Chinnor pair Jacob Hamm and Alex Hunt.
However, Flight Sergeant Justin Coleman's team hit back in the second period.
Will Lamont, Kev Raqio, Rhys Scott Young and Ken Hodgkinson all scored but the RAF were fragile at the back.
They conceded more tries and when Chinnor drove over for a converted try in the final minute, the RAF were beaten.
They have some big games ahead, including the British Police and the French Air Force in Bordeaux, before they clash with the Army at Kingsholm Stadium in Gloucester in March.