The Junkers F 13 was the world's first all-metal airliner; its impressive characteristic was a corrugated duralumin fuselage. Rebuilding of this "primordial mother" of passenger traffic began in 2009 based on historical construction plans and using the latest surveying technology. Crucial to the success of this prototype was the right mixture of high-precision manual work and the necessary know-how – one of the great strengths at Kaelin.

The airframe of the F 13 alone consists of 2,600 individual parts; its assembly took over 10,000 hours.

35,000 rivets and 60,000 individual parts later the time had come: September 15, 2016 the first hand-built prototype of the "new" F 13 had its maiden flight in Dübendorf, Switzerland. Two years later, and after intensive flight testing, the Swiss aviation authority granted commercial flight approval.

Rebuilding this unique prototype was a very special experience for Kaelin and one of the reasons we are now considered the first port of call for rebuilding.