The repair of the Caravelle III (SE-DAF) radome has been started

Suomeksi

The Caravelle III, owned and brought from Sweden by Aviation Museum Society Finland, is stored in a hall in Pansio port area near Turku. There it is being restored before placing it on display at Turku airport. In Turku the local volunteer team is working on the restoration, which started with cleaning the aircraft’s surfaces before painting. The Tuesday Club has been given the task to repair the damages which have been caused on the aircraft during its long storage period. There is damage on e.g. the right wing-tip, the left tip of the horizontal stabilizer and the radome on the aircraft’s nose. We just can’t help wondering which airport vehicle at Arlanda has managed to bump into the Caravelle so many times.

Annoyingly, the damage caused by the collision on the radome happens to be right on one of the hatches which cover the fastening bolts of the radome. The radome, made of glass fibre, has bent inwards at an area of about 20x15 cm. The collision has also broken the edge ring of the radome and damaged the rim of the bulkhead on the aircraft’s nose, under the radome. There is also damage on the aircraft’s nose under the bulkhead edge, the metal edge of the nose is bent, and the aluminium covering is creased. The painted surface of the glass fibre radome is also badly flaking.

The Turku team disassembled the damaged tips of the right wing and the left horizontal stabilizer and the nose bulkhead, with its radar and radome. We fetched the bulkhead and the tips of the wing and horizontal stabilizer from Pansio to be repaired at the Finnish Aviation Museum in Vantaa. The repair of the radome and the wing tip are well under way, the tip of the stabilizer will be repaired later.

Before repairing the radome, it had to be disassembled from the nose bulkhead. The radome is fastened on the bulkhead rim with three fastening bolts and three guide pins. The bolts can be seen when the hatches on the radome, one above each bolt, are opened.

First the hatches above the two unbroken fastening bolts were opened. Under each hatch a supporting frame could be seen, it is fastened on the radome glass fibre and on the radome’s metal edge. There is a crown-headed fastening bolt in the middle of the frame. The two bolts on the edge could be easily opened and unfastened from the threaded sleeve on the metal rim of the bulkhead. Fortunately also the bolt under the damaged hatch could be opened and after this the radome could be lifted from the bulkhead. We could now see that the radar space under the radome was empty. The radar had been disassembled at some point during the Caravelle’s storing period, but obviously before the radome was damaged.

When the radome had been disassembled, we could see the damage on the bulkhead’s metal rim, under the radome’s edge. The bulkhead rim is badly bent inwards and broken. It must be repaired before the radome can be assembled back into its place after repair.

Photo: Reijo Siirtola

As a preparatory task before repairing the glass fibre radome, the damaged metal frame of the fastening bolt was disassembled. The metal frame has been tightly riveted on the damaged edge of the radome, we didn’t even try to unfasten it in other ways than just by cutting through the radome’s metal edge on either side of the bolt’s frame. The broken area of the radome could now be removed together with the bolt frame.

Photo: Reijo Siirtola.

The repair plan is to first build a replacing piece for the removed section of the radome’s metal edge. The broken metal frame for the bolt can’t be used any more, so we came up with a solution where a bridge between the radome’s cut edges will be made from strong plywood. The third radome bolt can be fastened on the threaded sleeve on the bulkhead’s rim through the plywood bridge. A metal collar for the bolt will be inserted on the hole on the plywood. This repaired joint of the third bolt will not be as strong as the original, but it will be quite ok for the radome of a non-flying display aircraft. From outside the difference won’t be seen.

Photo: Reijo Siirtola.

When the radome’s cut edge has been repaired in the way described above, a sufficient number of glass fibre fabric layers will be laminated with epoxy resin on the collision hole on the radome. The laminated area will be ground to match the level of the dome’s original surface. A hole for the bolt hatch will be made into the laminated surface.

We started to build the piece missing from the radome’s metal edge. A piece of strong plywood was cut, imitating the shape of the missing edge piece. The piece of plywood was glued with epoxy glue as a bridge between the ends of the metal edge. There is still some work needed before the bridge is ready. After that we will laminate the hole in the radome. The edges of the damaged area in the glass fibre dome have already been ground thin for the laminating work.

Photos by Lassi Karivalo except if otherwise mentioned.

Translation by Erja Reinikainen.