Preliminary preparations for repair of the Caudron C.59?s horizontal stabilizer and elevators

Suomeksi

The Caudron c.59 (CA-50) airplane’s lower wings, horizontal stabilizer and elevators have been waiting at the Finnish Aviation Museum for the repair work to begin. The restoration of VL Myrsky, continuing for a few more years, and the ongoing repair of helicopter SM-1/Mi-1 rotor blades are still occupying the restoration space, so there is not yet space for the Caudron. However, the preparations for the repair of Caudron’s stabilizer and elevators have been started in another space of the museum.

Before starting the actual repair of Caudron’s wings and tail, a condition assessment was made. Based on the results of the assessment, the principles for the repair work will be decided. The plane will be restored, based on the principles of repairing conservation. This means that the damages will be repaired but everything worth saving will be saved in its original but cleaned appearance.

The condition assessment of the horizontal stabilizer and elevators, still in one piece, took place in late April. The fabric covering of the horizontal stabilizer is in very poor condition. There are several holes and damaged areas in the covering and the fabric has frayed very thin and it breaks like thin paper when it is touched. The fabric covering has almost disappeared on the wooden leading edge of the horizontal stablilizer. It is almost certain that none of the original fabric covering on the horizontal stabilizer can be saved. The covering will have to be dismantled and replaced.

The Tuesday Club team decided to find out how the original covering of the stabilizer has been installed. The original covering principle can be seen clearly through the holes in the rotten fabric. A strip of fabric has been fastened along the ribs of the stabilizer, fastened with another strip of fabric around the ribs. The covering fabric has been sewn onto these strips. Then the covering fabric has been tightened using shrinking dope and painted.

The wooden structure of the horizontal stabilizer has bent crooked during the years, although there are steel wire stiffeners inside. The wooden frame will have to be straightened before the covering work. The wooden frame seems to be undamaged, but the real condition will be discovered when the fabric covering has been dismantled. It is possible that rotten wood will be found under the covering.

The fabric covering on the elevators is in better condition, but fragile. Some of the original covering may be saved, but whether that is possible or not, will be seen later. The covering on the elevators has been fastenede in a similar way as on the horizontal stabilizer and the wooden frame seems intact. There is no wooden batten on the trailing edge of the elevators (and not on the wings, either). The trailing edge looks like a bat’s wing, as in the fabric-covered airplanes built in the 1920’s.

Unfastening the horizontal stabilizer and elevators

The horizontal stabilizer and the elevators are fastened to each other using ten metal hinges. The hinge roots have been embedded in the notches in the stablizer’s trailing edge and the elevators’ leading edge. The hinges have been locked in place using bolts penetrating the stablizer’s trailing edge and the elevators’ leading edge.

The hinge bolts were removed on both sides of the horizontal stabilizer. The nuts on the bolts opened easily although they were rusted, which was quite a surprise as the nuts and bolts have been in place for more than 90 years! When all hinge bolts had been removed, the elevators were pulled away from their hinges. Both elevators could be unfastened easily.

The team decided to unfasten the hinges, still fastened on the trailing edge of the stabilizer, so that they could be cleaned. This would also make the next work phases easier. The bolt of each hinge was unfastened, and the hinges could be pulled out, one by one, from their notches. The hinges were numbered so that it will be easier to install them back into their original places. The last phase was to unfasten the brackets for the upper and lower supporting wires, which are located on the stabilizer’s trailing edge on the third rib.

Caudron C.59’s (CA-50) horizontal stabilizer and elevators are now ready for the actual restoration work to begin.

Photos: Lassi Karivalo

Translation from Finnish to English: Erja Reinikainen.