The reparation work on the Super Chug wing is under way

Maanantai 2.3.2026 - Tuesday Club member

Suomeksi

The wing of Super Chug (OH-XTM Super Sytky) remained almost intact in the landing accident in August 2024. However, a large area of the covering plywood at the root of the left wing's underside was damaged. The damage occurred when the landing gear folded beneath the fuselage, causing the left wheel of the gear to strike the underside of the wing and break the plywood covering. A small hole appeared on the upper surface of the right wing's trailing edge, and there were a few cracks in the plywood edges of the trailing edge. Otherwise, the wing surfaces are intact.

Photo: Timo Kopranen

So far, the Super Chug wing has been stored in our sea container outside our Puusepäntie workshop, waiting for the repair work to begin. The start has been delayed by the question of whether the wing would fit in the workshop among the fuselages of Super Chug, Snoopy and Myrsky MY-5, which are already there. The Super Chug wing is a single piece with a wingspan of 5,3 metres.

We measured the workshop space and concluded that the wing could indeed fit between the fuselages of Super Chug and Snoopy, placed on wing stands, if we move the fuselages of Snoopy and MY-5 about a metre sideways. However, when placed horizontally, the wing would not fit between the fuselages of Chug and Snoopy.

Photo: Timo Kopranen

Once the fuselages had been moved, we carried the Super Chug wing from the storage container into the workshop. There, the wing was placed on wing stands. Surprisingly, there was still plenty of working space around the wing. We set the wing on the stands in a slanted position so that the more severely damaged underside of the wing was well exposed, making it easier to repair.

The damage caused by the landing gear wheel striking the underside of the wing will be repaired by removing the plywood covering from the damaged area, rebuilding the inner wing structures destroyed in the accident, and finally re-covering the opening.

To remove the damaged plywood area, a rectangle was drawn around the damage so that the damaged section was well within the rectangle. The plywood was then cut away along the outline of the rectangle using a multitool blade.

Underneath the plywood an area of about 40 x 60 cm was exposed, damaged from the wing spar towards the trailing edge. Of the three ribs in the damaged area, two had broken. The covering plywood left on the surface of the intact rib during sawing was carefully tapped off with a chisel.

Now we were also able to examine the structure of the wing. It turned out that the Super Chug’s wing ribs are not of the “traditional” type with lightening holes and cap strips. Instead, the Chug’s wing rib consists of a rib edge plywood, reinforced with a cap strip, to which a lattice of thin strips had been glued. The plastic tubes for the pitot tube, which run inside the wing and are attached to the ribs, were now visible too. The pitot tube, which was removed from Super Chug’s wing after the accident, has a horn-like appearance and points directly downwards. It is similar, for example, to the non-heated pitot tube of the Piper PA-28 Cherokee.

The broken wing ribs in the damaged area were dismantled so that new ribs could be constructed to replace them. At the same time, patching the small hole at the trailing edge of the right wing was started. In this case as well, a rectangle was drawn around the hole, and an opening was cut in the plywood accordingly. Plywood strips were glued under the edges of the opening so that they extended about half a centimetre inside the opening. A plywood patch was shaped to fit snugly into the opening. It will be glued in place to cover the hole. The seams of the plywood patch will be filled and sanded smooth before painting the patched area. A couple of cracks in the plywood edges at the trailing edge were also glued. The work to repair the wing of Super Chug OH-XTM has got off to a good start.

Photos: Lassi karivalo, unless otherwise mentioned

Translation to English: Erja Reinikainen

The Super Chug´s landing gear attachment frames are repaired

Tiistai 13.1.2026 - Tuesday Club member

Suomeksi

Repair work on the damaged PIK-21 Super Chug (OH-XTM) continues in the Tuesday Club at the Puusepäntie workshop. One of the areas being repaired is the damaged double fuselage frame, located between the cockpit and the firewall. These frames are the front and rear attachment frames for the landing gear, to the lower ends of which the undercarriage is attached. Furthermore, the frames ensure that the nose of the aircraft keeps its shape. The rudder pedals are also attached to the bottom rail of the front attachment frame for the undercarriage. For the rudder pedal cables there is an opening in the lower part of the rear frame.

In the crash of the OH-XTM in August 2024, the undercarriage collapsed and folded under the fuselage, severely damaging the lower section of the aircraft’s nose. At the same time, the lower halves of both undercarriage attachment frames were broken, all the way up to the mid-point of the frames. The upper parts of the frames remained intact. The rudder pedals were still attached on the broken lower sections of the undercarriage frame pair.

When considering how to repair the fuselage frame pair, we decided that it was not necessary to rebuild the entire pair. This way, we avoid having to dismantle and rebuild the intact upper parts of the frames, and the entire area between the cockpit and the firewall. The undercarriage attachment frames will be repaired by reconstructing the destroyed lower parts and joining them to the upper parts that have remained undamaged. We can proceed in this way because we are not making OH-XTM airworthy but rather restoring it to become an exhibition piece.

To join the new reconstructed lower sections of the double frames to the intact upper parts, the stubs of the frames were trimmed to equal length. On each side of the frame stubs the 2 mm thick plywood on the sides, supporting the frame, was removed for about five centimetres in preparation for the upcoming new joint.

Fortunately we have access to the original Super Chug drawings, made by Kai Mellén, which provide precise details of the frame structure and the materials required for their construction. Moreover, our work is made easier by the fact that the frame drawings are at a 1:1 scale, allowing us to build the damaged lower section of the frame and check its shape directly on top of the drawing when the work is under way.

To obtain the material needed for the construction, pine strips measuring 12x12 mm and 12x40 mm were sawn according to the material list specified in the drawings. The wood for sawing was obtained from the Myrsky restoration project, so it is dense-grained and of so-called aircraft quality. We also have at our disposal some 2 mm thick aircraft plywood, also left over from the Myrsky project, to be glued on both sides of the new fuselage frame piece for support.

We began constructing the lower parts of both attachment frames simultaneously. We made all the necessary components for building the frames. Once all the parts were ready, they were glued together to form the lower half of each fuselage frame. We used Casco Outdoor wood glue for the work. The glued lower sections of the frames were then sanded with a disc sander. An opening, as shown in the drawings, was made in the rear frame’s bottom rail to allow the rudder pedal cables to pass through.

Both lower sections of the frames were made slightly too long at the top. This gave us some leeway for making the joints, ensuring that the new undercarriage attachment frames would match the drawings exactly in size. We placed each lower section we had built on top of their respective drawings. They matched their drawings well. The following step will be to join the newly constructed lower sections of the undercarriage attachment frames to the original undamaged upper parts.

Photos: Lassi Karivalo

Translation to English: Erja Reinikainen

The repairs on the Super Chug fuselage under way

Keskiviikko 19.11.2025 - Tuesday Club member

Suomeksi

The repairs on the Super Chug OH-XTM, which was involved in a serious landing accident, have started. The first target will be the damaged fuselage of the aircraft. The lower part has been damaged between the rear section of the cockpit area and the firewall. The firewall is the rear section of the nose part, covered with a metal plate on the outer surface for fire protection. The lower part of the fuselage has been completely destroyed to the floor level, and the covering plywood on both sides is partly tattered halfway up the fuselage. The rear fuselage remained intact in the crash.

The fuselage between the cockpit and the firewall of the OH-XTM was laid ”inverted” to facilitate repairs.

To start the repairs on the wooden fuselage, which had been stripped of the engine, the front section of the fuselage was emptied of all the wires and gadgets. First the fuel tank, which filled the front section of the fuselage, had to be removed to gain access to the wires and tubes leading from the cockpit to the engine bay. The fuel tank fastening straps were opened, after which the tank was lifted out of the front section of the fuselage. The tank straps were left in place for the time being.

After the fuel tank had been removed, the wires and cables going through the firewall from the cockpit to the engine bay were detached from their holders and the wires were pulled through the firewall. To completely empty the front section of the fuselage, we had to detach the rudder pedals, which were attached to the broken front fuselage former, and the wires leading from the pedals to the rudder.

Photo: Jouni Ripatti

When the aircraft hit the ground, the firewall was mostly torn loose from its fuselage joint and simultaneously it was damaged at the edges. It had to be taken out for repairs. The firewall and fuselage joint seam was sawn open, using a multi-tool saw blade, to cut loose the part that was still hanging to the fuselage. Thus the firewall could be detached from the fuselage for repairs and the space between the cockpit and firewall opened, apart from the fuel tank straps.

Photoa: Ari Aho

As to the fuselage side damaged covering plywood sheets, it was established that the repairing would be better done by covering anew the side areas with plywood. Thus the damaged areas of plywood were sawn off with the saw blade of the multi-tool. The plywood was sawn along the fuselage stringers so that about 10 mm of plywood was left outside the edge as a rabbet for the future butt joint. A 20 mm high wooden batten will be glued on the fuselage stringer as a support for the butt joint where the edges of the old and new plywood join.

Photos: Lassi Karivalo, unless otherwise mentioned

ranslation to English: Matti Liuskallio

OH-XTM Super Chug fuselage ready for repairs

Lauantai 18.10.2025 - Tuesday Club member

Suomeksi

After the Super Chug fuselage had been moved to the Puusepäntie workhop, the preparations to restore the damaged fuselage began. The first task was to detach the engine from the fuselage, because handling the damaged fuselage with the heavy engine in place would be nearly impossible.

Photo: Matti Kainulainen

So we started to detach the Super Chug’s VW 1600 engine from the fuselage together with the engine mounting. In doing so we’ll avoid detaching the wires, tubes and engine equipment within the engine mounting frame.

Photo: Jouni Ripatti

The engine mounting was attached to the fuselage with five bolts. We tried to open the nuts of the bolts that penetrated the firewall. The bolts, however, turned simultaneously when the nuts were turned. Somehow, we had to gain access to the bolt heads behind the firewall. If the nose of the aircraft were intact, gaining access to the bolts would be almost impossible, because the bolts were situated behind the fuel tank between the cockpit and the firewall. Now, however, the nose of the aircraft was torn because of the crash, so we could reach the bolts and unscrew the nuts.

Photo: Ari Aho

Photo: Antti Hietala

At the same time all the wires and cables, connecting the engine through the firewall, were detached. Part of them could be easily detached, but others fought us all the way. When the engine oil had been drained, we were ready to detach the engine.

Photos: Antti Hietala

Photo: Ari Aho

The engine was tied with cargo straps to an engine hoist, and the engine was pulled gingerly out of the nose of the Super Chug, hanging from the straps with the engine mounting. The detached engine was lowered on straps to a solid worktop to wait for further action.

The fuselage without the engine was still resting attached to a support frame made of pieces of four by two. Now the fuselage could be detached from the frame. The straps and other devices were opened, and the fuselage was carefully lifted from the supporting frame on to the table. We were a little apprehensive to lift the fuselage, nearly broken in half, but it held on well.

Because the fuselage of the OH-XTM has been damaged in the lower part between the cockpit and the firewall, it would be the most convenient, if the fuselage were to be on its back. So it was decided to place the fuselage on its back on two trestles, to facilitate the restoration work. One trestle would be by the cockpit opening and the other would support the rear fuselage at the stem of the vertical stabilizer.

We pondered what the suitable working height would be to restore the fuselage. It was decided to be 120 cm from the floor level. We adjusted the legs of the trestle by the cockpit so that the Super Chug’s fuselage top line, or in this case the damaged bottom line, would be at the height of 120 cm. The rear fuselage trestle had to be built.

It was built from the dismantled four by two pieces of wood of the Super Chug’s supporting frame. It resembled a normal wing trestle, only it was narrower. The level of the trestle was adjusted with a piece of fire hose used as strap, so that the whole of the fuselage was level and 120 cm from the floor.

After finishing the rear fuselage support trestle, the fuselage of the Super Chug was lifted upside down on the trestles. Thus the fuselage of the OH-XTM is ready for the restoration work.

Photos: Lassi Karivalo, unless otherwise mentioned

Translation to English: Matti Liuskallio

Super Sytky OH-XTM to be restored at Tuesday Club

Maanantai 14.4.2025 - Tuesday Club member

Suomeksi

Aviation Museum Society has received PIK-21 OH-XTM Super Sytky (in English unofficially “Super Chug”), a damaged experimental aircraft, as a donation. The OH-XTM was designed, built and owned by M.Sc.Eng. Kai Mellén. The aircraft was completed in 1982 and is a single seat Formula-V-racer of wooden construction, with a VW-1600 powerplant.

Last summer the aircraft was involved in an air accident, serious enough to damage the fuselage beyond repairing to airworthy condition. In consequence the owner of the Super Chug decided - as an alternative to wrecking it - to donate the entire aeroplane to Aviation Museum Society to be restored at the Tuesday Club. The wings of the Super Chug remained relatively undamaged.

The aircraft will not be restored to airworthy status at the Tuesday Club. It will be restored to be a whole, operable display artefact. It’s important that the prototype of the PIK-21 OH-XTM Super Chug, designed and built by Kai Mellén, will remain a display artefact and at the same time an example of the magnificent series of PIK-designed aeroplanes.

On Saturday, 12 April 2025 the delivery of OH-XTM arrived at the yard of the Finnish Aviation Museum. The Super Chug, which had been carefully tied on a trailer, was unloaded. After that the fuselage, supported by a wooden framework, was carried into a sea container for shelter. The wings and other components of the aircraft were also stored in the container.

At the Tuesday Club the restoration of the OH-XTM Super Chug won’t start immediately. We are still in the middle of restoring the OH-XEA Snoopy experimental aircraft at the Puusepäntie workshop. The restoration of OH-XTM Super Chug will commence at some point during this year.

Photos by Lassi Karivalo.

Translation to English by Matti Liuskallio.