Cleaning Bristol Blenheim BL-106 rudder pedals for painting

Keskiviikko 10.12.2025 - Tuesday Club member

Suomeksi

https://www.ilmailumuseoyhdistys.fi/blogi/2025/12/10/49878Once the pilot's seat of the Bristol Blenheim BL-106 had been restored, we continued our work on the rudder pedals. The pedals themselves are not broken; but they are heavily soiled and the aluminium parts already display corrosion-induced pitting. The steel parts of the controls are covered in rust.

This time, we began the restoration by investigating how the rudder pedals had originally been surface-treated. It seemed that the aluminium parts of the pedals were simply bare aluminium. Their surface was distinctly greenish yellow. There were also traces of grey paint found on the surface of some parts.

We consulted the Finnish Air Force Museum about the colour of this aluminium. It turned out that the aluminium parts of the rudder pedals were zinc chromated. At the same time, we asked if it was possible to determine from the serial number (50966/1), stamped on the surface, whether the pedals were manufactured in England or Finland. The serial number revealed that these pedals were made by the Finnish State Aircraft Factory (Valtion lentokonetehdas). After the serial number, there was also a small VL logo.

The interior surfaces, seats, and controls of the cockpits of Blenheim bombers, manufactured or overhauled in Finland, were painted with VL’s standard grey paint in the RAL 7005 shade. Thus, the remnants of grey paint found on the rudder pedals of the BL-106 confirmed that the same practice had been applied to this particular aircraft. However, most of the original surface paint had already worn away.

We will paint the rudder pedals with Isoguard Pansar paint for metal surfaces, in the RAL 7005 grey shade. This paint is alkyd and linseed oil based. Before applying the grey topcoat, the steel parts of the rudder pedals will be treated with clear Isotrol lacquer. The aluminium parts will be painted directly with Isoguard Pansar paint. This was also the method we used when restoring the pilot’s seat.

We began cleaning the rudder pedals of dirt, rust, and grease. The rusted steel components were mainly cleaned by mechanically grinding their corroded surfaces until they were clean. When cleaning the dirty surfaces of the aluminium parts, we first tried both Sinol and white spirit, but these were ineffective. We had to find a more suitable solvent.

We proceeded to use both Solmaster Painter's Solvent and CRC Brakleen Pro brake part cleaner. We applied these products to the various components, spreading the solvent onto the surface and into crevices with a brush. The solution was left to work for a while. After that, the surfaces were scrubbed using both soft brass and plastic brushes, and for tight gaps, even toothbrushes. A steel brush was not used, as it would have damaged the zinc chromated surface of the rudder pedals. After scrubbing, we wiped the surfaces with a cloth. The solvents proved effective at removing the sticky grease and dirt, although the treatment had to be repeated several times.

A small steam cleaner was also put into use. The surfaces were treated again with the solvents mentioned earlier and then "blasted" with the steam cleaner. The steam cleaner was very effective at removing grease and dirt, but it was not sufficiently effective against oxidised areas. After each steam cleaning, the part was wiped clean with a cloth. By repeating this method, the surfaces gradually became cleaner, as each time more dirt and remnants of old paint were removed.

After using the solvents and the steam cleaner, patches of wear caused by corrosion remained on the surface of the rudder pedals. The corrosion had already broken through the zinc chromated surface of the aluminium components, leaving them mottled. These worn areas were rough to the touch. We considered whether to leave them as they were or to sand them smoother.

Photo: Jouni Ripatti

We decided to sand them so that the corroded spots would be as inconspicuous as possible beneath the new painted surface. The corrosion patches were sanded with a scouring pad, which worked well. The more severely corroded spots had become so rough that they were carefully “carved” smooth with a thin-bladed utility knife. In this way, the corroded areas were made sufficiently smooth for painting. The rudder pedals of BL-106, mottled by corrosion, were now ready for painting.

Photos: Lassi Karivalo, unless otherwise mentioned

Translation to English: Erja Reinikainen

Painting of the Bristol Blenheim bomber pilot's seat

Keskiviikko 26.11.2025 - Tuesday Club member

Suomeksi

The pilot’s seat of the Bristol Blenheim bomber, which was assembled for the Finnish Air Force after the war and designated BL-106, has been under restoration at the Tuesday Club. This aircraft, which received the BL-106 designation, was assembled in the early 1950s from stored parts of various Blenheim individuals as a V-series aircraft. There is scarcely a single part in this aircraft from the original British-manufactured BL-106, which was flown to Finland in December 1937. The original BL-106 overturned in a forced landing on 8 June 1944 and was damaged beyond repair.

Photo: SA-kuva

The restoration of the seat from BL-106, which was assembled after the war, reached the painting phase in early autumn. In preparation for painting, we examined what kind of paint residues could be found on the seat as we cleaned the rusted or otherwise oxidised surfaces of both the seat pan and the seat frame.

After examining the surfaces, we concluded at first that the seat frame’s steel parts had been painted black. However, upon closer inspection, it became apparent that on top of the black paint there had been a layer of grey paint. This was confirmed when brackets, or clamps, were removed from the steel tubes of the seat frame, revealing grey paint underneath. Scraping the grey paint with a fingernail exposed black paint beneath the grey layer. Based on these findings, the decision was made to paint the seat grey.

The same paint was more clearly visible on the surface of the aluminium seat pan, although several different shades of grey and greenish-grey paint could be seen there. It was established that the topmost layer had been grey paint. In addition, a speck of red paint was found at the end of the handle that adjusts the tilt angle of the seat pan.

Bright green paint was also found on the aluminium parts of the control column which is attached to the seat frame. This green paint is a primer, which was used by the State Aircraft Factory. During overhauls at the State Aircraft Factory also the cockpits of Blenheims built in Britain were painted with grey paint in accordance with the VL’s standard, using shade RAL 7005. In the same way, we will paint the pilot’s seat of BL-106.

It should be noted that the cockpits of the British-manufactured Blenheim aircraft purchased by Finland were painted with the aircraft grey green shade used by the Royal Air Force (RAF Aircraft Grey Green BS381c-283).

Before painting the seat with grey paint, the steel tube frame, which had been cleaned of rust, as well as the steel parts of the aluminium seat pan, were treated with Isotrol lacquer, which is a primer that offers excellent protection against rust. In contrast, the aluminium parts do not require protective lacquer but are painted directly with Isoguard Pansar topcoat paint, which is specifically designed for metal surfaces, using shade grey (RAL 7005).

The seat frame was first treated with Isotrol lacquer. After that, the topcoat painting with Isoguard Pansar paint began with the seat pan. The inside surface of the seat pan was painted first, using brushes. Isoguard Pansar paint has the advantageous property of levelling out very well even when applied with a brush. Once the inside surface of the seat pan had dried, the outer surface was painted. After this, the seat frame was painted.

Once both the seat frame and the seat pan had been painted, the seat frame and the pan were joined together. The pan and the frame are connected to each other by a horizontal connecting tube, resembling a large cotter pin. It consists of two tubes that are pushed against each other and a locking bushing which is slid over their butt joint.

On both sides of the seat frame and of the the seat pan, there is an opening aligned for this steel tube. The ends of the connecting tube are pushed through these openings from both sides of the seat, towards each other. Once the ends of the tubes meet, the locking bushing, which is fitted onto one of the tubes, is slid over the butt joint to secure the connection and make it rigid. In this way, the seat frame and the seat pan were joined together. The connecting tube also serves as the axis that enables the adjustment of the seat pan’s tilt angle. The seat itself has its own separate mechanism for adjusting the angle.

Getting the connecting tube with its three parts into place proved to be a challenge. It took some time before the locking bushing, which secures the ends of the tubes, could be locked in place with the bolts running through the connecting tube. We had to enlarge the holes for the connecting bolts using a thin round file before we could push the bolts through the connecting tube. It was also tricky to get the bolts that prevent the connecting tube from moving sideways into place and to tighten the nuts onto their ends.

The restoration of the pilot’s seat for the Blenheim BL-106 has now been completed. Or, in fact, there is still one more task to be done. The leather surface of the grip padding on the right side of the seat is badly worn and partially torn. We are considering whether to restore or conserve this worn seat padding. We are leaning towards conservation, and for this we need an expert, since there is not enough expertise for this in the Tuesday Club.

Photos: Lassi Karivalo, unless otherwise mentioned

Translation to English: Erja Reinikainen

Restoration of the Bristol Blenheim pilot's seat under way

Maanantai 8.9.2025 - Tuesday Club member

Suomeksi

Last year we finished the restoration of the co-pilot’s stool from a V-series (BL-106) Bristol Blenheim bomber. Our object was a short-nosed Blenheim, assembled after the war from surplus parts in the 1950’s, having dual controls for training purposes. Beside the pilot’s seat there was a stool-like seat for the copilot. The controls in front of the seat were connected with rods to the captain’s controls. Mind you, that this series V-Blenheim aircraft (BL-106), assembled after the war, has in fact nothing in common with the UK-built war horse (BL-106), which was destroyed in a crash landing on 8.6.1944.

After restoring the copilot’s stool we moved our sights on the pilot’s seat. Restoring is all about cleaning the seat frame, basically a steel tube construction, from dirt, grease and rust. For the part of the seat pan, it meant cleaning the surfaces and sanding before painting. Note that the seat had no back armour.

As the first task we detached the leather-covered padding of the seat armrest to be conserved. After that we started the cleaning of the pilot’s seat. Soon we realized that cleaning would be more efficient and easier, if we could separate the aluminium seat pan and the seat frame.

Separating the seat pan and the seat frame necessitated the removing of the steel cross tube, rather like a big split pin, joining them. The cross tube consists of two tubes, joined by a butt joint, and a sleeve around the seam. We finally managed to slide the rusted sleeve from the seam and thus separate the tubes. We stripped the seat frame of all the parts that we could and detached the numerous rusty clips and other fasteners from the frame to be cleaned.

Some of the parts of the pilot’s seat were merely dirty and grimy, so to clean them for instance Fairy Power Spray was used. It removed the grease and dirt reasonably well from the surface of the parts.

The badly rusted tubes of the seat frame were cleaned by using abrasive pads, sanding papers and a steel wire brush attached to a cordless drill. For small parts, like nuts, a steel wire brush attached to a Dremel was used. The small items we detached from the frame were cleaned with an ultrasonic cleaner, which we had obtained.

When rust from the surface of the rusty tubes was removed, in places black paint was revealed. Based on that we concluded that the seat frame of steel tube structure had last been painted black. The cleaning of the tub-like aluminium part of the seat pan, made it apparent that the aluminium surface had been primed with grey primer and finished with greyish green surface coat of paint. The surface paint responds in shade to the greyish green Temalac ML 90 BS 283-shade we had already used in restoring the co-pilot’s seat. As primer we’re going to use Isotrol-lacquer and as surface paint Isoquard Panzer paint. The black paint will be the semigloss Isoquard Panzer paint.

We’ve more or less completed the cleaning the pilot’s seat from rust and grime, so the next phase will be the painting of the seat.

Photos: Lassi Karivalo

Translation to English: Matti Liuskallio

Restoration of the Blenheim navigator?s seat

Keskiviikko 18.6.2025 - Tuesday Club member

Suomeksi

We received the Blenheim V-series or “short-nosed” Blenheim’s navigator and pilot seats for restoration at the Tuesday Club.

Both the seat’s steel tubes were badly rusted, but neither seat had suffered significant damages. The navigator’s seat, or rather stool, was significantly more straightforward to restore because of its simple structure and smaller size. It would greatly help restoring the pilot’s seat, if the seat pan could be separated from the seat frame. The aim of the seat restoration is to clean the rust from the surfaces of the supportive tubes and smaller parts, grinding the aluminium surfaces and finally painting them.

We began the restoration with the navigator’s stool. The padding was detached first and the seatbelt as well. The seatbelt was partly torn and needed to see a cobbler.  The seat cover of leather has worn out and lost its colour. It needs to be conserved. We will not do it.

We examined the round shaped seat plate, bent at the edges, for shades of paint found on the surface. Light green colour was visible, under which darker green could be seen. Thus the surface of the seat plate had lastly been painted with light greenish grey paint and under it there was an older darker green paint.

Paint residue could also be found from the surface of the steel tube stem of the seat. This process was helped when the rusty stems of the seat were treated with Industrial ECO Complex Blue-solution. The solution revealed a green shade of paint on the surfaces of the tubes. In addition, some old pigment or paint chaff was scraped from the surfaces of the rusted tubes of the stem. Some of it was placed under a 600 times magnifying microscope. It turned out that there were three different layers of paint on the tubes of the stem. The lowest was brown, then grey and greenish grey on the surface, in other words the same shade that was found on the surface of the seat plate. In consequence we decided to paint the seat with the similar shade of light greenish grey paint.

To start the restoration proper, we detached the aluminium seat plate from the stem. It was fastened to the stem both with bolts and rivets. The bolts were loosened first. After that the rivets attaching a bracket to the edge of the seat in the upper part of the stem were drilled out, after which the seat plate came off the stem.

Then we started to remove the rust from the stem steel tubes. The rust was removed from the tube surfaces, so that a layer of surface paint became visible. The tubes need not be ground to gleaming metal, because we use Isotrol lacquer and paint for the painting. The Isotrol will stop the rusting from spreading, even though rust would have stayed in the rust crevices of the steel tubes.

Rust was ground off first with a coarse sanding paper, wiping the dust off at times. We then moved to finer sanding papers, feeling at the same time with fingers whether the surface of the tube was clean and smooth enough. After the coarse surfaces had become smooth and the old paint became visible, the sanding of the steel tubes was complete.

We moved on to deal with the seat plate. It was an easier task. The aluminium surfaces of the seat plate were lightly sanded with fine sanding paper. We didn’t indulge in any grinding off of the old paint. The main thing was that loose paint was removed from the seat surface and the aluminium surface became smooth.

After both the steel tube stem and the aluminium seat plate had been ground, they were lacquered with clear Isotrol, which leaves a protecting film on the metal surface. For the surface paint it was necessary to define the shade of the seat colour. We ended up with the grey green Temalac ML 90 BS 283 shade for the seat. With this formula the seat’s Isotrol oil paint was shaded.

Two Comprehensive school students, doing their work experience learning period at the Finnish Aviation Museum, painted the stem and seat plate of the navigator’s seat. Well, at first the quality of the work left something to be desired. However, with careful guidance a good result was achieved. That’s just the purpose of this kind of work experience period, isn’t it?

After the painting it was time to reassemble the seat. The glass bead blasted original assembly bolts were fitted, and the seat stem was riveted to the edge of the seat plate. The rivets were finally painted grey green, to avoid eye sore. We had a cobbler repair the seat belt. The restoration of the navigator seat in the Blenheim bomber was ready.

Photos: Lassi Karivalo

Translation to English: Matti Liuskallio