Painting of the Bristol Blenheim bomber pilot's seat

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