British Air Ferries/British World Viscounts

[Dev One]

If I remember correctly the Viscount & the Valiant spars were made from DTD 610, which was very prone to stress corrosion cracking. Viscount 700 spars had to be changed at about 13000 hours for those made out of L65 (I think). I saw the very first outerwings that came in for new spars that was originally made in the Hurn production line - the workmanship was horrific - double holes & rivets that were too long and just bent over like nails, no wonder they failed the fatigue test, so later production wings were probably a lot better.
I think at that time all alloy interior parts were anodised, etch primed & painted silver & assembled with a yellow zinc chromate anti fraying compound paste. The skins were 'alclad', i.e. had an outer sheath of pure aluminium, as an aid to preventing corrosion, & which also took a high polish, whereas I think the Valiants were not.
Vanguards were I think the first to have all of their parts treated with a zinc chromate dipped process that gave the metal a transparent yellow coloured skin, but it could be damaged easily (Cannot remember the process name at the mo. Something like alodine?).Exterior paint & interior where corrosion was expected (the hydraulic bay for example was painted with a acid resistant white paint - it was the first to use Skydrol as opposed to DTD 584(?)) was painted directly onto the alodine as it seemed capable of taking the paint direct, no etch primer needed. I think the VC10 went a stage further & all surfaces were painted interior & exterior, & sealant was used on the edges of stringers & ribs to stop water ingress in the joints. One gets a lot of water in the fuselage from condensation. (The Heralds suffered badly because the stringers were top hat section spot welded to the skins, making a closed section that could not be inspected, nor assembled with zinc chromate paste!).
The biggest problem was when the rivet holes were drilled when parts were assembled, if they were not disassembled & the swarf removed before using the Zinc Chromate paste, then corrosion could start very quickly.
DC4 & 6's had transport joints in the fuslage that used 'bathtub' fittings at the longeron joints - I think these were a cast mag alloy prone to corrosion.
Keith

[DaveB]

As far as I'm aware Keith, only the TCA Vanguards ever used Skydrol.. certainly not the 951/953's. I gather it caused a little consternation at the time because it required different seals.. that and the fact that no one liked working with it

ATB
DaveB

[Garry Russell]

I think the early 700 figure was 17,000 hours and the spar needed changing

They modified the wing from the TAA aircraft onwards doubling the life and the 700D were further modded

The 701 (BEA) ,707 (Aer Lingus) and 708 (Air France) were the marks with the limited wing.

[Tomliner]

Reading this thread reminded me of something I came across whilst recently reading the biography of Sir George Edwards,and that was potential customers in North America had expressed concerns that the Viscount's wing was single spar.Maybe someone here can add something to this. EricT

[Dev One]

I only worked on the prototype Vanguard in the final assy shed & I remember the hydraulic 'cabin' was painted white & was told that it used Skydrol because it was more of a health hazard than DTD 585. There were special precautions needed & as you say special seals needed. In fact all of the hydraulic pipe runs in the fuselage were enclosed in a separate outer tube that must have been at atmoshperic pressure (unpressurised) so that if any leak did occur it would not get into the cabin.
Keith

P.S. Thanks for the hours correction for the spar life.

[Garry Russell]

The 700D, developed for the US had the mount opened up to take a wider end to the spar but I don't know how far the increase went.

The earlier modification was fitting a rubber cap and cleaning up the joint to lessen the fatigue

When you see the attachment, it's not much

[DaveB]

Hello Matey

It may well have been tried on the prototype Keith and was definitely used on the 952's (TCA specified it). I can't put my hand on the Vanguard manual I want but I've dug out the Air Bridge Ops Manual (Part 5) and it specifies DTD 585. You can bet more than a pound on it that BEA/BA specified the same (I've just found the BEA/BA Ops Manual Vol1 - Flight Management and it too states DTD 585) I think Skydrol was much more commonly used on that side of the pond which is a good enough reason for TCA to ask for it

ATB
DaveB

[Garry Russell]

Attaching the wing to a Viscount

http://i32.photobucket.com/albums/d6/Ga ... ll/VC2.jpg

[hs748flyer]

Attaching the wing to a Viscount

http://i32.photobucket.com/albums/d6/Ga ... ll/VC2.jpg

Got a 404 error on the link above.

I think it's disappointing the British didn't pay more attention to the quality of their products. Using Aluminium that contains high levels of magnesium for a start indicates a lack of quality control or lab testing.
Hearing of pilots being alarmed at the rust in the rear inspection hatch also makes you wonder why the news crews and media weren't all over BW/BAF aircraft. I guess if there was a crash or accident related to the corrosion/rust, they would've been retired sooner, modified or the airline would go bust.

I guess if BAF's mentality was about trying to entertain enthusiasts with older British types, they really needed a new business plan. Airlines keeping an old plane "for old times sake" doesn't make sense economically, unless they had full loads on every flight because of it...

Michael. T

[Dev One]

Thanks for your data DaveB. Possible as you say the prototype Vanguard used it for proving. Skydrol I believe was considered to be less of a fire risk as DTD585 was inflammable if there was a leak that created a mist.
I think the Viscount spars in L65 were larger as it has less strength than DTD 610.
The Vanguard wings were bolted to the centre section with hundreds of countersunk hexagon internal head screws/bolts. It was Vickers first box section wet wing wing I believe.
Keith