Cockpit re-paint

[AJW]

I have just been browsing through some snaps of the VC10 and I have noticed that almost all of them appear to have had a section around the cockpit re-painted (the same section on each a/c)

What was the significance of this? Some fault found on a few and the fleet had to have it rectified??

Here is a photo showing the patch in question:

http://www.airliners.net/photo/UK---Air ... 1a180c967f

[Tonkenna]

It isn't anything like that... when they are first painted they don't look like that, but after a while different ares do look like different shades of grey. No idea why, but they are not painted like that on purpose...

Tonks

[AJW]

Sorry, I obviously didnt make myself clear!

I don't mean it was deliberately painted that colour, I am well aware that it won't be an exact match to older paint due to fading etc.........It was more why has every aircraft had that specific area re-painted? :/

[Tonkenna]

I did understand what you meant, sorry, perhaps my explanation was not clear.

That area has not been specifically painted, it is the way the paint reacts to various panels etc. The jets are painted overall and that effect happens over time...

Tonks

[Laurieg]

Just had a chat with one of our design experts, (painters to you and me), and he said that the area around and above the flight deck is a different paint, to that of the rest of the aircraft, (he said it is coded FLS instead of FLH). It also runs along the spine of the aircraft, although you cannot see it from the ground. I had a look at the two frames we have here from the mezanine and he was right! He believes that it has better reflective qualities for those areas. Got to look after you crew's sensitive skins

[AJW]

Thanks for the info guys

I though some of the pics showed it down the spine too!

[Tonkenna]

Well there ya go, never knew that... I have watched a VC10 being painted in the past and didn't see them do the area separately, but that was a few years ago in France.

We are well worth looking after Laurie

[Jelle Hieminga]

And so you learn something new. I was thinking it might be something to do with different base metal in that area, never would've guessed different paint!

[Tonkenna]

That is exactly what I had always been led to believe... but then again I never asked a painter

Tonks

[Laurieg]

I will get the technical specs tomorrow. I think I may have got the coding wrong, the guy seemed overjoyed that I had asked!

[Tonkenna]

He is probably amazed that anyone should ask him... I think they are used to living in a world of paint haze were no one can talk to them!

Tonks

[DangerMouse]

It is different paint but there is a reason... It's not just for its reflective properties but mainly for NDT purposes around the cockpit.

[AJW]

Ah......I guess the cockpit is prone to extra damage eg wind buffeting or cracking then? I know the 747's have problems with damage to the upper cockpit area from wind buffeting especially.

[karenspalding]

The sole reason for the whole operation is to reduce the temperature of the cabin whilst it's sat on the ground. During tests it was proven to reduce the temperature by around 5 celsius. The crews were desperate for help in this area so the decision was taken to carry it out on every repaint even though it extended the servicing by one full day.

To offer a technical overview; the entire airframe excluding the cockpit and spine have a black primer applied underneath the topcoat. The topcoat on these black primed areas is called LIR (which stands for Low Infra Red). The topcoat is applied to a very strict tolerance to provide the aircraft with a low infra red signature. The opaque shade of grey you can see is actually the effect of the black primer showing through as the topcoat is applied very thinly (it is the the black primer that provides the LIR properties, not the topcoat, although the two obviously work in conjunction with one another).
The cockpit and spine areas have a yellow primer applied, also followed by a white epoxy intermediate coat. The topcoat in these areas is called SHR (which stands for Solar Heat Reflective). The SHR property of this finish only works with the white intermediate coat applied underneath it. Again the tolerances are very strict and what the naked eye sees is the effect of the white intermediate coat showing through.

The NDT comment is incorrect. It is completely possible to measure through paint on any area of the aircraft as long as the paint is in sound, unbroken condition. Just ask any of the NDT team.

[Anglojet]

Noticed on 148 yesterday that the 'Royal Air Force' lettering by the front door is actually black primer that is covered when the grey top coat is applied. Clever.