IRU Rack Removal?

[Pengineer]

Has anyone out there ever removed or installed an ADIRU tray on an A320 or an IRU tray on a 757 or 737-4? If so whats involved in setting it up, do you need any specialist tools, knowledge or equipment.

PS Theres nothing in the book, it just says don't do it!

[oh_ring]

Seen it done on a 757 subject to the attentions of a Boeing team after a hard landing @ Funchal. Hard landing? Nose gear torque box change. Flt deck floor was level with galley 1. Anyway, they had the aircraft levelled and installed an IRU with rack on a floor beam in the centre of the cabin (floor was up). Rack was supplied with extension cable to the E/E bay. Calibrated by PFM but all worked OK. E/E rack had been pushed up to keep the torque box company.

[agazou]

Had a recent problem on an A321 Airbus Industrie reckon they are the only one's qualified to remove/refit ADIRU racks. Required laser alignment tooling, they will not accept accuracy of digital clino. As you say the book says don't do it.

[Pengineer]

Anyone else?

[Lamptramp]

If you can avoid removing the rack do so my understanding is that should it have to come out re-alignment has to be carried out by a Boeing specialised team.
It did get close on a 737-400 a few weeks ago but the rack did in fact stay put I'm glad to say!

[This message has been edited by Lamptramp (edited 12 February 2001).]

[Pengineer]

Agabou, are you sure about that bit about the lasers when you did the A321? do you have anything in writing about a clino not being accurate enough?

Anybody else ever done it or heard a scry story about doing it?

[agazou]

But of course. ze French will accept nothing less. Be it big strimmer or standard strimmer it's all the same. There's a water ingress mod that's been done some time back, look at that for the tooling, nothings mentiones cos you're not supposed to take the rack out Only the manufacturer is alleged to have to knowhow, oh and laser alignment gear to ensure the rack is straight and level when fitted.

[Blacksheep]

For what its worth we installed a Honeywell "LaserNav" system in our 737s a few years ago. The rack wasn't a big problem as long as it went in exactly as per the drawings but we had a set of complex alignment procedures to do with assistance from Honeywell engineers. Memory is a bit hazy now but as far as I remember, this involved lining up the aircraft on an accurate heading using brass studs set into the hangar floor. Surveyors (the kind with theodolites, not the CAA variety!) had first surveyed and marked an accurate line and installed the studs. We then lined the aircraft up on the studs. The checks assessed the alignment of the gyros by comparing the earth rate figures obtained from the gyros to the calculated rates based on the accurately known aircraft alignment.

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Through difficulties to the cinema