Re: Trouble with RR Trent 700 on A330-300s

Date:         10 Jun 97 00:35:01 
From:         Marc Schaeffer <marcmsc@geocities.com>
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As a result of my post in this newsgroup I got the following mail from
somebody who does not want to be named. Since the information is
excellent I decided to post it.

>I would like to get comments about the following :
>
> - Does anybody out there (perhaps from RR) have more info on these
>   gearbox bearings ?

As your follow up says, the problem is inadequate lubrication of the
bearing in the "Step-Aside" gearbox, suppplied by Hispano-Suiza. The oil
jet is a couple of inches from the bearing, and with the variability in
oil jet shape, the bearing can sometimes recieve an insufficient oil
flow. The T800 has a similar system, but the oil jet is positioned
closer to the bearing, and is thus less affected by variability. The
T700 solution is to modify the shape of the end-cap with the oil-jet, so
it looks like a lighthouse, but emitting oil not light. It's been engine
tested, and rig tested at all possible service pressures and flows, and
will provide much improved lubrication.

{ There is also a possibility that oil type is a factor. Cathay and
Dragonair use one type, and see problems...Garuda use another and have
no problems.  However, the oil jet position certainly can be improved}

> - How long such a redesign will normally take ?

A redesign can take a matter of minutes (in concept) the main timescales
are manufacture andproving the solution. RR's managed all this in under
a fortnight. Pretty fast really.

> - Who will pay the grounding and other costs ?
Ask a lawyer / accountant.

> - Are other engine series not affected (as stated in the report) by
>   these problems ?

The only similar design is the T800, and that's supplied a solution. The
RB211-524 and -535 are as tough as old boots.

--
Marc Schaeffer, Luxembourg // mailto:marcmsc@hotmail.com
Check out my B767-400/A330-200 homepage :
WWW  http://www.geocities.com/CapeCanaveral/Lab/8803/main.htm