TD.
As a result of the XV249 incident, when there was evidence of a small fire on the "isolated" cross-feed pipe, two UTI's were issued in order to deterime the temp of the duct during engine start. With the aid of a simple thermocouple and a meter display, the aim was to check the serviceabilty of the shut of valves and determine the residual temperture after starting the engines on the ground. One section, dealing with remedial work states:
"Where temperatures of cross feed ducting recorded during engine ground runs exceeds 200C, both port and starboard cross feed valve and actuator assemblies are to be removed and replaced"
So it has to be assumed that it is IPT's belief that with the cross-feed selected "closed", a defective valve could result in a duct temp in excess of 200C. Although the UTI was carried out some time ago, an official report has yet to be produce. QinitiQ comment on this in their report.
I do not see what all the fuss is about in fitting this monitoring device. In the XV249 report, a guard was recommended for the selector switch. This was rejected because checks are in place, and people do not make mistakes. Now QinetiQ are saying fit a sensor because the temp of the cross-feed duct is unknown for some conditions, this is rejected, because it is believed, by none specialist, that the duct temp will never get near auto-ignition.
Lets think of the plus side of this recommendation. We would take care of the possible inadvertent selection of the cross-feed switch, highlighted in the XV249 report. If the switch was left in the wrong position the Flt Eng would see the temp rise, and question it. A defective cross feed valve would be brought to the attention on the aircrew and necessary action taken. And finally, energency engine starts in air (and they do exist) could be carried out with the Eng monitoring duct temp.
I really can not understand why crews appear to be opposed to a mod which improves flight safety, significantly.
DV