MU3001A
Thanks for the info. See above, and below.
grebllaw123d
If the SOP was followed, and I have no reason to believe otherwise, the CTR tank became empty LONG before arriving LHR (as already mentioned in many posts).
Forgive me, but I would re-write this as “If the system functioned as per design intent the CTR tank became empty of fuel…”.
BTW, anyone who has worked in tanks will be aware that there is no such thing as an empty tank in operational aircraft. Those who have been involved in fuel systems design or support will be aware that there is always an unpumpable volume and there is always an undrainable volume.
Any fuel left would imply double scavenge pump failure - very unlikely!
The causes of this accident were very unlikely. The water scavenge systems and the fuel scavenge systems may have been compromised by FOD or ice. Failure of unsignalled systems is dormant i.e. they may have been failed for years with no indication, unless there is a secondary effect e.g. uncommanded tank transfers. Ice in the CT would have thawed only during the later part of descent, starting with that in the sections of the CT exposed to external temperatures.
In any case the AAIB report states that there was an indicated fuel load of 10500 kg upon arrival - distributed between the 2 wing tanks (5100 kg and 5400 kg). Nothing is mentioned about fuel in the CTR tank.
Correct.
Also "the flight was uneventful until the later stages of the approach"
Agreed. So it’s a reasonable assumption that there were no failure warnings.
With the information we have received (so far), I cannot see that the CTR tank played any part in the accident.
Agreed. Also, with the information we have received (so far), I cannot see that the CTR tank did not play any part in the accident.
Here’s a process.
1) Understand the system
2) Find all possible ways in which combinations of failures could have the potential to cause the observed failure effect (regardless of your opinion as to their probability).
3) For each postulated failure mode, work out what evidence it would leave behind.
4) Look for evidence.
5) Rule out (and if you’re lucky, rule in) failure modes based on evidence.
It looks like my centre tank feed theory can probably be ruled out (as posted above) as the AAIB would have almost certainly seen indication of CT pumps running from the FDR.
So, my analysis is running on fumes and unless someone gets me a system schematic, FDR parameter list, system description or training notes soon, I’m off to bed.