| Long time on both to x-feed.. or take off with both on x-feed is not
| recommended. A guess would be "Not able to maintain high fuel flow
rates at
| take off power across the x-feed line".

Yes, I thought to this. But then I thought also that while using the
X-feed in real situation the engine still running is used at higher
than normal cruise settings.
So.. I still don't know..


A good answer to the original quetion could be
"Since it has happened that a take off with both X-FEED on has ended
in an accident, and nobody has still identified the cause".
But this accident has to be reported prior of March, 11, 1977, the
last revision for the manual I have.

S.