Violent engine surges

[chevol]

"I recently experienced a number of violent engine surges. It seems to happen rather late in the flights, a while after I stopped using fuel heating. I read in the OM that stopping fuel heating could cause fuel control freezing. - is this the only cause of these surges ? - if it is, should I leave fuel heating on until landing as long as OAT does not reach 10c or so? - What is the 10-minute fuel heat cycle on engine 1 and 4? Thank you for your help on this "

[BarryTheAviator]

"<!--QuoteBegin-chevol+Feb 11 2005, 08:42 AM--><div class='quotetop'>QUOTE(chevol @ Feb 11 2005, 08:42 AM)</div><div class='quotemain'><!--QuoteEBegin-->I recently experienced a number of violent engine surges. It seems to happen rather late in the flights, a while after I stopped using fuel heating. I read in the OM that stopping fuel heating could cause fuel control freezing. - is this the only cause of these surges ? - if it is, should I leave fuel heating on until landing as long as OAT does not reach 10c or so? - What is the 10-minute fuel heat cycle on engine 1 and 4? Thank you for your help on this [right][snapback]2885[/snapback][/right] <!--QuoteEnd--></div><!--QuoteEEnd--> I do not know whether the fuel heating is causing these surges (seems unlikely) but the fuel heat should only be used where TAT is -37c and you are above 36,000 feet (page 116 of the Manual). You do NOT need it just because the OAT is below 10c. AVTUR soldifies at a MUCH lower temperature than water (it doesn't actually freeze - it becomes like wax)"

[chevol]

"Thank you Barry, If it is not fuell heat then I think it could come from sudden wind changes. I am using Active Sky and I just saw on their forum (AVSIM) that this was a problem until recently. I downloaded their update which now came out and wind changes should be smoother thanks to FSUIPC 3.45. I'll try. Have good flights"