lml@lancaironline.net Mailing List Archive

You're sure all vents are operating properly. With full, or nearly full tanks, blocked vents will show up a lot faster than half, or nearly empty tanks. Because each run up seem to be progressively worse, perhaps you were pulling against a vacuum in the tank(s). Then when you opened things up and checked around, things seemed good again...of course, by then the vacuum in the tanks would have been neutralized. Long shot but worth thinking about. Chuck Jensen -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of William Miller Sent: Monday, May 18, 2009 8:38 PM To: lml@lancaironline.net Subject: [LML] FL220 [and high speed taxi] fuel flow interruption Thanks for all the great response both on and off list. Well, this morning I thought it was probably vapor lock between the fuel tank and the boost pump caused by the rapid assent after heat soaking in the hot summer sun.. There were several good threads on this which I found by searching "vapor lock" on lml. This afternoon while taxiing over to do the inspections I decided to do a series of full power runups down the runway. Initially, I noticed a reduced fuel flow around 26 gph, well below the 42 I usually see on takeoff. Oddly the power response and acceleration seemed normal but the fuel flow was low. This low reading of 26 vs 42 (normal) would have caused an aborted takeoff last Friday, so its new since the event at altitude. The first three runs, my data recorder did not record, so I went back for three more. On takeoff run number 4 I noticed a little roughness and fuel flow dropping to 22. On the 5th and last run just as I reached full throttle the engine suddenly quit completely. We towed it back, did another thorough look at gascolator, screen, lines, valve, everything. No foreign material visible anywhere. Mega fuel sump drains before and after show nothing on visual inspection. Nice blue color, no water, no grit. Disconnecting the fuel line we got solid flow on high boost at 44. Recowled and tried to redo it with my mechanic in the right seat. Now of course all is perfect. Good flow at 42, good fuel pressure. I did capture the data earlier when it failed, but could not duplicate thereafter. Nothing seemed to change by switching tanks. We are consulting TCM in the morning. My mechanic is suggesting it might be fuel control related. I don't think its contaminated fuel, but this did all start about 30 min after refueling last Friday with a big load of 92 gal out of 108 capacity. I am thinking about that ferry adventure to Pango Pango and back to Hawaii. What would cause invisible contamnition? Several responders asked for an update, so I will keep you posted. You all gave us several good places to look, but I don't want to make this post too long by detailing all the things we ruled out. This is an awesome safety resource! Thanks to all for the support. It is a riddle, wrapped in a mystery, inside an enigma... Bill Miller -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html