WinOrLose Posted September 16, 2024 Posted September 16, 2024 I had a flight where the AAR door was inadvertently opened resulting in a flame out. The dash one was isn’t totally clear in which takes priority, it states that when the AAR door is open it inhibits normal internal transfer but also states that when fuel drops below 2300 (is this total or just tanks 1&2) all the pumps will kick in to scavenge all remaining fuel.
Solution Zabuzard Posted September 16, 2024 Solution Posted September 16, 2024 When the door is open, the internal wing tanks and all ext tanks are cut off and cant feed due to pressurization changes. Further, the automatic fuel system that kicks in on low fuel is inoperative while the door is open (which is also used to turn it off again in case you have refueled after the system kicked in). The pumps you are referring to are for the internal tanks (tanks 4 and 6 to 1+2), which can still feed with the door open. 1
WinOrLose Posted September 16, 2024 Author Posted September 16, 2024 Thanks so to clarify with the door open and approx 4500lbs of internal fuel would you expect a flame out?
Zabuzard Posted September 16, 2024 Posted September 16, 2024 (edited) Depends where those 4500 lbs are located at. And how you are flying. Remember that the totalizer includes the internal wing tanks, which do not feed with the door open. So if the totalizer shows 4500 and you had the door open, it is totally possible that those 4500 lbs were in the wing tanks, not in the fuselage cells. The moment cell 1 goes dry, your engines will flame out. You can check Cell 1 fuel by holding the "Feed Tank Check" switch behind the tailhook lever. If you are flying afterburner and perhaps some negative Gs for a bit longer you can flame out easily even with all other internal tanks still full, as the pumps alone wont be able to keep up with afterburner consumption. You need a positive gravity feed to hold the engine alive during longer AB use. There is of course also the possibility that you damaged some valves or the fuselage pumps, blocking transfer between some cells. It is really hard to go in blind here. A track would be great. Edited September 16, 2024 by Zabuzard 2 1
WinOrLose Posted September 16, 2024 Author Posted September 16, 2024 11 hours ago, Zabuzard said: Depends where those 4500 lbs are located at. And how you are flying. Remember that the totalizer includes the internal wing tanks, which do not feed with the door open. So if the totalizer shows 4500 and you had the door open, it is totally possible that those 4500 lbs were in the wing tanks, not in the fuselage cells. The moment cell 1 goes dry, your engines will flame out. You can check Cell 1 fuel by holding the "Feed Tank Check" switch behind the tailhook lever. If you are flying afterburner and perhaps some negative Gs for a bit longer you can flame out easily even with all other internal tanks still full, as the pumps alone wont be able to keep up with afterburner consumption. You need a positive gravity feed to hold the engine alive during longer AB use. There is of course also the possibility that you damaged some valves or the fuselage pumps, blocking transfer between some cells. It is really hard to go in blind here. A track would be great. Thanks for the reply - it wont allow me to upload the track as its 153mb. It was a leisurely Sunday flight, AB only on take off and no violent manoeuvres. Totally accept that this was a result of inadvertently opening the AAR door.
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