july865 Posted June 26, 2018 Posted June 26, 2018 (edited) I created a simple "Air Start" mission with 4 F18's. all of the F18's have an "APU ACCUM" advisory. . . the manual states "APU ACC. Indicates that the APU accumulator pressure necessary for the starting the engine is inadequate." 2 question. what did i do during the mission creation cause this warning, and how do i get rid of it in flight (makes good practice)?? and can someone explain the warning in a bit more detail so i can understand the advisory better? Edited June 26, 2018 by july865 added pics Asus x99, i7 5930k, 32g mem, MSI 1070GTX, 970 Samsung M.2, LG 35in Ultra-Wide, TrackIR 4 Thrustmaster Warthog HOTAS [sIGPIC][/sIGPIC]
luft Posted June 26, 2018 Posted June 26, 2018 The accumulator physically is a cylinder loaded with nitrogen and hydraulic fluid from the hydraulic system 2B. In the preparation of the plane for the flight, by ground staff, and thanks to a hand pump the system is charged. When you connect the APU and thanks to the nitrogen pressure, the hydraulic fluid moves the starter motor of the APU, it starts to turn and ignites with the combustion of the fuel. When we see the caution APU ACCUM, it warns us that the accumulator of the APU does not have enough charge to carry out this start-up or other of the functions assigned to it, such as extraction of the landing gear in emergency, emergency brakes, and others. Sorry my english I hope it is understood [sIGPIC][/sIGPIC]
HawkDCS Posted June 26, 2018 Posted June 26, 2018 Does it have to be recharged by ground crew? Or can it be recharged with bleed air or something on the plane? Rig: 5960X @ 4.5GHZ 32GB 3000Mhz DDR4 Titan XP Dell 3415W 21:9 Thrustmaster Warthog
Rudel_chw Posted June 26, 2018 Posted June 26, 2018 Does it have to be recharged by ground crew? Or can it be recharged with bleed air or something on the plane? I havent actually tried it, but the manual says that the Hydraulic Isolate Switch (rear of left console) when set to ORIDE allows in-flight recharging of APU accumulator. For work: iMac mid-2010 of 27" - Core i7 870 - 6 GB DDR3 1333 MHz - ATI HD5670 - SSD 256 GB - HDD 2 TB - macOS High Sierra For Gaming: 34" Monitor - Ryzen 3600 - 32 GB DDR4 2400 - nVidia RTX2080 - SSD 1.25 TB - HDD 10 TB - Win10 Pro - TM HOTAS Cougar Mobile: iPad Pro 12.9" of 256 GB
GPVM Posted June 26, 2018 Posted June 26, 2018 Does it have to be recharged by ground crew? Or can it be recharged with bleed air or something on the plane?If the pilot starts the APU during ground start-up and shuts it down without starting the right engine, then the ground crew must recharge it manually. Otherwise normally the APU should recharge itself once the right engine is up and running. Starting the left first won't recharge it as it is not connected. Not sure why the warning is on in flight though. Lähetetty minun ONEPLUS A6003 laitteesta Tapatalkilla
Flamin_Squirrel Posted June 26, 2018 Posted June 26, 2018 The accumulator physically is a cylinder loaded with nitrogen and hydraulic fluid from the hydraulic system 2B. In the preparation of the plane for the flight, by ground staff, and thanks to a hand pump the system is charged. When you connect the APU and thanks to the nitrogen pressure, the hydraulic fluid moves the starter motor of the APU, it starts to turn and ignites with the combustion of the fuel. When we see the caution APU ACCUM, it warns us that the accumulator of the APU does not have enough charge to carry out this start-up or other of the functions assigned to it, such as extraction of the landing gear in emergency, emergency brakes, and others. Sorry my english I hope it is understood Some good info, but not quite right. There are two accumulators. Here's the info from NATOPS 2.7.4 Accumulators. Two accumulators are provided in the system 2 circuitry, an auxiliary power unit (APU) accumulator and a brake accumulator. Both accumulators can be charged with a hand pump on the ground. In flight the APU accumulator can be charged from circuit 2B by positioning the Hydraulic Isolation Override switch (HYD ISO) to ORIDE. It is recommended that the switch be held in ORIDE for at least 10 seconds to get a full charge. The brake accumulator is continuously charged in flight by a trickle charge restrictor in circuit 2A. The brake accumulator can also be charged in flight by circuit 2B if the HYD ISO switch is positioned to ORIDE and either: (a) Emergency landing gear extension is selected or, (b) Emergency IFR probe extension is selected. The APU accumulator serves to start the APU and to provide emergency back-up hydraulic power to refuel probe extension and nosewheel steering. The brake accumulator, in conjunction with the APU accumulator, provides emergency pressure to unlock/lock the landing gear and operate the brakes. A brake accumulator pressure gage is provided on the lower left instrument panel. Another brake accumulator pressure gage is provided in the nose wheelwell. Both gages receive the same signal from a common sensor on the brake accumulator manifold. HYD 2A pressure, through a trickle charge restrictor, compensates the brake accumulator for temperature changes and normal internal leakage when the hydraulic isolate valve is closed.
july865 Posted June 26, 2018 Author Posted June 26, 2018 I havent actually tried it, but the manual says that the Hydraulic Isolate Switch (rear of left console) when set to ORIDE allows in-flight recharging of APU accumulator. with these instructions and the NATOPS instruction, hold the switch for 10sec. does that sound correct?? (not able to test for several hours) Asus x99, i7 5930k, 32g mem, MSI 1070GTX, 970 Samsung M.2, LG 35in Ultra-Wide, TrackIR 4 Thrustmaster Warthog HOTAS [sIGPIC][/sIGPIC]
Flamin_Squirrel Posted June 26, 2018 Posted June 26, 2018 with these instructions and the NATOPS instruction, hold the switch for 10sec. does that sound correct?? (not able to test for several hours) Yes, but the valve opened by the override is also open with weight on wheels. So unless directed by an emergency procedure, you don't need to use it.
july865 Posted June 26, 2018 Author Posted June 26, 2018 (edited) Yes, but the valve opened by the override is also open with weight on wheels. So unless directed by an emergency procedure, you don't need to use it. thank you. so, if this were to happen in flight, which the F18 is currently set to air start at 20k. then this warning would be noted and cleared, since there is no emergency? Edited June 26, 2018 by july865 spelling Asus x99, i7 5930k, 32g mem, MSI 1070GTX, 970 Samsung M.2, LG 35in Ultra-Wide, TrackIR 4 Thrustmaster Warthog HOTAS [sIGPIC][/sIGPIC]
did Posted June 26, 2018 Posted June 26, 2018 Always start the right engine first. If not, then do a crossbleed start. L eng at 80% bleed air and crank.
july865 Posted June 27, 2018 Author Posted June 27, 2018 @did the mission is an air start, when i enter the office, the APU ACCUM adv comes on Asus x99, i7 5930k, 32g mem, MSI 1070GTX, 970 Samsung M.2, LG 35in Ultra-Wide, TrackIR 4 Thrustmaster Warthog HOTAS [sIGPIC][/sIGPIC]
BigMac Posted August 21, 2018 Posted August 21, 2018 I'm getting this issue every time I start a mission in the air eg Instant Action AG Guns & Rockets mission. When I click FLY I get a Master Caution and it's the APU ACCUM warning which I can clear by changing to OVERIDE as described above, a few seconds later, I hear the APU shutdown. Have had this bug for a few months now.
RobertFriday Posted August 22, 2018 Posted August 22, 2018 If you are using a warthog throttle and have your apu switch mapped to it, make sure it’s not left on... I might know from experience
=Panther= Posted August 22, 2018 Posted August 22, 2018 I'm getting this issue every time I start a mission in the air eg Instant Action AG Guns & Rockets mission. When I click FLY I get a Master Caution and it's the APU ACCUM warning which I can clear by changing to OVERIDE as described above, a few seconds later, I hear the APU shutdown. Have had this bug for a few months now. If you're in the air, the APU shouldn't be on. If so either make sure your controls are set to off if you have APU switch mapped to controller. Or if that isn't the case, the mission needs to be updated to have the APU in the off state on loading. Twitch Channel [sIGPIC][/sIGPIC] Virtual Thunderbirds, LLC | Sponsored by Thrustmaster Z390 Aorus Xtreme, i9 9900k, G.SKILL TridentZ Series 32GB, 1080ti 11GB, Obutto R3Volution, Thrustmaster HOTAS Warthog, TPR, Cougar MFDs, FSSB R3L, JetSeat, Oculus Rift S, Buddy-Fox A-10C UFC, F/A-18C UFC, Tek Creations F-16 ICP
BigMac Posted August 22, 2018 Posted August 22, 2018 Robert, Panther - Gents I feel so dumb, that's exactly what the problem was. Never use that switch on my Warthog throttle now and must have moved it when I cleaned it LOL. Huge thanks for your wiser thoughts.
aceofspades9963 Posted August 22, 2018 Posted August 22, 2018 Yea figured that's what it was , one thing that I noticed is the APU ACC caution won't go away on the right panel until #2 is running but it should extinguish about 5-10 sec after cranking the #2 engine since the ats is turning the amad which turns the hyd pump charging the apu accumulator.
macedk Posted August 23, 2018 Posted August 23, 2018 Good old switc'a' rooo ;) OS: Win10 home 64bit*MB: Asus Strix Z270F/ CPU: Intel I7 7700k /Ram:32gb_ddr4 GFX: Nvidia Asus 1080 8Gb Mon: Asus vg2448qe 24" Disk: SSD Stick: TM Warthog #1400/Saitek pro pedals/TIR5/TM MFDs [sIGPIC][/sIGPIC]
Leostra Posted March 1, 2020 Posted March 1, 2020 THANK YOU! This worked and I can use my Autopilot again after switching to ORIDE I appreciate the effort to assist in this issue.
Banman Posted March 1, 2020 Posted March 1, 2020 I have accidentally hit the (wrong switch) APU switch to on during flight and I have got the warning message. I would turn the APU off immediately but the caution warning would not go away with obviously the right engine running. Seems like if you are in flight the right engine would automatically charge the system and the warning should self clear? Even after acknowledging the Master Caution it would not clear. Guess I will try this if / when I do it again. Thanks! i7-8700K (6 Core, 12MB Cache, 4.6GHz) 32 GB DDR4 XMP @ 2933MHz, GTX 1080Ti w/ 11GB GDDR5X, Windows 10 Pro, 256GB SSD, TM Warthog Stick & Throttle, TM TPR Pedals, TrackIR5
Robin_Hood Posted March 1, 2020 Posted March 1, 2020 On the contrary. As has been mentionned earlier (with references to the NATOPS), the valve that allow the APU accumulator to be recharged is open with weight-on-wheels (so it should charge on the ground with the right engine running), but closed in flight (so that in the event of a leak in the right hydraulic system, you can keep some pressure for essential systems). To recharge the APU accumulator in flight, you need to hold the HYD ISOL (hydraulic isolation) switch on the left console, which will open the valve temporarily and should clear the caution. 1 2nd French Fighter Squadron
Tusky Posted March 28, 2021 Posted March 28, 2021 (edited) I'll bring up this topic again since I'm running some tests on warnings and emergencies... After how many APU restarts will the APU not start when the APU ACC warning is on? On ground, I stopped at ten and it still could be started. Are APU ACC effects modelled or not?... Edited March 28, 2021 by Xamik75
Swift. Posted March 28, 2021 Posted March 28, 2021 1 hour ago, Xamik75 said: I'll bring up this topic again since I'm running some tests on warnings and emergencies... After how many APU restarts will the APU not start when the APU ACC warning is on? On ground, I stopped at ten and it still could be started. Are APU ACC effects modelled or not?... They used to be, wouldn't be the first time ED regressed in the sake of gameplay 1 476th Discord | 476th Website | Swift Youtube Ryzen 5800x, RTX 4070ti, 64GB, Quest 2
Tusky Posted March 28, 2021 Posted March 28, 2021 hace 2 horas, Swiftwin9s dijo: They used to be, wouldn't be the first time ED regressed in the sake of gameplay Of course, no engine was ON because I wanted to deplete the APU Accumulator. I'll try in flight...
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