Aft and forward fuel tanks

[Rabies]

On a server today, I got a little bit of damage from heavy ground fire. I noticed one of my fuel tanks was losing fuel, I can’t remember which. I flipped the cross feed switch on in the hope to keep fuel in that tank, I’ll explain why shortly. Just on touch down, the tank gauge showed empty and the No2 engine flamed out. 
 

Now, I’ve had this happen before but with the No1 engine, hence this time I switched the cross feed on, in the hope it would transfer enough fuel so my good engine would not flame out.

 

Is the KA50 fuel system really wired in such a way that each engine is fueled by its own individual fuel tank? Surely that can’t be right? 

[Rudel_chw]

1 hour ago, Rabies said:

... I switched the cross feed on, in the hope it would transfer enough fuel so my good engine would not flame out.

My understanding is that the engines draw fuel from both tanks, the cross-feed is used to keep fuel balanced among both tanks. If one tank is damaged and loses fuel, you should close the crossfeed or else you will lose fuel from both tanks, instead of losing it only on the damaged one.

Edited May 26, 2021 by Rudel_chw

[Rabies]

1 hour ago, Rudel_chw said:

My understanding is that the engines draw fuel from both tanks, the cross-feed is used to keep fuel balanced among both tanks. If one tank is damaged and loses fuel, you should close the crossfeed or else you will lose fuel from both tanks, instead of losing it only on the damaged one.

 

That was my understanding to, I had plenty of fuel to get back hence the cross feed. But twice now, I’ve had an engine flame out when a tank has become empty. Could it be a bug? I’m not at my pc to test it right now. 

[26-J39]

Ok so,  you take a hit to the one tank and its leaking fuel.    Wouldn't turning on cross feed pump more fuel to the tank that's leaking and accelerate your fuel loss?

[AlphaOneSix]

With the crossfeed valve closed:

 

The Rear tank feeds the right engine.

The Forward tank feeds the left engine.

 

Opening the crossfeed allows both tanks to feed both engines.

 

If damage occurs to one fuel tank and you suspect that one of the fuel tanks is leaking, your best course of action is to OPEN the crossfeed and turn OFF the tank pump for the GOOD tank. This will burn more fuel faster out of the bad tank, instead of just losing it overboard. Once the bad tank nears empty, simply turn ON the tank pump for the good tank.

19 minutes ago, 26-J39 said:

Wouldn't turning on cross feed pump more fuel to the tank that's leaking and accelerate your fuel loss?

 

There are check valves that prevent fuel being pumped from the forward tank into the rear tank, and vice versa.

Edited May 26, 2021 by AlphaOneSix
changed "engine" to "tank"

[26-J39]

Thanks  A16 I was just checking the manual for clarification.

"

4. "КРАН КОЛЬЦЕВ. – ЗАКРЫТО" (Cross feed – Closed) fuel tank cross feed switch [RCTRL + RSHIFT + ;] and cover. [RALT + RCTRL + RSHIFT + ;] The crossfeed valve allows fuel supply of one engine from all tanks, in case of other engine's failure or both engines/APU supply from one tank in case of loss of fuel from the other tank (rupture by enemy fire). It's normally closed and should be open in case one of the above mentioned events occurs. Also, it is recommended to open the cross feed valve upon warning for 110 kg fuel quantity remaining in any of the tanks.

"

 

 

[Rudel_chw]

28 minutes ago, AlphaOneSix said:

With the crossfeed valve closed:

 

The Rear tank feeds the right engine.

The Forward tank feeds the left engine.

 

Opening the crossfeed allows both tanks to feed both engines.

 

If damage occurs to one fuel tank and you suspect that one of the fuel tanks is leaking, your best course of action is to OPEN the crossfeed and turn OFF the tank pump for the GOOD tank. This will burn more fuel faster out of the bad tank, instead of just losing it overboard. Once the bad tank nears empty, simply turn ON the tank pump for the good tank.

 

Thanks a lot for your clarification.

 

BTW: I loved the Presentations you did on the Mi-8 systems 

[AlphaOneSix]

1 hour ago, Rudel_chw said:

BTW: I loved the Presentations you did on the Mi-8 systems 

Thanks! I'm glad some people find them helpful.

[Sh4rk]

TL;DR

On 5/26/2021 at 7:15 AM, Rabies said:

Is the KA50 fuel system really wired in such a way that each engine is fueled by its own individual fuel tank? Surely that can’t be right? 

Short answer: Yes.

Page 13-17 of the manual: 

7 and 9 are the shutoff valves, 8 is the crossfeed.