I'm trying to figure out why I keep losing power at cruise.  I have the auto throttle, and AP on in VNAV and LNAV mode.  Everything just goes completely dark.  Not like running out of fuel, no engine fire, nothing.  I know, i'm not giving much to work with here but any help would be appreciated.

Alternator?

Fuel selector?

Edited March 3, 20188 yr by fppilot

Do you have hardware levers assigned to mixture controls? (For use with piston engine sim aircraft)? 

If so, by default they will map to the engine fuel shutoff levers when the Maddog is loaded. If they get bumped, or generate a noise spike, they could cause the engines to flame out, which would quickly result in a loss of the engine generators and most of your electrical power.

I’ve read several other reports of power loss in flight , so something else may be going on in the Maddog X for some users, but hardware mixture controls can definitely cause this issue.

Very sorry to hear you're having problems.

Something else that may be causing this... something built into the Maddog software...

How are your fuel temps?  The MD-80 has a real world problem with freezing fuel (especially in and around the fuel filters) and this is modeled in the sim.  I switch the heaters on anytime the temps drop below zero (0 degrees Celcuis) but if the temps get below -6 then you're going to have issues.  Below is a good and short article about this.

"Fuel heat should be operated by momentary actuation of the left and right fuel heat switches for
one cycle (on minute duration) before takeoff if indicated fuel temperature is 0°C or below.
C/M--2 observe FUEL HEAT lights coming on followed by fuel temperature and oil temperature
increase and going off after one minute "

Best wishes!

https://www.flightglobal.com/FlightPDFArchive/1992/1992 - 0060.PDF

 

2 hours ago, eefields said:

I'm trying to figure out why I keep losing power at cruise.  I have the auto throttle, and AP on in VNAV and LNAV mode.  Everything just goes completely dark.  Not like running out of fuel, no engine fire, nothing.  I know, i'm not giving much to work with here but any help would be appreciated.

Fuel icing ?

25 minutes ago, TopGun33 said:

Fuel icing ?

Possibly! See post directly above yours my friend.

Best wishes!

 

Both Engine flame out due engine ice?

I remember when flying Spanair virtual routes (until 2012), I was coming back from EDDM to LEBL and near to LEGE the cockpit got dark and silent. Was pitch black because night and I was navigating next to thunderstorms.

Autopilot disconnected so hand flyied the descent, starting APU, and tryied to restart the engines.

Was incredible to land in LEGE with one engine as I could manage to restart it.

This aircraft is absolute marvellous!

1 hour ago, DaveCT2003 said:

Possibly! See post directly above yours my friend.

Yes saw that Dave.

Thank you.

6 hours ago, DaveCT2003 said:

Very sorry to hear you're having problems.

Something else that may be causing this... something built into the Maddog software...

How are your fuel temps?  The MD-80 has a real world problem with freezing fuel (especially in and around the fuel filters) and this is modeled in the sim.  I switch the heaters on anytime the temps drop below zero (0 degrees Celcuis) but if the temps get below -6 then you're going to have issues.  Below is a good and short article about this.

"Fuel heat should be operated by momentary actuation of the left and right fuel heat switches for
one cycle (on minute duration) before takeoff if indicated fuel temperature is 0°C or below.
C/M--2 observe FUEL HEAT lights coming on followed by fuel temperature and oil temperature
increase and going off after one minute "

Best wishes!

https://www.flightglobal.com/FlightPDFArchive/1992/1992 - 0060.PDF

 

Probably you mistake freezing "fuel" with water droplets in the fuel tanks - often released by the fuel as it cools down which tend to accumulate near the bottom of said fuel tanks and can (but may not) clog fuel pipes and fuel filters...these drops can be super cooled by nature and will freeze on any surface it touches.

Jet A fuel freezes at -40c (A1 at -47). So the actual fuel is not the issue it is water, dirt and other particles (in any shape)

The article you linked to deals with a totally different topic, ice accumulation on top of the wing surface. Aircraft which have the modification according to the article have their center pumps with AUTO OFF ON positions. The purpose of AUTO logic minimizes contact between the coldest fuel in the tanks and the upper part of the wing. Again not the same thing as flipping on FUEL HEAT. "Fuel heat is used to prevent or remove ice on the fuel filter" according to the operations manual.

See image below of the "new" design of center pumps (from hilmerby.com)

BR

Edited March 3, 20188 yr by SAS443

9 hours ago, eefields said:

I'm trying to figure out why I keep losing power at cruise.  I have the auto throttle, and AP on in VNAV and LNAV mode.  Everything just goes completely dark.  Not like running out of fuel, no engine fire, nothing.  I know, i'm not giving much to work with here but any help would be appreciated.

Did you get FUEL FILTER PRESS DROP indication at all? And even if you did, a bypass valve would allow the fuel to pass by a clogged filter regardless.

Also, Did you have the chance to check the position of the FUEL LEVERS?

7 hours ago, SAS443 said:

The article you linked to deals with a totally different topic, ice accumulation on top of the wing surface.

Yeah, darn it, wrong link.  I'll have to try and find the correct one. Thanks for pointing that out!

 

I bet it is the icing.  I was paying no attention to the fuel temp and using the fuel heaters.  That makes sense. I'm in flight now so I will watch it again and see what happens!  Thanks for the help!

@DaveCT2003 thanks for the tip regarding fuel heat. I'm having a similar issue as well, but in my scenario my fuel control valves will shut to cut off? I have FS2crew - not sure if that would cause anything.

@hqmurphy I'm also using FS2Crew.  I don't think that is contributing to it but I find I have to hard mute this FS2crew because it picks up sounds around me and does things when I don't want it to.  

 

So, on  the fuel heat, do you just keep flipping the Fuel Heat switches when the fuel nears 0 degrees to keep it from freezing?

23 minutes ago, hqmurphy said:

@DaveCT2003 thanks for the tip regarding fuel heat. I'm having a similar issue as well, but in my scenario my fuel control valves will shut to cut off? I have FS2crew - not sure if that would cause anything.

if Fuel switches are automaticly moved to Cutoff and you did not receive any kind of caution messages - it probably isn't related to Fuel heat.

 

11 minutes ago, eefields said:

@hqmurphy  So, on  the fuel heat, do you just keep flipping the Fuel Heat switches when the fuel nears 0 degrees to keep it from freezing?

Again, it's not the fuel that is freezing, it's formation of ice/debris on the fuel filter. And the 0 degrees Celcius is your crucial value before TO and Approach (remember you cant either Takeoff or shoot an approach with FUEL HEAT ON

Before Take off:
Use both Left/Right Fuel heat simultaneously.  These switches control a bleed air shut off valve and the valve will automatically close after 1 min (also the ON position is momentary, it will return to OFF right away)

Cruise
 If the FUEL FILTER PRES DROP light comes on during cruise use the fuel heat as required.

Descent/Approach:
Activate fuel heat, one engine at a time, for one cycle prior to final approach if fuel temperature is 0°C or below. Fuel heat operation should be completed prior to final approach.

There really isn't much more mystique about this. The engines should not just die the way you are experiencing it. at least you should get a fuel filter-warning...