Funny Flight timer/fuel computer readings

[dougnlina]

We are in the initial phases of test flying a PA-18 Replica kit. I am having strange readings on the fuel computer and timers. Specifically, the Gallons remaining is way off even though the Gallons used seems to be in the ballpark. Also the air trip is higher than it should be, although run time and air time seem correct. I assume I have some setting off kilter, maybe someone can clue me in.

And yes, we are fighting high #4 Cylinder temps

 

[dynonsupport]

It's not unusual to have to calibrate (tweak) the fuel flow sensor's parameters for a particular aircraft's fuel system to optimize the accuracy of the SkyView Fuel Computer. See Fuel Computer Configuration, Page 7-67, Revision V, of the SkyView System Installation Guide.

We are in the initial phases of test flying a PA-18 Replica kit.  I am having strange readings on the fuel computer and timers.  Specifically, the Gallons remaining is way off even though the Gallons used seems to be in the ballpark.  Also the air trip is higher than it should be, although run time and air time seem correct.  I assume I have some setting off kilter, maybe someone can clue me in.

And yes, we are fighting high #4 Cylinder temps

 

[Dynon]

So the gallons remaining doesn't know what's in the tanks. You need to tell it when you fill up. You can set it by going to EMS > FUEL. Now, if you also have in-tank sensors, SkyView will pipe up with an alert when you turn it on after a fill-up and it will automatically prompt you to adjust the fuel computer.

The AIR TRIP timer is like the trip timer on your car's odometer: it only resets when you reset it. In contrast, the AIR TIME resets every time you take off. Here's the full explanation of all of the timers, which you can find in the SkyView Pilots User Guide on our website:

The Engine Run Timer - labeled RUN TIME when displayed on an Engine Page - is a Hobbs style
timer that records the time your engine has been running during your current flight. It resets
the first time the engine is started after SkyView is powered on. This allows you to view your
previous flight’s Engine Run Time any time before you start your engine before a flight.

The Engine Trip Timer - labeled TRIP RUN when displayed on an Engine Page - is a Hobbs style
timer that records the time your engine has been running. Unlike the Hobbs time, it can be
reset by pressing ENGINE > CLR TMR.

The Total Air Timer - labeled AIR TOTAL when displayed on an Engine Page - runs any time that
SkyView determines that the aircraft is in flight. SkyView uses the presence of significant
airspeed or GPS speed to decide whether the aircraft is flying. This timer can only be reset or
adjusted in the Aircraft Information menu within SkyView Setup. See the SkyView System
Installation Guide for information about using SkyView’s Setup Menu.

The Air Timer - labeled AIR TIME when displayed on an Engine Page - runs any time SkyView
determines the aircraft is in flight. SkyView uses the presence of significant airspeed or GPS
speed to decide whether the aircraft is flying. Resets as SkyView detects that the aircraft has
transition to “in the air” This time is also optionally used to calculate the Switch Fuel Tank
Reminder.

The Air Trip Timer - labeled AIR TRIP when displayed on an Engine Page -runs any time that
SkyView determines that the aircraft is in flight, just like the Total Flight Timer. Unlike the Total
Air Timer, it can be reset by pressing ENGINE > CLR TMR.

 

[dougnlina]

I think I may have found a bug in at least our system. If I fuel up, and update the computer to show full tanks, it accepts the amount and shows the proper fuel remaining. However I have been shutting down the system after this updating of the quantity. When I boot it back up, the fuel remaining is different, usually less, and occasionally negative. Then if I update the quantity again, and do not shut down the master but start the engine and fly, the fuel computer acts correctly and is quite accurate. So it is only goofy when I shut it down immediately after updating the quantity ( incidentally always to full tanks so far) BTW this display has had a system 5 and is due to get shipped in, I just have not pulled it from the panel yet

 

[dynonsupport]

First, the System Event 5 warning is describing that there ARE read/write errors occurring in the SkyView display's Solid State Disk (SSD), aka flash memory, so it's possible that the problems in the SSD are occurring where the fuel level data is stored. Thus, it's quite possible that after you have your SkyView display repaired for the System Event 5 issue, this issue will no longer occur.

System Event 5 aside, we've seen similar issues with other customers. Because flash memory doesn't have an infinite number of read/write cycles, we're a bit conservative about writing updates to it - SkyView does so only periodically. You don't notice because SkyView is powered up and mostly operating from its volatile memory (RAM). Thus, in some limited circumstances, the system doesn't get a chance to write a changed value from RAM to the flash memory and, if another display is installed, doesn't get a chance to synchronize the changed information in the flash memory in both displays.

Do you have a backup battery on your display(s)? If not, changing the value then shutting off the SkyView display doesn't give the SkyView display a chance to update the non-volatile memory. Having a backup battery gives the SkyView time to recognize that system that power is removed and the system is shutting down, update the non-volatile NOW.

We have improved this issue with recent versions of SkyView firmware, so if your system doesn't have the latest firmware, I suggest updating to the latest (v13.0.3).

I think I may have found a bug in at least our system.  If I fuel up, and update the computer to show full tanks, it accepts the amount and shows the proper fuel remaining.  However I have been shutting down the system after this updating of the quantity. When I boot it back up, the fuel remaining is different, usually less, and occasionally negative.  Then if I update the quantity again, and do not shut down the master but start the engine and fly, the fuel computer acts correctly and is quite accurate.  So it is only goofy when I shut it down immediately after updating the quantity ( incidentally always to full tanks so far) BTW this display has had a system 5 and is due to get shipped in, I just have not pulled it from the panel yet

 

[dougnlina]

Software us up to date. It is a dual 7" system and only the LS display has the backup battery, and I had been doing the updates on the RS screen, and shutting it down pretty quickly. If the engine runs at all all the timers/fuel totalizers work perfectly, so sounds as you describe, I was essentially not giving it enough time to write the new value.
Thank You
DP