Fuel Flow Monitoring

* This is an outgrowth of the hot starting fuel injection thread

For those of you who have JPI or EDI fuel flow monitoring:
a) how many flights did you make before it was "calibrated"?
b) how much variance do you see from flight to flight?
b1) do you fly approximately the same altitudes/power settings each
flight?


My case:
I rent a 1978 Cherokee Six with an FS-450.
I flew it to Oshkosh 2002. Keeping track of flight and leg times on
each of the four tanks, I learned that the gauge was reading 25% too
high.
As I was more interested in flying than playing with the flow gauge, it
was not until last month that I finally got around to performing the
first correction.
As I said, it was reading high, so the correction is to add the
percentage of the currently indicated K-factor to that K-factor.
That done, a second flight was flown and the times and quantities
recorded. This time, the flow was 13% low.
Subtract this percentage from the current K-factor.
Go fly again, record time and quantity. High by 13%. Add that to the
current K-factor.
The subsequent two flights were 0.4 gph over and 0.1 gph over.
Close enough!

"EDR" wrote:
For those of you who have JPI or EDI fuel flow monitoring:
a) how many flights did you make before it was "calibrated"?

Mine did not require calibration. It has been accurate since
installation.

b) how much variance do you see from flight to flight?

If the JPI says I burned 40 gallons, the pump will say 39-41. It's
usually a bit less than what the JPI said I burned.

b1) do you fly approximately the same altitudes/power settings each
flight?

No. I fly anywhere from 4,000-11,000. Full throttle and 2,500 RPM up
to 8,000, 2,700 RPM above that.

The subsequent two flights were 0.4 gph over and 0.1 gph over.
Close enough!

Yep. I figure you can't get it any tighter than that. The airplane
usually won't be level when you fuel it, or you won't fill it to
exactly the same place each time.
--
Dan
C172RG at BFM

EDR wrote:
* This is an outgrowth of the hot starting fuel injection thread

For those of you who have JPI or EDI fuel flow monitoring:
a) how many flights did you make before it was "calibrated"?
b) how much variance do you see from flight to flight?
b1) do you fly approximately the same altitudes/power settings each
flight?


My case:
I rent a 1978 Cherokee Six with an FS-450.
I flew it to Oshkosh 2002. Keeping track of flight and leg times on
each of the four tanks, I learned that the gauge was reading 25% too
high.
As I was more interested in flying than playing with the flow gauge, it
was not until last month that I finally got around to performing the
first correction.
As I said, it was reading high, so the correction is to add the
percentage of the currently indicated K-factor to that K-factor.
That done, a second flight was flown and the times and quantities
recorded. This time, the flow was 13% low.
Subtract this percentage from the current K-factor.
Go fly again, record time and quantity. High by 13%.

.... Correct that to 11%

Add that to the
current K-factor.
The subsequent two flights were 0.4 gph over and 0.1 gph over.
Close enough!

I had the FS-450 in my Tiger and it never required calibration. Was
accurate within 0.5 gals. And coupled to the GNC-300XL was a terrific
setup.

"EDR" wrote in message
...
* This is an outgrowth of the hot starting fuel injection thread

For those of you who have JPI or EDI fuel flow monitoring:
a) how many flights did you make before it was "calibrated"?
b) how much variance do you see from flight to flight?
b1) do you fly approximately the same altitudes/power settings each
flight?


My case:
I rent a 1978 Cherokee Six with an FS-450.
I flew it to Oshkosh 2002. Keeping track of flight and leg times on
each of the four tanks, I learned that the gauge was reading 25% too
high.
As I was more interested in flying than playing with the flow gauge, it
was not until last month that I finally got around to performing the
first correction.
As I said, it was reading high, so the correction is to add the
percentage of the currently indicated K-factor to that K-factor.
That done, a second flight was flown and the times and quantities
recorded. This time, the flow was 13% low.
Subtract this percentage from the current K-factor.
Go fly again, record time and quantity. High by 13%. Add that to the
current K-factor.
The subsequent two flights were 0.4 gph over and 0.1 gph over.
Close enough!

I have an FS450 on my Mooney. It is not hard to keep it calibrated.
All you have to do it compare the running totals when you fill your
tanks. The fact you are switching between tanks is generally not
relevant. The gauge/fuel flow turbine is accurate to within 2%. I
think the error induced from variabilities in filling is most of that.
It is an excellent instrument and safety item. I have no affiliation
to JPI.

Bob Miller
'65M20C - KCPS St. Louis MO

Subtract this percentage from the current K-factor.
Go fly again, record time and quantity. High by 13%. Add that to the
current K-factor.
The subsequent two flights were 0.4 gph over and 0.1 gph over.
Close enough!