OK - I have been teaching the Lear 23/24 and 25 systems, many moons ago.
Shall we say nearly... 40 years ago...? Early 1970 era...
And I continue to fly Lears presently, 31A, and 35/36.
I just stay "barely current" on types.
xxx
Here are some facts about the Lear fuel systems -
NB - The Learjets s/n to 23-029 did not have JET PUMPS... (Elec. Pumps only).
xxx
(1)
Jet pump switches (L and R) control the opening/closing of the MFCV...
MFCV = Motive Flow Control Valves, 28VDC, wired (spring loaded) to OPEN position.
IN CASE of 28VDC failure > MFCV fail OPEN (feeding the respective engine).
(2)
IN CASE of a "LOW FUEL PRESS" light ON (less than 2 PSI pressure) -
Select L (or R) Jet Pump OFF, turn SEFP (Standby Electric Fuel Pump) ON...
If in cruise, and this low pressure light is ON, descent to or below FL250.
This will permit RAM AIR to pressurize wing/fuselage tanks to "above .25 PSI".
High VMO suggested to keep pressure.
(3)
What can cause a L (or R) MFCV to close...? -
(a) Related L (or R) Jet Pump Switch OFF (powering MFCV closed), or...
(b) Engine start switch L (or R) to START position.
(4)
There are no moving parts in a jet pump... they "never fail"...
If "motive flow pressure" is present, "Jet Pumps" will be operating.
(5)
In Learjets equipped with TIP TANKS, (23/24, 25 and 35/36), note that -
Bottom 1/2 tip tank fuel NOT available IF related L (or R) MFCV is closed, or tip tank jet pump failed.
(6)
Procedures - L (or R) LOW FUEL PRESS light ON =
(a) select L (or R) Standby Electric Pump ON, and, if light still ON -
(b) select L (or R) Jet Pump OFF...
(7)
L (or R) Fuel Jettison (DUMP) available from TIP TANKS only (if installed).
xxx
The above are all my notes for the Learjet fuel system...
... And stop laughing at me if I flare 30 feet above TDZE... (sorry, old 747 landing habit).
Still dont know why the boss (airline CEO) want ME to fly him...?
By chance I have a F/O more competent than me.
xxx
Happy contrails