Username Protected wrote:
Keep it simple and copy it.
Not particularly that simple:
Attachment:
tbm-fuel-sys-1.png
Quote:
Great system with no issues.
There's a lot to know about it:
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AUTOMATIC TANK SELECTOR (Figures 7.7.2 and 7.7.3)
Automatic tank selection allows, without pilot’s intervention, feeding the
engine from one tank or the other in predetermined sequences. These
sequences depend on airplane configuration (ground, in--flight, fuel low level
CAS messages appearance).
Automatic tank selection system comprises an electronic sequencer, an
actuator attached on the fuel unit, ”FUEL SEL” two--position selector (AUTO,
MAN) and ”SHIFT” knob located on ”FUEL” panel.
To operate the automatic selector, set ”FUEL SEL” switch to AUTO position
and manual selector to R or L.
Selector operation
When the system is operated, ”AUTO SEL” CAS message disappears ; the
sequencer chooses a tank (R or L) and through the actuator, positions the
fuel unit selector on the selected tank. The sequencer controls the time
during which the selected tank will operate. This time varies, depending on
airplane conditions.
Airplane on ground : tank is changed every minute and 15 seconds.
Pre--MOD70--0402--28
Airplane in flight : tank is changed every ten minutes, as long as a fuel low
level CAS message does not appear. When the first low level CAS message
lights on, the sequencer immediately selects the other tank. The selected
tank will operate until the second low level CAS message lights on. When
both low level CAS messages are visible, the sequencer changes tanks
every minute and 15 seconds.
Post--MOD70--0402--28
Airplane in flight : tank is changed every five minutes, as long as a fuel low
level CAS message does not appear. When the first low level CAS message
lights on, the sequencer immediately selects the other tank. The selected
tank will operate until the second low level CAS message lights on. When
both low level CAS messages are visible, the sequencer changes tanks
every minute and 15 seconds.
NOTE :
The manual selector is driven by the fuel unit and is positioned on R or L mark
corresponding to the tank selected by the sequencer. Therefore, the pilot
continuously knows the tank which is operating.
Test for system proper operation
”SHIFT” push--knob allows the pilot to test system proper operation anytime.
When the system operates, the fuel tank is changed when ”SHIFT”
push--knob is pressed once.
If airplane is on ground or in flight, low level CAS messages not visible, the
new selected tank remains operating and a new sequence is initiated.
NOTE :
This procedure allows the pilot to preferably choose the tank from which he
wants to take fuel.
In all cases, proper system operation is indicated by rotation of the manual
selector.
Setting ”FUEL SEL” switch to MAN position or setting manual selector to OFF
position leads to system de--activating and appearance of ”AUTO SEL” CAS
message. ”AUTO SEL” CAS message also lights on when order given by the
sequencer has not been executed after 12 seconds.
AMBER WARNING CAS MESSAGE
“AUTO SEL” ON
Indicates there is no more automatic control mode running
1 -- ”FUEL SEL” switch ................................. AUTO
If it is on “AUTO”, failure is confirmed
2 -- ”FUEL SEL” switch .................................. MAN
3 -- Select tanks manually as required
CAUTION
MAXIMUM UNBALANCE IS 15 USG
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Appears the switching time in flight was lowered to 5 minutes by a mod, and I find it odd it switches every 75 seconds on the ground. I surmise they want roll trim to be very near neutral for takeoff?
Mike C.