Bailey Moyes 912 Dragonfly, Maintenance Manual

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7.5 FloCalR (Return Fuel Flow Calibration)
This entry adjusts the scaling of the return fuel flow sensor. It is not used unless your fuel system
requires monitoring the outgoing and return fuel, using two fuel flow sensors. If only one flow sensor
is used, this setting is ignored, and will not affect the fuel flow calculation.
To adjust this setting for dual fuel flow installations, use the following procedure:
1) Set FloCalR to zero.
2) Turn on the electric fuel pump (with the engine not running), and verify a non-zero fuel flow
reading is displayed. Increase the value of the FloCalR in steps. As this setting is increased, the
displayed fuel flow should drop. Continue to increase this setting until the displayed fuel flow just
becomes zero. Use the lowest setting that results in a zero fuel flow display. A typical setting for this
entry is 128, but could vary by +/- 30%.
7.6 TachP/R - Setting for Correct Tachometer Readings
The EIS employs a sophisticated method of measuring engine RPM to provide 10 RPM resolution
independent of the number of pulses per revolution of the engine. To provide this flexibility, the
TachP/R is set to a code corresponding to the number of pulses the instrument detects per revolution of
the engine. To set this correctly for your engine, first determine how many pulses per engine
revolution will be generated, according to the following paragraphs, and set the TachP/R as indicated
by the TachP/R table. (The tachometer can not measure RPM from analog outputs that encode RPM as
a voltage level. This type of tachometer output is rare.)
Two inputs are provided to allow sensing the engine RPM from either of two sources. The EIS will use
tachometer input 1 when a tachometer signal is sensed. If tachometer input #1 is not providing any
RPM indication, the EIS will use tachometer input #2.
Each tachometer input has a corresponding TachP/R setting allowing them to be independently
configured. This allows the use of two dissimilar tachometer inputs, such as a magneto and an
electronic ignition input. The settings are identified as Tach1P/R and Tach2P/R, corresponding to each
of the inputs.
CAUTION: If there is any doubt about the accuracy of the tachometer reading, verify the reading using another
tachometer. Attempting to take-off with less than full power can be very dangerous. In general, if the EIS
tachometer reading is not erratic, and the TachP/R setting is correct, the tachometer will be accurate to 5 RPM.
7.6.1 Tach Connections to Magneto P-leads, Ignition Coils or Tach Outputs
These types of tachometer connections typically generate one pulse for every, or every other, spark
plug fired per revolution of the engine. Thus 4-cylinder engine will have 1 or 2 pulses per revolution,
while a 6-cylinder, 4-stroke engine will have 1.5 or 3. If you choose the wrong setting the tachometer
reading will be off by half or double the actual RPM. A 27 k Ohm resistor must be connected between
the instrument and the mag P-lead as shown in figure 7 to protect the mag from being turned off by a
failure in the instrument.
A magneto or ignition test is commonly performed before each flight for airplanes that include dual
ignition systems. This test requires turning off each ignition system, and verifying that the engine will
function on the remaining ignition system. Two tachometer inputs are provided to allow sensing the
engine RPM from either of two ignition systems so that the RPM indication is not lost during the
magneto test.. The EIS will use tachometer input 1 when a tachometer signal is sensed. If tachometer
input #1 is not providing any RPM indication, the EIS will use tachometer input #2.