Advanced Ignition for the 21st Century - Installing the LASAR Electronic Ignition System - Part II

Advanced Ignition for the 21st Century — Installing the LASAR Electronic Ignition System — Part II By Harry Fenton July 2001 An overview of the LASAR® electronic ignition system was provided in the May/June 2001 issue of AMT. This...


Beginning the installation
Disconnect the battery from the aircraft electrical system to prevent accidental shock or damage to the LASAR controller while making the various wiring connections.
Install the M5340 manifold pressure fitting to the port found in the intake port of the most convenient cylinder. In most cases, it will be required to use a screw extractor to remove the pipe plug. The cylinder intake tube must be removed and the sump and cylinder openings must be plugged to prevent debris from entering the intake system. Once installed, connect the LASAR controller and the M5340 manifold pressure fitting together using low pressure flexible tubing.
Mount the controller on the firewall. Be sure that the rivnuts or any of the holes drilled to place the rivnuts or other mounting hardware will not interfere with the aircraft structure or other mounted components. Note the placement of the rivnuts and usage of the rivnut setting tool.
Remove the existing magnetos, mounting gaskets and ignition lead wires from the engine. Clean any residual gasket material from the mounting surface of the accessory housing. Remove the drive gears from the magnetos and install them onto the LASAR magnetos.
Align the crankshaft of the engine to the base timing angle on the compression stroke of cylinder number one. The base timing angle can be found on the engine data plate or in the engine Type Certificate Data Sheet.
Prepare the LASAR sensor and non-sensor magnetos for installation by inserting the T118 timing pin into the hole in each distributor block labeled "X." Ensure that the first step of the timing pin is fully seated against the face of the distributor block.
Install the sensor and non-sensor magnetos on the engine. Also, attach the magneto grounding straps to the engine accessory housing. Warning: LASAR magnetos or controller can be damaged if the ground strap is not properly attached to the engine. Remove the timing pins from the magnetos.

Timing the magnetos
Align the engine crankshaft to top dead center (TDC) on the compression stroke of cylinder number one. Reference the timing marks on either the front or the rear of the starter ring gear.
Connect the T300 Synchro-LASAR timing tool to the sensor and non-sensor magneto connectors. Complete timing instructions for both right and left rotation magnetos are detailed on the back label of the tool, so be sure to follow the instructions exactly as detailed in the SynchroLASAR instructions. Make sure fresh batteries are installed in the T300 prior to each use.
Once the tool is turned on, it is necessary to determine the sensor position in relation to the crankshaft TDC position. If the TDC light is off, rotate the housing of the sensor magneto counterclockwise (as viewed facing the magneto distributor block) until the TDC light just turns on, and tighten the magneto clamps to secure the magneto.
However, if the TDC light is on, then rotate the housing of the sensor magneto clockwise (as viewed facing the magneto distributor block) until the TDC light turns off. After the light turns off, rotate the sensor magneto housing counter-clockwise until the TDC light just turns on.
Next, rotate the engine crankshaft backwards until the "Sensor Bkr Pt" light on the SynchroLASAR turns on and then turns off. Slowly turn the crankshaft forward until the "Sensor Bkr Pt" light turns on. The engine crankshaft should be positioned approximately at the base timing angle position and the sensor magneto mounting clamps should be tightened to secure the magneto to the engine.

Non-sensor magneto
The non-sensor magneto must now be rotated so that the "Non-sensor Bkr Pt" light turns on to synchronize with the sensor magneto contact points. When the breaker point lights are synchronized, secure the non-sensor magneto to the engine.
After the magnetos have been secured, turn the crankshaft forward and backward throughout the TDC and advance firing positions to confirm the proper sequence of TDC and BKR point illumination. Once the timing is confirmed, install the ignition harness and new spark plugs.

Ignition switch configuration
The ignition switch must be configured so that both magnetos are on when the switch is in the both or start position because the LASAR controller will not function if either magneto is grounded during start. Most ignition switches simply require that a jumper lead from the right magneto terminal to ground be removed.

Placement of CHT probe
ImageA LASAR controller configured to sense Cylinder Head Temperature (CHT) requires input from an M5340-XX probe. The M5340-XX probe must be located in the hottest cylinder and is available with a dual output for K or J type CHT instrument systems should an existing CHT probe be located in the cylinder CHT well. To select the correct probe, consult SL1-96.
It is very important that the probe be positioned correctly in the well. The tip of the probe should contact the base of the well, so adjust the locknut accordingly to get the proper fit.
Installation of the enunciator light is straightforward. The light should be located so that it is readily visible to the pilot. Be sure to placard the light "DEFAULT IGNITION MODE" so that the pilot is aware that the LASAR system is in a default status and can take appropriate action.

Circuit breaker
Installing a cockpit-mounted circuit breaker that can be manually tripped is highly recommended. There are many instances when it is necessary to cycle power to LASAR during pre-flight checks, maintenance, or troubleshooting.

Installing the LVCH
ImageFinally, install the LVCH. The connectors of the harness must be lubricated using the supplied M5340 connector lubricant, but care must be taken not to contaminate the connectors prior to assembly. Ensure that the connectors snap together firmly and that the locking tabs have engaged. Connect the various color coded wiring connections as detailed in the schematic found in SL1-96. Be certain that the connections are secure as poor connections can cause intermittent signals to and from the LASAR controller. Never secure the LVCH to the high tension ignition harness. Try to route the LVCH at least two inches from the ignition leads.
LASAR is approved for operation with a minimum grade of 100 octane fuel. Placard the fuel tank filler opening with a label that indicates a minimum fuel grade of 100 octane.

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