Advanced Ignition for the 21st Century — Installing the LASAR Electronic Ignition System — Part II
By Harry Fenton
An overview of the LASAR® electronic ignition system was provided in the May/June 2001 issue of AMT. This article, the second and last in the series, outlines a LASAR installation recently completed by Unison.
The subject aircraft of this installation, a Wag-Aero Sportsman, is an amateur built rendition of a Piper PA-14 Family Cruiser, somewhat of a four-place version of a Piper Cub. While not representative of your garden-variety aircraft, the basic LASAR installation techniques are the same for most other single engine aircraft listed on Unison’s LASAR STCs. The installation will require about 3-4 hours of shop time, while LASAR systems with extra features such as CHT interface and cockpit enunciator lights will require about 5 hours or so. Keep in mind, advance planning and preparation will ensure that the installation will be accomplished in a timely manner.
The T-300 SynchroLASAR® is the only special installation tool required, but there are a few other commonly available tools that certainly speed the installation along. A #8 screw extractor, 1/4-in. drill bit, and a rivnut tool capable of inserting 10-32 rivnuts will prove to be significant time savers.
Prior to the installation, obtain the latest copy of LASAR Service Letter SL1-96 and review it thoroughly to understand parts selection and the installation procedures. Once again, pre-planning is key and having all of the major LASAR components, circuit breaker, hardware, pressure tubing and other incidentals on hand at the time of installation will help to ensure a trouble-free installation experience.
The open area on the firewall of the Sportsman is tight, but a location for the controller is found on the lower right side (as referenced from the pilot’s perspective). Preferably, the controller should be mounted with its manifold pressure port and electrical connector pointing downward, left, or right to prevent the connector from becoming contaminated. Given the location of the exhaust, the controller will be mounted so that the connector faces right.
Allowing for adequate slack, but not so much that there would be excessive length to the low voltage control harness (LVCH – sometimes called an "LH" harness), the distance from the back of the controller LVCH connection to the back of the left and right magnetos is measured. Using the LVCH selection chart found in the SL1-96, the correct length and part number for the LVCH harness are identified. In this installation, the correct part number is LH1004-17. Also, for this installation, we had the advantage of already having the controller and magnetos before measuring the correct length of the LVCH. To determine the correct length of the LVCH before procuring any of the LASAR components, first determine the exact controller location and orientation on the firewall. Then measure from the planned location of the controller’s electrical connector to the rear housing of both the left and right conventional magnetos. Follow the remaining instructions and chart in SL1-96 to identify the appropriate LVCH part number.
Based on a review of SL1-96 and the pre-work just described, the components ordered for installation on the Sportsman and Lycoming O-320-E3D combination can be found in Table 1.
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.
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
A 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.
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
Finally, 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.
Confirm that the master switch and ignition switch are in the "Off" position and reconnect the battery to the aircraft electrical system. When power is applied, the LASAR enunciator light should be illuminated and will go out after the first revolution of the engine. It should stay off once the engine is running. Ground test the LASAR system in accordance with the Pilot Operating Handbook. Conduct a standard run-up and check the left and right magneto for operation. The engine will run in backup on each individual magneto, and when switched back to both, will operate in backup for 20 seconds and then automatically switch to LASAR mode and extinguish the enunciator light.
Before releasing for flight make all appropriate logbook entries and complete an FAA Form 337 to record the STC installation. A Flight Manual Supplement is part of the LASAR system and must be attached to the Pilot Operating Handbook.
From the standpoint of recurring maintenance, LASAR requires a standard 100-hour external inspection to confirm that the connections and component mounting are sound. An internal inspection of the LASAR magnetos is recommended at 500-hour intervals.
Troubleshooting can be accomplished using the T300 SynchroLASAR and T232 communications cable. The T232 connects to the LASAR controller and can be linked to a laptop computer or PC to provide real-time operation and diagnostics data. If a fault occurs, a code will be displayed on the diagnostics screen that will provide an accurate diagnosis of the fault condition. Consult Unison before using the T232 communications cable.
This article has gone through the basic procedures for installing a LASAR electronic ignition system. For complete installation information or troubleshooting guidance, you can contact an authorized LASAR distributor or Unison Industries to obtain the L-1500 LASAR Master Service Manual.
Quantity Part Number Description 1 L1526BLASAR Installation and STC package1LC1011-01Controller14771Sensor magneto14770Non-sensor magneto1 LH1004-17 Low Voltage Control Harness (LVCH) 1 M4001U Slick™ ignition harness with blue lead wires* 8 UREM40E Autolite® Aviation Spark Plugs 1 M5340-03 Dual point CHT probe 1 M5470-01 Enunciator light receptacle 1 M5470-14 Light bulb 2 M3426 Magneto gasket 1 10 amp manual trip circuit breaker 4 feet 1/4-in. ID low pressure hose 4 10-32 Rivnuts *(Note: Only Slick harnesses are approved for use with LASAR.)
About the author
Harry Fenton is Manager of Customer Support for Unison’s Piston Engine Products. He is a pilot and an aircraft technician with an A&P and IA. You can reach Harry at Unison’s Rockford, IL facility at (815) 965-4700 or at firstname.lastname@example.org