To search for parts or accessories click on the SHOP tab (left) and search in the shop.
rotax 4-stroke - ignition & charging
912UL, 912A, 912F, 912ULS, 912S, 914UL and 914F Engines
The values indicated below can be checked on the engine installed in the aircraft, after detaching connections:
|
Generator coil (on stator) |
yellow – yellow |
0.1-0.8 ohms |
|
Generator winding |
yellow – grounding |
open circuit |
|
Charging coil (on stator) |
red – ground |
3.2-4.5 ohms |
|
Trigger coil |
green/white – blue/yellow |
115-123 ohms |
|
Trigger coil new* (with clamps) |
white/yellow – blue/yellow |
220-250 ohms |
|
Ignition coil, primary |
connection contact – ground |
0.1-0.4 ohms |
|
Ignition coil, secondary |
high voltage – high voltage |
6.1-6.7 kohms |
|
Resistance spark plug connector |
|
4.4-6.0 kohms |
|
Trigger gap old style |
0.4-0.5mm (16-20 thou) |
|
|
Trigger gap new style with clamps |
0.3-0.4mm (12-16 thou) |
|
* fitted in serial production, starting with design year 1995
|
ENGINE |
PLUG TYPE |
PART NUMBER |
PLUG GAP |
CHANGE INTERVAL S (unleaded mogas) |
CHANGE INTERVALS (avgas) |
|
912UL |
DCPR7E |
897255 |
0.6-0.7 mm (0.024 – 0.028 in) |
200 hours |
100 hours |
|
912A |
DCPR7E |
897255C |
0.6-0.7 mm (0.024 – 0.028 in) |
200 hours |
100 hours |
|
912F |
DCPR7E |
897255C |
0.6-0.7 mm (0.024 – 0.028 in) |
200 hours |
100 hours |
|
912ULS |
DCPR8E |
297940 |
0.6-0.7 mm (0.024 – 0.028 in) |
200 hours |
100 hours |
|
912S |
DCPR8E |
297940C |
0.6-0.7 mm (0.024 – 0.028 in) |
200 hours |
100 hours |
|
914UL |
X27EPR |
897257 |
0.6-0.7 mm (0.024 – 0.028 in) |
100 hours |
100 hours |
|
914F |
X27EPR |
897257C |
0.6-0.7 mm (0.024 – 0.028 in) |
100 hours |
100 hours |
All information provided here is correct at the time of publishing to the best of our knowledge, but Rotax recommendations may change at any time without our knowledge. It is the engine owners responsibility to ensure that the engine is fit for flight at all times. The information is provided here free of charge and with no obligation from us to the consumer. To ensure that you have the correct and most up to date information, you should refer to the current Installation, Operators and Maintenance manuals for your engine. The information provided here may not be valid for aircraft outside the UK. Click here for ConAir SportsTerms& Conditions, including website usage policy.
Always apply the correct heat sink paste to plug threads, see here
The wiring diagram is in the Installation manual for the engine which can be downloaded from the Documentation page at www.rotax-aircraft-engines.com
No, the ignition system is completely self generating and redundant (two separate ignition systems).
912 series engines - circuit A fires 1-2 top 3-4 bottom plugs
circuit B fires 1-2 bottom 3-4 top plugs
914 series engines - A fires all top, B fires all bottom plugs
Rotating magnets in the flywheel generate power as they pass over coil windings on the stator. The power generated is stored in capacitors in the SMD modules until the “triggers” send a signal to the capacitor which then passes the power to the secondary coils, which increase the voltage and send it, via the ignition cables, to the spark plugs.
Regulators need cooling - mounting in the engine bay is not a good idea and can cause premature failure.
The regulator output is 250W at 5500rpm. The output is less at cruise rpms. Do not overload the electrical system - items such as electrically heated clothing put high demands on the charging system.
914 engines rely on the electrical system for the fuel pumps. Improper installation or overloading of the charging system should be avoided.
Problem: Battery not charging (I.e. Low voltage)
Solutions: Remove the yellow wires and check the resistance between them is 0.3 - 0.8 ohms. If the resistance is infinity then you have a broken wire (open circuit). Re-install the yellow wires, run engine at idle and check output form yellow wires (should be 18-20 AC volts). Check output from B+ terminal or regulator, should be 14 DC volts - check the battery is charged - the regulator needs to be connected to a charged battery to energise it.
Problem: The generator is putting out AC volts but the Regulator is not putting out more than battery voltage - regulator is faulty.
Solution: Replace the regulator
Problem: The generator is not producing AC volts, the stator wiring is faulty.
Solution: Check / replace the stator wiring. Replace the stator.
Check grounds on Regulator & engine block before ordering new parts! Check your wiring if you fail more than one regulator - faulty regulators are not common but crossed wires are!
The “P” lead is the wire that grounds the Primary circuit of the ignition system, also known as shorting wire or ignition wire. The P lead connects to the main capacitor in the SMD ignition module. When the P lead is grounded by the ignition switch it prevents the module from firing as the electricity takes the easiest path to ground, instead of via the capacitor.
The ignition circuits are live when the engine is disconnected from the aircraft wiring.
The P lead needs to be shielded to prevent it acting as an arial and producing RF interference.
The P lead should never be connected to a voltage source, the ignition system does not require 12 V to operate.
965 358 (compatible with 4 pin Soft Start Miodule)
996 721 (compatible with 4 pin Soft Start Miodule)
996 726 (compatible with 6 pin Soft Start Miodule)
996 727 (includes Easy Start function) - identifiable by yellow label
It is extremely helpful to install a voltmeter to provide useful info on the charging system.