Faulty Coil?
in 912 / 914 Technical Questions
10 years ago
Following the seizure of my 912 UL, I replaced the engine with a new 912 UL2.
The engine started easily and ran smoothly during initial runups and dynamic propeller balancing. Yesterday I decided to make my first flight with the new engine. The Pipistrel runup check calls for checking the ignition at 3,000 RPM. Switching off the B switch I noted an RPM drop of around 150 RPM. Switching off the A switch I saw about 550-600 RPM drop. I decided not to fly.
Back at the hangar to troubleshoot, I noticed that, when ignition B was shut off, cylinders 3 and 4 showed significantly lower EGT than when both ignitions were switched on. As another test, I removed the plug wires from the upper plugs on cylinders 1 and 2. On the next check, when I switched off the B ignition, then engine stopped. This indicates to me that the coil feeding the lower plugs on 3 and 4 is not firing the plugs.
It seems to me that this coil is bad. Or, does each ignition module have separate circuitry to trigger each coil and is it possible that part of the module is bad?
Since the engine is brand new and under warranty, I should be able to get free replacement parts through Lockwood (I bought the engine from them). I'll call them in the morning and see what advice they can give.
The engine started easily and ran smoothly during initial runups and dynamic propeller balancing. Yesterday I decided to make my first flight with the new engine. The Pipistrel runup check calls for checking the ignition at 3,000 RPM. Switching off the B switch I noted an RPM drop of around 150 RPM. Switching off the A switch I saw about 550-600 RPM drop. I decided not to fly.
Back at the hangar to troubleshoot, I noticed that, when ignition B was shut off, cylinders 3 and 4 showed significantly lower EGT than when both ignitions were switched on. As another test, I removed the plug wires from the upper plugs on cylinders 1 and 2. On the next check, when I switched off the B ignition, then engine stopped. This indicates to me that the coil feeding the lower plugs on 3 and 4 is not firing the plugs.
It seems to me that this coil is bad. Or, does each ignition module have separate circuitry to trigger each coil and is it possible that part of the module is bad?
Since the engine is brand new and under warranty, I should be able to get free replacement parts through Lockwood (I bought the engine from them). I'll call them in the morning and see what advice they can give.
