Engine problem

[Bill Tugnett]

During a launch yesterday we lost power, revs dropped to ~ 3000 & was unresponsive to throttle. Full power was restored when we switched to Redundant. Post flight we were unable to start the engine normally, but it would start in Redundant. Not certain where to go with this - any advice would be appreciated. Thanks, Bill  (VH-FIG)

[hen...@holmkristensen.dk]

Hi

I can recommend to check the crankshaft tacho sensor.

The redundancy system has its own tacho sensor. 

You can put on a laptop to the engine controller and see if you are missing tacho signals from the sensor. 

Br

Henrik

Arcus no 58

[Bif Huss]

Hi Henrik,

I had a similar problem recently. In flight, the RPM's dropped to 4000 RPM, recovered and then dropped again. I selected redundancy and got full power from the engine. The problem was the throttle sensor. We replaced it and the engine worked normally. You do have to connect a laptop to the aircraft and run the Trijekt program to set the throttle sensor.

Hope that helps

Bif Huss s/n 207

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[Bill Tugnett]

Hi Henrik & Bif. Thanks for your suggestions. FYI our engine has ~ 15 hrs (was replaced after big end bearing seizure) & good compression, so we hope it's an ECU sensor problem. We're away from home base & it will be 12 days before we can use Trijekt. Some questions re Trijekt:-

Does program pinpoint sensor failure?

Are there any other sensors which might have failed?

In Redundant mode, should rpm be indicated? (Currently shows ---999)

Regards, Bill

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[Jorgen Thomsen]

Hi Bill

It might worth to check the inlet of the normal system fuel pump. Originally it has a small fine mesh filter insert on the fuel in side.

If it is clogged, you will have a fuel starvation in normal. Redundancy has its own pump, and probably a clean filter, with obviously full flow.

I have removed these filters, as filtration is done through several installed filters.

I regard it a big fault, these insert filters in the pumps are not mentioned in the Arcus MM.

Cheers Jorgen #061

[Bill Tugnett]

Thanks Jorgen. I recall being alerted to this potential problem earlier. Our filter was installed 3 years ago & I'm hoping, because of accessibility, it's not the problem. In any event the engine starts & runs in Redundant mode, which uses the same filter. I contacted Trijekt to see whether there is an English version of their diagnostic program, but they have declined, directing me to Solo.  Comments from Bif & another local pilot suggest the throttle position sensor may be the cause, so I'll be contacting Solo. At present we're at summer camp taking aero tows & using the engine in Redundant mode to stay airborne if necessary. Regards, Bill #132

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[Mark Zivley]

Bill,

I believe that the small filter being referred to is installed in the inlet of the two fuel pumps.  In which case, if the filter in the primary pump has become clogged, you will see a difference when you switch to redundancy.

My belief is that when the primary mode is operational, there is a fuel pressure sensor in the system (somewhere) and based on fuel pressure, the pump cycles on/off to maintain pressure, but does not run continuously.   I further believe that in redundancy mode, the fuel pump on that system ignores fuel pressure and does run continuously.

When you first power up the glider, you'll hear the primary fuel pump whine for a second or two until pressure builds up and then it goes quiet.   If you switch to redundancy I believe you will hear the redundancy pump running non-stop.

Mark

[Bill Tugnett]

Thanks Mark. I now understand the vulnerable filters are in the fuel pump inlets. That job will have to wait until I'm at home base next week. Rgds. Bill

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[Bill Tugnett]

Ran the Trijekt yesterday. Results indicate (to me) that the throttle position sensor is ok. Sent the figures to Solo - awaiting response. Rgds, Bill

On Tue, 14 Jan 2025, 5:53 am Mark Zivley, <markde...@gmail.com> wrote:

Bill,

Do you have a laptop that can run the triject program?   I would start with that.   If you find a sensor issue it might save a lot of work.   I bet you could do a screen shot and send that to solo.

Good luck,

Mark

markde...@gmail.com

On Jan 13, 2025, at 10:45 AM, Bill Tugnett <bill.t...@gmail.com> wrote:



[Jørgen Thomsen]

Hi Bill

The Redundancy is actually using a fresh filter in the Redundancy fuel pump, which is seldom used.

The pumps are easily accessible through the panel in the wheel well.

Cheers Jorgen 

Den 11. jan. 2025 kl. 12.59 skrev Bill Tugnett <bill.t...@gmail.com>:



Thanks Jorgen. I recall being alerted to this potential problem earlier. Our filter was installed 3 years ago & I'm hoping, because of accessibility, it's not the problem. In any event the engine starts & runs in Redundant mode, which uses the same filter. I contacted Trijekt to see whether there is an English version of their diagnostic program, but they have declined, directing me to Solo.  Comments from Bif & another local pilot suggest the throttle position sensor may be the cause, so I'll be contacting Solo. At present we're at summer camp taking aero tows & using the engine in Redundant mode to stay airborne if necessary. Regards, Bill #132

On Fri, 10 Jan 2025, 6:38 am Jorgen Thomsen, <jr_th...@hotmail.com> wrote:

Hi Bill

It might worth to check the inlet of the normal system fuel pump. Originally it has a small fine mesh filter insert on the fuel in side.

If it is clogged, you will have a fuel starvation in normal. Redundancy has its own pump, and probably a clean filter, with obviously full flow.

I have removed these filters, as filtration is done through several installed filters.

I regard it a big fault, these insert filters in the pumps are not mentioned in the Arcus MM.

Cheers Jorgen #061

<Filter pump.jpg>

<Filter.jpg>

[Bill Tugnett]

We have identified & corrected the problem. The control wire from the Trijekt to the front cylinder fuel injector was open circuit. When I removed the rubber boot from the plug, the control wire was fractured where it joined the pin (it is a crimped joint). So after ~ 64 hrs of engine time / slight vibration, the multiple strands had work hardened & fractured. The identification process was as follows: We had an MS Teams meeting with Marcus from SOLO, during which we had a laptop connected to the Trijekt. Marcus was able to view the Trijekt parameters & proclaim they were normal. Somewhat puzzled, he requested a day or two to discuss with his people & SH. Meantime the SH Australian agent suggested we try swapping the normal & redundant fuel injectors, as he felt the problem was due to a blocked injector. So I did this, but it made no difference. But it did prove two things - the actual injectors were not blocked & whilst swapping, with the fuel line open, I was able to establish that the Regular fuel pump was operating normally ie the basket filter in the pump inlet was not blocked. As promised Marcus came back suggesting two areas to investigate. The first was to track +12v to the Normal fuel pump & the second to check continuity from the Trijekt plug Pin 35 to Pin 10 on the front cylinder EFI plug & 17 to 11 on the rear cylinder EFI plug. As you now know, I chose the latter course & the glider is returned to normal service. I appreciate the input from the members of this group & hope the preceding will assist, should anyone else experience this problem. Regards, Bill

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