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By Kemble Pitts
#1808317
... and, as I said, the hardware and software are non-certified so the 'errors' might not be fixable as they could be fundamental design issues.

When the D-Motor put me in a field (twice) the Belgian designers were not able to come up with a convincing reason and thus no convincing fix.
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By Sooty25
#1808327
Kemble Pitts wrote:... and, as I said, the hardware and software are non-certified so the 'errors' might not be fixable as they could be fundamental design issues.

When the D-Motor put me in a field (twice) the Belgian designers were not able to come up with a convincing reason and thus no convincing fix.


A bit like Boeing 737 Max then! :lol:
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By lobstaboy
#1808517
That makes two of us who've had "interesting" experiences with the D- motor. Different ones in my case and didn't end up in a field, but could have done...
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By Kemble Pitts
#1808596
lobstaboy wrote:That makes two of us who've had "interesting" experiences with the D- motor. Different ones in my case and didn't end up in a field, but could have done...


Go on...
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By Sooty25
#1808644
Kemble Pitts wrote:
lobstaboy wrote:That makes two of us who've had "interesting" experiences with the D- motor. Different ones in my case and didn't end up in a field, but could have done...


Go on...


I'm interested to hear what the symptoms are in all the events, just out of curiosity.

I do wonder if the software engineer is a pilot. We tend to have different priorities to automotive users, automatic "limp mode" isn't always good!
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By Kemble Pitts
#1808806
OK.

I was giving a lesson in a D-Motor powered Sherwood Ranger. Rather a hot day. We'd drifted down to about 600ft AGL so I asked the student to apply full power and climb to 1500ft AGL and establish us in the cruise. At 1500 ft he reduced power to a cruise setting but the engine ran down to tick-over. I asked if he'd done that? No.

I have control.

Moving the throttle had no effect. So we are 'landing out'. Luckily we were within gliding range (think man-hole cover on edge) of a farm strip: so in we went.

I called the CFI and we waited an hour or so for him to arrive with some cold drinks. We looked at each other with that 'I bet it'll just start and run now' feeling - and it did. Obviously it had cooled down and had a bit of a 'think' and decided things were not as bad as it had thought!

After a satisfactory ground run I elected to fly it solo the three miles or so back to base, keeping a forced landing option open all the way.

The same thing happened that afternoon (nooo, I hear you say). This time I was deliberately near that farm strip!! Same thing again, same outcome.

I'd had enough by then.

I reckon it was a sensor of some sort getting its knickers in a hot twist.

D-Motor in Belgium didn't come up with anything convincing.

On the flip side, when its working it runs smoothly and unobtrusively.
By romille
#1808809
That is the problem with modern engines, everything is absolutely fine, but a sensor decides to have a wobbly, the ECU thinks there is a major problem, so it initiates limp mode to protect the engine. It is bad enough on a busy motorway, but there is so much more potential for disaster in an aircraft flying relatively low.
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By Sooty25
#1808827
@Kemble Pitts that is very interesting.

I've just read the D-motor installation manual and I think I've spotted a flaw in the design. They have gone to all the effort of installing dual ECU's, yet both ECU's run off the same engine sensors. A faulty pressure or temperature sensor would have the same effect on both ECU's.

A duff/intermittant sensor could be the cause of the problem.

The next issue is how the pilot is allowed to deal with it. With an A65, a low oil pressure indication for example, can be accepted and overridden by the pilot. He can elect to "nurse" the engine to get to a suitable airfield even if he trashes the crank in the process. The same doesn't appear to be the option here, the d-motor just goes limp and you are landing regardless.

The d-motor needs dual sensors to prevent a single point failure. It also needs an "override" button to allow the ECU to use a default setting allowing the pilot the option to nurse it down in the event of a parameter going out of range.
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By Bathman
#1808829
Are we not overlooking the Rotax 912 here. Proven to be be very reliable and good for 4000+ hours. I don't hear of any real problems of maintaining the complexity of its 'modern' ignition system.
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By Dusty_B
FLYER Club Member  FLYER Club Member
#1808887
The problem with 912s is not knowing if it will still be attached next time I get to the aeroplane. I guess that is an indication of how good they are considered to be!!
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By Kemble Pitts
#1808903
Sooty25 wrote:I've just read the D-motor installation manual and I think I've spotted a flaw in the design. They have gone to all the effort of installing dual ECU's, yet both ECU's run off the same engine sensors. A faulty pressure or temperature sensor would have the same effect on both ECU's.


That is interesting; a feature that would never survive a decent System Safety Assessment during a pukka certification process.
By Boxkite
#1808913
Kemble Pitts wrote:
Sooty25 wrote:I've just read the D-motor installation manual and I think I've spotted a flaw in the design. They have gone to all the effort of installing dual ECU's, yet both ECU's run off the same engine sensors. A faulty pressure or temperature sensor would have the same effect on both ECU's.


That is interesting; a feature that would never survive a decent System Safety Assessment during a pukka certification process.

It survived a check-over by the FAA on the 737 Max....
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By Kemble Pitts
#1808925
Boxkite wrote:
Kemble Pitts wrote:
Sooty25 wrote:I've just read the D-motor installation manual and I think I've spotted a flaw in the design. They have gone to all the effort of installing dual ECU's, yet both ECU's run off the same engine sensors. A faulty pressure or temperature sensor would have the same effect on both ECU's.


That is interesting; a feature that would never survive a decent System Safety Assessment during a pukka certification process.

It survived a check-over by the FAA on the 737 Max....


Note that I specified a 'decent System Safety Assessment'! :D
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By A4 Pacific
#1808930
It survived a check-over by the FAA on the 737 Max....

Wasn’t the problem that the FAA felt insufficiently qualified for such a “check-over”? So they delegated that step to the manufacturer?