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By Sooty25
#1808935
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.


Thing is, they all have potential single points of failure, and whilst d-motor could , and may well do in the future, have fitted duplicate senders, Rotax can't duplicate the gearbox they need as a result of opting for small cc's combined with higher revs.

Having said that, the A65 at the start of the thread only had one carb and one fuel pump.

The origins of dual magnetos probably only stems from how unreliable they were, I doubt they started fitting them for the tiny flame path gains from two sparks!
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By Kemble Pitts
#1808941
Quite.

Almost every system will have a single point of failure somewhere, the key point is the probability of that failure. That and the consequence of that failure - the Failure Condition.

The crankshaft could break, with less than ideal consequences, but its not likely to happen.
Last edited by Kemble Pitts on Tue Nov 17, 2020 8:59 am, edited 1 time in total.
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By Charliesixtysix
#1809359
Kemble Pitts wrote:Quite.

Almost every system will have a single point of failure somewhere, the key point is the probability of that failure. That and the consequence of that failure - the Failure Condition.

The crankshaft could break, with less than ideal consequences, but its not likely to happen.


Curiously enough I saw Gerald Cooper suffer exactly that, on a sub 50hr since rebuild (new?) Lycoming - he was midway through a display when there was a marked change in engine note and he turned the figure into a glide approach to his own hangar at the end of the runway at Wickenby.

Very neatly done it was too. :thumleft:
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By Sooty25
#1809445
CloudHound wrote:Isn't there a weight and balance issue to be taken into account when swapping out a Ly/Cont for Rotax?


912 is lighter than an A65, so just add lead!
By The Kissimmee Bum
FLYER Club Member (reader)  FLYER Club Member (reader)
#1811249
Sooty25 wrote:
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.


Bu**er the dual sensors. Just give us the override!
By Wabash
#1830573
Whilst it's an obvious idea for those that love a project, ultimately depending on aircraft type it could devalue the aircraft or diminish the number of future buyers so that need factoring in to how much it really will save you overall. This is almost always the case with many classic cars as they become old drop in value people don't want to spend what it costs to keep them so they chop the engines out in goes something else. As the values rise nostalgists enter the market and they don't want a non standard one off homebrew and they have the money to spend. Just make sure it's easily reversible and keep the original engine in a crate so the nostalgists might be still interested in buying it in future.

Best thing is to set up a Co operative business to quality blueprint restore these lovely old engines you should get plenty of business :lol: