I think it might be taking things a bit far, unless I have missed something, to call the B23 incidents posted on here as being either accidents or dramatic losses of power.
Certainly, these were not the case in the 2 I posted even if one was called up as a Pan Pan and the other as a Mayday.
In both cases, despite a smell of burning they landed safely. And although the fire service was in attendance, on neither occasion were they needed.
I have no clue why UL91 would perhaps cause a power loss where UL95 does not.
Although I understand that this is a preliminary finding from BRM. IMO we need further information.
I’m pretty sure all aircraft types mentioned in the original report (first post in this thread) have an aux fuel pump. The one in the B23 functions properly. Have had some departures in the middle of a heat wave with a heat-soaked engine without missing a beat. 95 automotive gas.
Hi guys,
my club in France is operating a B23/912 and we had 2 engine failures due to detonation on 2 different brand new engines at 54 and 48 hours engine time respectively.
We use UL91, as per B23 flight manual and Rotax reccomendations.
The SB issued by BRM against UL91 has taken everybody by sirprise, including Rotax that wasn’t aware of it.
Strangely, some major engine failures that required engine replacement or repair occurred with SP98 (mogas).
Other operators run their B23 with UL91 with no problems at all….
I just published a post in the Aircraft section (https://www.euroga.org/forums/aircraft/15381-bristell-b23-loss-of-power).
Thanks. However, these are clearly two kinds of different problems. The cases discussed here (not only for the B23) are cases where the engine temporarily became rough and/or partially lost power. Clearly a fuel supply problem.
Your cases seem mechanical, with damage, oil loss and all.
Either way, it does not project well on BRM and the B23.
Well, I’m in constant exchanges with Germany’s LBA.
They teamed up with Swiss BAZL and Austro Control to form a task force and draw Easa’s attention on Rotax’s 912 reliability.
There clearly is a problem with B23, Aquila and some Tecnam models…..
Aquila co-operates with the investigations, but the other two don’t.
And Rotax is not helping either.
It’s a serious, big mess.
I guess you already seen this one: https://rexffa.fr/PublicReport/Details/2829
Something to do with carburator float apparently.
I think it is a fuel supply problem. I don’t know the issues regarding the Aquilas, but i can remember an issue of a rough running engine in a B23 during a descend with idle power. With a setting of 15 inHg MAP and 5300 RPM the engine was running smooth again.
A 912 S2 installed in a Tecnam 2008 of my flying club shows no problems using mostly UL91. We had one major issue due to a broken spring of an exhaust valve. But i don’t think that a damage of this kind may be caused by detonation.
Xtophe wrote:
I guess you already seen this one: https://rexffa.fr/PublicReport/Details/2829
Something to do with carburator float apparently.
Yes, I’m aware of this. I just talked with the instructor involved in this incident.
The initial analysis shows that this is related to delamination of the inner part of the carburetor.
A further update.
First of all, yes, BOTH our aircraft experienced problems on the same weekend. However, what was reported was “only” roughness (and no real power loss as such).
We are aware of other B23s in Germany that have the same issues.
Rightly so, our club managers are not at all convinced by the UL91 story, to put it mildly. Anyway, for now, the use of UL91 AND mogas has been banned by club order. So 100LL it is for now. The aircraft are back in service, but of course, faith in these is dwindling.
Rather, since the problems always seem to occur on climbout, with the aux fuel pump ON, our shop’s suspicion is more that the problem has to do with having TOO HIGH a fuel pressure. To me, that sounds more plausible.
One B23 incident of power loss in France occurred during the approach. It is reported in this weeks FFA Rex.
There are now thoughts that there could be problems with some carb floats. But it seems to be proving difficult to be sure.
