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First experience of possible vapour lock

A very British view.

Bosco, just because the UK is pretty well unique among the “old” European countries in not getting deeply offended at any criticism, this is not a reason to write this sort of thing!

Imagine what would happen here if somebody non German wrote “A very German view”.

The rest of your post i.e.

Half of the German C150/C152/C172/C182/PA28/AA5A/DR400 fleet is operated on mogas, and almost none of them are switched to Avgas during high summer. and nothing bad happens.

is a good data point. Why not just stick to that?

Administrator
Shoreham EGKA, United Kingdom

Actually I think he has a point. The British always think of themselves as a premier state for aviation. Who always know best what we really should do is look at the evidence.

For decades the dangers of mogas have constantly been published in the UK. Officially from the CAA, in PPL books and I even remember reading about the perils of 4 star petrol in pilot magazine way back in the late 80’s.

As it turns 4 star petrol was probably an ideal fuel for many aircraft and their engines. The chipmunk POH said any good motor spirit of 66 octane or more. Yet the CAA mandated we had to poor avgas in the thing.

I’ve never operated mogas in 40 degrees but I’ve flown jodels in 30 degree heat. Without problems.

Last Edited by Bathman at 12 Aug 19:23

" had issues with Mogas flying Turbulents, they have WW1600cc Beettle car engines and do take Mogas by default, obviously those cars don’t drive at 6kft, vapour lock"

The european mountain roads are litterally littered with stranded cars – in winter because they do not have chains, in summer because vapour lock.

T28
Switzerland

The Petersen Mogas STC has, if I recall correctly a limitation on max altitude and a max fuel temperature- from distant memory 26C without a geographical limitation.

EHLE / Lelystad, Netherlands, Netherlands

boscomantico wrote:

Half of the German C150/C152/C172/C182/PA28/AA5A/DR400 fleet is operated on mogas, and almost none of them are switched to Avgas during high summer. and nothing bad happens.

Maybe something to do with quality control of Mogas distribution in Germany vs UK? rather than STCs or octane/vapour/ethanol/icing concerns
The data for some vintage accidents & incidents I saw had 5/30 with purchased directly super market fuel pumps…

I don’t think it is a “UK view only” but surely the restrictions on Mogas usage are tougher than those in Germany
But I guess it has to do with obtaining as cheap “non-CAA LAA Permit” than using cheap low quality fuel

http://www.lightaircraftassociation.co.uk/engineering/Mogas/SIoBiA.pdf

Having thrown anything in a Rotax TMG and flew it in any conditions, I think I am well informed which better fuel to put in which engine I may change my mind if I can fly a Lyco C172 on SP95 in 40C deg for 50 hours but some scepticism is healthy after all they don’t sell German Mogas in the UK

Last Edited by Ibra at 12 Aug 19:45
Paris/Essex, France/UK, United Kingdom

The British always think of themselves as a premier state for aviation.

That’s true only for the old farts which used to populate the CAA and its offshoots like the LAA. But it isn’t unique; you will find the same sense of superiority in every one of the “old country” national CAAs.

I don’t see any such general view among the UK GA community which actually flies.

As it turns 4 star petrol was probably an ideal fuel for many aircraft and their engines. The chipmunk POH said any good motor spirit of 66 octane or more. Yet the CAA mandated we had to poor avgas in the thing.

The difference could be due to any number of things e.g. dodgy car petrol in modern times (I know mogas isn’t forecourt petrol but a lot of people with small engined machines – basically ones where jerrycans can be filled up practically and transported – do fly mogas-certified engines on car petrol). The Chipmunk POH was written half a century earlier when car petrol was much cleaner. Or fuel system layout. This stuff is highly type specific. Many mogas related threads – example which are not specific to the SR22.

Regarding MarkW’s post, which is about an SR22, does the SR22 POH say anything about this? If it doesn’t, I would think there is some problem with the plane, otherwise this sort of thing should have some to light much earlier. SR22s are everywhere and have been for many years. Central Spain has some too and that gets close to +50C in the summer. For example it might be a defective engine driven fuel pump; I had one of those. It was discovered when a number of accessories were replaced as a precaution because there was a “funny noise” and that pump is so cheap (c. $300) that chucking it out was a no-brainer. Mine had a broken spring in it, and this happened roughly 1 year from new.

The Petersen Mogas STC has, if I recall correctly a limitation on max altitude and a max fuel temperature- from distant memory 26C without a geographical limitation.

Is that for an SR22? This stuff is highly fuel system layout specific. Incidentally, a +26C max fuel temp would be pretty useless in Europe if anybody actually obeyed it.

Administrator
Shoreham EGKA, United Kingdom

The Petersen Mogas STC has, if I recall correctly a limitation on max altitude and a max fuel temperature- from distant memory 26C without a geographical limitation.

You mean as approved by the FAA, or the LBA? No.

The CAA did impose something like that in their approvals. (That‘s what was referred to with the „British view“.)

Worthwhile reading here and here.

Last Edited by boscomantico at 12 Aug 20:10
Mainz (EDFZ) & Egelsbach (EDFE), Germany

There is of course no mogas STC for the (any) SR22.

It (vapour lock) does happen. I have had such event myself just 4 weeks ago, in a Reims Rocket, in 30+ degrees.

Mainz (EDFZ) & Egelsbach (EDFE), Germany

Was that an in-flight engine stoppage, or something which happened on the ground? How was it solved.

Administrator
Shoreham EGKA, United Kingdom

In-flight (just after departure), surging, cured by flipping on the boost pump.

Mainz (EDFZ) & Egelsbach (EDFE), Germany
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