Microlighters

I have just had my trike's engine serviced. I bought the trike with 158 main jets, but when the AP saw this he freaked, stating that this can burn a hole in the piston as it is running too lean. I had to purchase 165 main jets which will be fitted. The Rotax agent (Comet) indicated 158 mains at altitude and 165 mains at sea level. I have since spoken to other service guru's and I am getting different stories. Two indicated that 158 will burn holes, but the others are running 158's and have been for more than 1200 hours. Which is preferred ?

158 at altitude and 165 at the coast.
Tell your AP to go back to school............ or tell him to phone me and I'll tell him to go back to school

Duck Rogers wrote:158 at altitude and 165 at the coast.
Tell your AP to go back to school............ or tell him to phone me and I'll tell him to go back to school

And the 503?

German wrote:And the 503?

158 at sea level and 155 at high altitude

Duck Rogers wrote: or tell him to phone me and I'll tell him to go back to school

Aag he'll just' DUCK',

Thanks guys, I will not want to start a war here
Fit the 165's, get it signed out and then put the 158's back? Is this ethical, both uses the same needle.

Try this site, it seems to have all the answers.....If not Morph or Duck will be able to help.

http://www.ultralightnews.ca/bing/bingjetchart.html

Later

Raymonvt wrote:Thanks guys, I will not want to start a war here
Fit the 165's, get it signed out and then put the 158's back? Is this ethical, both uses the same needle.

There's a possibility that, IF something happens and you prang the plane, the AP may turn around and say that he signed it out with 165's and now there's 158's in the carbs? Your Insurance MAY not pay out.
But you don't have to go that route. Your AP really doesn't know what he's talking about
Refer him to the following chart and if he still doesn't want to sign it out then get another AP.

The example given in the chart is for a size 158 at sea level (Rotax 503). Just apply the numbers for the 582 and get the correct answer

Example: I would say 5500' at 25 deg C = 94.5 (D2) and 0' at 25 deg C = 99.5 (D1)
Now D2 divided by D1 = 0.9497 x 165 (main jet at sea level) = 156.70 rounded off to the next higher available main jet = 158

And here's all the jetting and needle sizes for the different Rotax 2 strokes AT SEA LEVEL

Duck, thanks a lot !
I will get the AP to sign it out on 165's and then ask another AP to sign back the 158's.
The AP working on the aerie have already had a "talk" with the Rotax agents saying they do not know what they are talking about.
I am tending towards the 158's at altitude and 165's at sea level.
Another stupid question, should I put the aerie on a trailer to the coast over easter, can I change to 165's for thr period, or does a AP have to sign it out too?

I'm not sure about that. From what I remember about the "self maintenance" saga that was going on, I think an AP has to do it, if you want to stay "legal". Maybe someone else can help us out here.
IN MY OPINION, changing to 165's when flying at the coast, is the right thing to do,

Raymond that AP bases his recommendation on 30 years of experience not just on 'sommer'. Although the theory is sound and yes it is the 'recommended' altitude jets he has seen many failed engines with melted pistons on the 582's hence the recommendation. I have never seen a failed 582 that ran slightly rich but have seen several damaged engines becuase of unning lean. Honestly he is a very well respected guy and he certainly does not need to go to school.
Regards

Stephan,
Thanks for the input, I don't believe it is a crime wanting to get a second opinion though, the AP is aware of this. I am not and have not acted unethically, my safety is not your responsibility, also we as users always end up paying for other's mistakes should they make mistakes, and it can happen that we do not pay with money.
The AP persist 165 is the way to go, if it means a little more fuel and safer flying I am happy to do so, provided the logbook is signed by him.
If the AP deviate from "the book" I am entitled to query that, why do the AP's deviate from the Rotax Agent specifications, we have to trust them with our lives, this is no laughing matter.
My concern is still the difference in opinion between individuals all authorised to do aviation maintenance.
I have discussed this with the CAA inspectors as well, more I cannot do.

Guys, just a little feedback if you are interested.
I have fitted the 165 main jets (the AP did), new needles etc. Needle position 2.
I flew the aerie for an hour this morning (solo) burnt about 7 litres. I don't think this is bad. The motor is idling smoothly, very responsive and excellent on high revs. Thus far I am quite happy with the 165's.
Thanks AK ! Thanks Stephan, you may relax now fella !