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Parajet pre flight checks


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Simon, as well as the security of the prop bolts. Is the tracking of a Parajet 3 blade prop an issue? Or this mainly more critical on larger diameter wooden props.

After checking a manual for PAP With Black Devil Engine fitted. I found that they stated the following

At the PAP workshop we tighten the screws to a pressure of 1 kg/m. You must check the propellers tracking once the screws have been tightened (Photo 13). The tracking is the movement observed when you turn the propeller and it is a consequence of an asymmetrical tightening of the screws. To check the tracking of the propeller:

- 1°: Take out the spark plug to facilitate easy engine turn over.

- 2°: Lean a long instrument (spanner or rod) against the chassis. Turn the propeller and check that the ends of the propeller pass by the spanner or rod at the same distance and on the same axis.

- 3°: If they do not pass by the instrument at the same distance or axis you will have to tighten the screws on the end that passes by with a greater distance.

IMPORTANT: Remember to re-tighten the propeller screws after the first hour of flight every time you replace or reinstall the propeller.

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Hi All,

As all you regulars on the hill know I dis-assemble and re-assemble my prop every time I go flying due to it having to fit in the car so possiably I have more experiance of this procedure than most.

I do my nuts up to what I would describe as firm hand pressure. Thats a firm pressure applied with a standard spanner ( or allan key ) by your hand only not your arm or body weight. It matches in well with Simon W description of hand tight then 1/4 to 1/2 turn extra. The important thing is to make it even across all the bolts by doing a bolt then the one diagonaly across from it repeated till all the bolt are done, the same as wheel nuts on a car or head bolts on a cilinder head, remember its not the bolts themselves that hold the prop on but the grip between the hub behind the prop and the plate in front of it. I've never used a torque wrench ( I go by feel ) so cant give a figure but if I had to take a rough guess it would be 10 to 12 psi. This is on an Adventure A3 with a standard wooden prop but I cant see it being much different on other machines. So far I have had no problems or issues using this method and to be honest I dont expect any.

Please dont horse them up as tight as you can as this will I am sure either damage the prop or stretch the bolts which will weaken them making them useless.

I hope this helps.

Cheers Col.........

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Hi Norman from Capetown. Had hoped to hook up with Keith Pickersgill's operation for a bit of paramotoring but unfortunately it's a bit too windy to fly down here.

I always use feel to do up my bolts but out of interest a while ago I checked what figure I had set using my torque wrench and it turned out to be about 10 lb/ft. It is interesting to note that exactly 125 Nm happens to be exactly 92 lb/ft so I wonder if someone had converted the figure and then left the decimal point out.

edit: oops, just noticed that Martin had already pointed out the relation between the Nm value and the lb/ft one.

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Hi Ian,

If you bump into Keith please give him my regards.

You might just have something there with the decimal point.

Enjoy the Cape and don't drink too much of that luscious red wine nor fork down ridiculous quantities of the fillet steak that you can put your finger through.... Hmmmm.

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Simon,

I quite envy you your SA trip. The food and wine are exquisite and so inexpensive (at least they were when I was last out there). It would be a terrific place to go for another future PM holiday, particularly given the level of support and the welcome that would get lavished on the lucky ones. The South Africans are a fine lot (a few odd ideas here and there but we won't hold that against them) and can teach us a thing or too about hospitality. And the country.... breathtaking!

Ian,

Eat the steak, :lol: Paramotor to your hearts content but wear your running shoes for that unexpected out-landing eh? Either that or pack the Ruger.

'Real Lecker scoff M'nier' :lol:

Ahhh, Franschhoek!

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HARTENBERG-PANORAMA-taken-b.jpg

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I had the choke thing happen to me once on my parajet but I put it down to not making sure it was clicked open. Now I build that check into my pre-flight after warm up and before strapping in. I couldnt swear it was my failure but it has not happened again.

I have had fantastic after sales from Giles with two ancillary units failing and being replaced by return of post.

I remind myself that these are experimental aircraft and very limited production runs and they use some parts from other manufacturers (carbs, starter motors etc). That they are as reliable as they are is testament to Parajet's attention to detail. I had a PAP before and it is also a very good unit but when I needed anything for it, it was always many days and sometimes a week or three to wait before I could fly it again.

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I think one of the many really strong selling points of the Parajet is the fact that it is so local with a lot of interest from the factory and this same issue is almost always a minor snag with the european manufacturers. I may well move accross as well when they get a cost effective Wankel on the line up as described in the latest Paramotormag.

I am curious about the choke thing though. I gather the Walbro WB37 is the carb normally used on the Parajet range. My BD also has a WB37 but it is the C version which does not have the choke. My pull start set up always starts second swing whether hot or cold. Bearing in mind the engines are so similar has anyone tried not using the choke at all on the Parajet? I would imagine it's human nature to assume you need to use it if it is fitted but I wonder if it is really necessary. If not, why not just remove it? The carb can easily be primed by pressurising the fuel system (either by primer bulb if fitted or by blow tube) and carefully depressing the metering diaphragm via the small hole in the top surface of the carb. Walbro's WG8 carb in its original form contains a small button to do just this but it is easy to make the same set up from scratch for a few pence from a rivet, a washer and a small spring. If anyone's interested I can forward on details showing how.

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I think i have solved the choke problem. I removed the air box and checked the aluminium plate. I noted that the countersunk recess that locks the choke open was worn by the ball bearing effectively making a "ramp" for the locking ball bearing to vibrate out and allow the plate to move. I have soken to Giles and he is sending me a new plate in the post , problem solved.

I have made a mod though as a fail safe device. I have screwed a small metal disc about the same size as a 2 pence piece (I used a dog tag because it had the hole already drilled in it) over the choke plate on the left hand side (left hand side sat in the harness facing forward), but left lose enough so that it can be spun. To close the choke now i simply spin the disc round to allow the plate to slide open. When i slide the choke to its operating position the disc drops down automatically and the plate cant move because it is covered by the disc. ( I have used a similar principal on agricultural eqipment but on a larger scale).

Perhaps this could replace the ball bearing and spring meachanism full stop? :?:

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