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locktight on propeller bolts?


digidydawg
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Brand new Nirvana Rodeo with 3 bladed prop. Ran 5 liters of gas through it in driveway just checking things out and breaking it in a little bit. Afterwards I was shocked to find every single propeller bolt loose and 3 were visibly backed out at least 1 cm. Obviously I cranked them down on assembly. I'm fairly new to the sport and find it very disconcerting to think what might have happened if I had been in the air and one of those blades cut loose.

Please tell me this is just a break in thing and I don't have to worry about bolts coming loose with just a half a tank of gas of use. Again I cranked them down pretty tight, can't imagine any tighter before starting to strip things. I transport my machine in a trailer so don't have to disassemble it after every use. Would you recommend using locktight on the bolts? Any other suggestions besides the obvious(tightening them down harder)??

thanks:)

dd

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Make sure you're using Nylock nuts, not plain ones... and if you are using Nylock nuts then remember to cycle them... Once they've been loosened a few times, they loose their bite, and need to be replaced. Generally mine get changed after 3 or 4 cycles.

Also the sequence of tightening the prop bolts is important... you shouldn't just go clockwise or anticlockwise around the bolt array.. but do opposite pairs in sync.

Regards,

GD

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The 3 blades interlock to effectively form a single hub, so it is still important to tighten in opposite pairs. Also it is important to use the correct torque or you can induce vibration which can loosen nuts. The manual should specify but 12-15Nm is about right for M6 bolts and 20-25Nm for M8 bolts (for a carbon prop).

Helix suggest wire locking for bolts or Locktite 372. Assume you bolted through the front alloy pressure plate, and not directly through blades ?

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This hapened to me once on my first machine. ( a fly castellucio)

I went for a fly (45mins) and when i landed my prop bolts were half undone, all of them. I had definatley just checked them before take off they were tight.

I noticed that they had no washers on them but were bolted straight to the metel round cover plate. I simply added washers to them then never had a problem.

This was one of my first flights on it and my first machine, and it came like it.

This was on a wooden prop, think i had a lucky escape another ten mins up there and who knows.

Make sure you have washers on !!

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This is what I did to my Friday Parajet bolts after they decided to loosen up after only being run in the back garden for 8 minutes.

These bolts are already supplied with spring/lock washers and they were all tightened only a couple of days before this test run.

I cannot believe that of all the motors I have looked at do not really seem to have much lockwiring on them? Especially on such vital fixing points.

It just seems to be the exhaust retaining springs and thats it!

I appreciate its not the 100% standard way of lockwiring multiple bolts, but it does the job.

P1010048-1.jpg

P1010050.jpg

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wow, that looks like it should do the trick. Did you drill those bolts yourself? They didn't come like that did they?? I can see how you started the thread but how did you finish ... what kind of knot did you use??

No, the bolts did not come like that. Just a brand new drill bit and steady drilling in the vice, holes deburred afterwards with a countersink bit.

The ends of the lockwire are twisted for about 3-5 turns then just tucked into the socket of the bolt head. Its the one sitting at about 3 o'clock in the pics.

Si, page 8 of my owners manual states in step 4 "Finally tighten each bolt with equal torque HAND TIGHT ONLY (be careful not to over tighten and crush the carbon fibre propeller hubs).

Now maybe I'm being a bit thick here, but could someone explain the principle of obtaining the 'equal torque' setting - by hand?!

Do you wait until the cracking of carbon fibre strands is heard, or add 1/8th further turns after this lovely crackling noise?

For a rotating part that is crucial to the safety of all concerned on a 'flying machine', do you consider the instructions adeqate?

Yes, I did tighten the bolts until the spring washers were laying flat under the heads of the bolt.

The numerous 'issues' I had with this, a £4000 new machine, I would rather not hijack this thread with. But suffice to say, it has not even been flown yet.......

Not having a dig at you personally Si, but needless to say, Parajet would probably not be on my next 'buy new' machine. :wink:

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I know where your coming from Enzo200500

over the years I too have had major problems with things falling off NEW paramotors :shock:

manufacturers I am sure just don’t care about our lives....I’ve had exhausts, airfilters,and a gearbox, fall off in flight It’s because of these experiences I now festoon my paramotor in lock wire and guess what :wink: nothing now falls off .... :idea::)

ps nothing will fall off this wonderful machine that I’ve seen for sale sounds like a bit of a bargain to me :D

ads_item.php?id=367

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Hi,

I have to second nylock nuts:

ss_nylock-nuts.jpg

150 Hours on my miniplane so far and never had one propeller nut go loose.

I like the wired DIY bolts, but I guess that is working only when the bolts go straight to hard metal. If they have nuts on the opposite side like many propellers do, then we are back to square one since a chain is only as strong as its weakest point.

I don't like to put semi-permanent locktight or similar products because you need to adjust prop balancing once in a while by micro-tightening the bolts on the unbalanced side.

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Hi,

I have to second nylock nuts:

ss_nylock-nuts.jpg

150 Hours on my miniplane so far and never had one propeller nut go loose.

I like the wired DIY bolts, but I guess that is working only when the bolts go straight to hard metal. If they have nuts on the opposite side like many propellers do, then we are back to square one since a chain is only as strong as its weakest point.

I don't like to put semi-permanent locktight or similar products because you need to adjust prop balancing once in a while by micro-tightening the bolts on the unbalanced side.

I think you mean tracking NOT balancing??

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Hi,

I have to second nylock nuts:

ss_nylock-nuts.jpg

150 Hours on my miniplane so far and never had one propeller nut go loose.

I like the wired DIY bolts, but I guess that is working only when the bolts go straight to hard metal. If they have nuts on the opposite side like many propellers do, then we are back to square one since a chain is only as strong as its weakest point.

I don't like to put semi-permanent locktight or similar products because you need to adjust prop balancing once in a while by micro-tightening the bolts on the unbalanced side.

I think you mean tracking NOT balancing??

Yes of course, my mystake ;) We use the same word in italian but I actually meant tracking, thanks for pointing it out.

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None nut type prop securing.

Some machines like the Fresh Breeze Sportix use Stainless bolts into a hub. They come with flat anti loosen type washers with machined pattern on them. The bolts are tightened to 12nm as recommended in the manual.

I have had no problems. I have used weaker 222 type locktite in the past but dont bother with it now.

On my H&E it uses Bolts with nylock nuts and spring washers and again I used to use the 222 locktite but not anymore.

The subject of blade tracking is interesting. Not many UK pilots bother other Europeans like the Belgian PAP team use a semi soft spacer behind the prop which can be squashed down and tracking adjusted. Guess it also acts like a spring washer maintaining pressure.

Not sure if tracking is the correct term as using solid form blades like wooden or even 2 or 3 section blades the tracking is set at manufacture and cant be changed. What you are altering is the thrust line. Thats if tracking is refering to the blades following each other along the same line or track.

Track and balance on helicopters is vital as the blades are all mounted seperately, when they drift out of alignement (not abnormal) vibration occurs.

Regards.

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