April 18, 2024, 08:12:53 PM

Author Topic: N7 Build book  (Read 4500 times)

Offline mdu6

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Re: N7 Build book
« Reply #15 on: March 16, 2014, 07:28:57 AM »
If I understand correctly your question -  especially this point
Quote
maintain measurement integrity between adjustments
.

There is no need to maintain (positional) integrity between the 2 steps.  They are done individually, with of course the last step (clutch) inheriting the hub 'true' position.  You have to consider that there are only 2 ways to mount the clutch (180d) so the purpose is to find the best 'combined' geometry of the hub & clutch.




Offline Roger

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Re: N7 Build book
« Reply #16 on: March 16, 2014, 12:44:22 PM »
If I understand correctly what you answered, all you do is clamp the motor so that it does not move, put the indicator on what ever you are measuring and rotate the crankshaft to make the measurement.  As long as the motor and the indicator don't shift during rotation you are golden. 

R.O.G.
ROG
Retired Old Guy

Offline mdu6

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Re: N7 Build book
« Reply #17 on: March 16, 2014, 05:51:35 PM »
This is more or less the process:

1- Remove the engine back cover
2- Mount the engine in the vise (I use a homemade holder that simply clamps on one of the engine lug)
3- Mount the fan/hub on the engine and while pushing the crankshaft forward you put the engine nut on the crank and just tighten a little bit so there is no play possible on the crank
4- Start tightening the 2 clamping bolts. (2 bolts at the same time)
5- Check the runout - indicate the inside of the hub (page 13)
6- You want to slowly tighten the clamping bolts and check the hub to remain true (little runout as possible)
7- If the hub does not remain 'true' - you can
      a) backoff the clamping and start back one bolt at a time
      b) turn the hub on the crankshaft (using a crankshaft locking tool)
      c) tap the hub using a soft hammer
      d) etc etc
8- Repeat steps 4-7 until satisfied with the result -  this can take 10 minutes or 2 hours
9- Once you have the result you want, snug the engine nut and put some loctite on the crankshaft/nut
10- Lay the engine so the crankshaft is upright (loctite will slip down)
11- Keep the engine like this for 2 hours while you take a beer to cool down  ;D
12- Mount the clutch on the hub
13- Indicate the clutch (on the N7 - the only option is to use the one-way bearing) and write down the runout
14- Remount the clutch 180d - indicate the runout and decide which side is the best one
15- On some helicopters, I have use a file to create just enough clearance on the clutch bolt holes to 'move' the clutch around and zero in the clutch
16- Remove one clutch bolt at a time to apply loctite and tighten completely


« Last Edit: March 16, 2014, 05:59:24 PM by mdu6 »

Offline Roger

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Re: N7 Build book
« Reply #18 on: March 16, 2014, 10:33:41 PM »
Mario, thank you very much for the step by step.  When I am ready to do the procedure you will be at my elbow guiding me.   :) :) :)

R.O.G.
ROG
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Offline mdu6

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Re: N7 Build book
« Reply #19 on: March 17, 2014, 07:19:54 PM »
I'm OK with the elbow,  might have issues with other parts  ;D

Offline Roger

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Re: N7 Build book
« Reply #20 on: March 17, 2014, 10:37:06 PM »
 :) :)
ROG
Retired Old Guy

Offline mdu6

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Re: N7 Build book
« Reply #21 on: August 28, 2016, 08:25:09 AM »
Sorry for the long delay ...

The runnout is relative to the crankshaft rotation (nothing linked to engine position per say) and we do it in two steps (fan first / then clutch) simply to have more ways to obtain a final 0 runnout clutch (or close to it).