Quick Jack Option

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8359
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Quick Jack Option

Post by 8359 » Thu Jan 09, 2020 5:06 pm

Saw this video the other day, and I think it's a pretty good idea. Got me thinking I could CAD up the plate mounted to the axle pretty easy. I'm going to re-purpose a pitbull motorcycle stand as the jack part. The inner diameter of the tube is 0.860" so it can accept a 1/2" NPT pipe or the end of the pitbull stand.

The design will fit the 120/140/150/170, but certain year models will need the 1/4" holes drilled out to 5/16" and/or 3/8". (Grove Type 2 but with 1/4" holes).

If you are interested in a set, let me know. I'm by no means trying to turn this into a business, but I figured since I'm doing the leg work I'd offer it up to the forum, makes no difference to me if I order 5 sets or 10. A set of two will be $110 shipped. I'm not making any money off them, this is my cost. I'm having them machined out of 1018 steel. The plate is 1/8" thick and the tube is 3/16" thick. Estimated mass is 0.318 lbs.

Most people who have done something similar have been able to get away with just a logbook entry. This would be considered an owner produced part per the FAA.

Video of operation:
https://www.youtube.com/watch?v=0nnfRKqxTP4

Part:
5016-2 Jack Tube.PNG
5016-2 Jack Tube.PNG (229.69 KiB) Viewed 233 times
IMG_7413.jpg
IMG_7413.jpg (106.67 KiB) Viewed 233 times

8424
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Re: Quick Jack Option

Post by 8424 » Fri Jan 10, 2020 7:33 am

That's pretty slick!

May have to talk to the banker (wife) about this!

Steve H

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Re: Quick Jack Option

Post by 8359 » Tue Jan 14, 2020 5:08 pm

Having some fun with the CAD. Modeled up with the 850 tires currently on my bird..
C120-Stand-01.PNG
C120-Stand-01.PNG (414.17 KiB) Viewed 124 times
C120-Stand-02.PNG
C120-Stand-02.PNG (351.85 KiB) Viewed 124 times

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8233
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Re: Quick Jack Option

Post by 8233 » Wed Jan 15, 2020 7:27 pm

Looks like a great idea but would you need a 337 to bolt that onto the gear the way it's designed? Just wondering how hard it would be to get approved.
David Freeland - CFII
1972 Bellanca Super Viking and 1946 Cessna 120

8359
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Re: Quick Jack Option

Post by 8359 » Wed Jan 15, 2020 7:31 pm

A few other people online have welded up a similar bracket. They all installed with just a logbook entry, no 337 or approval. But at the end of the day, I think it would be up to your IA. My thought is you aren’t using different bolts or anything, basically like bolting up a plate washer.

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Re: Quick Jack Option

Post by 6643 » Wed Jan 15, 2020 8:39 pm

Any alteration of the landing gear is a major alteration. So it boils down to whether or not this is an alteration. Personally, I think I'd let it slide. Just make sure you use the same hardware, and get the hole pattern "perfect" and the diameter spot on. If you're using MS20004 bolts I'd use MS20002-C4 washers instead of chamfering the part and having the bolt bear directly on the part, as it does on the gear leg.

Oh, and you're going to need longer bolts.

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Re: Quick Jack Option

Post by 8359 » Thu Jan 16, 2020 12:36 am

Thanks for the insight John.

The bracket has already been sent out, I double and triple checked the bolt pattern prior to sending it out, and I spec'd it with a close fit hole. I've been using the MS20004-28 with 3 washers, so I think I may be able to get away with less washers and the bracket. Too late to ditch the countersink, but I understand your logic in using the C4 washer in counting is as not "major." I guess I can always throw a washer under the bolt head, but it would have has much surface contact with the plate then. Material properties on 1018 vs 4130 (washer) are pretty close, but I guess pretty close doesn't count in aerospace.

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Re: Quick Jack Option

Post by 6643 » Thu Jan 16, 2020 8:19 am

The MS20002-C4 washer is hardened more than an AN960 washer, and has the countersink. (MS20002-4 is the same thing without the countersink.) I'm concerned that if the bolt bears directly on the part the metal will not be hard enough and it will loose tension over time.

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