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I finally installed Randy's straight skis on my Patrol a few weeks ago after collecting parts for months. Today the weather was kind enough to let me fly and make sure everything worked! Having never installed skis before, I thought it would be a good idea to document some of the lessons learned in hopes it might save someone else some time figuring everything out. I used this thread on Supercub.org as a reference which is very helpful, but there are several Bearhawk specific nuances.
I used the gear leg attach points because it's a tried and true method and I don't have any attach points for the rear check cable on my fuselage. The disadvantage to using these attach points is that you are going to have to remove most of the gear fairing. If you are doing a new build it would be a good idea to figure out a way configure attach points that won't interfere with the gear fairing. Also note that AC 43.13-2B 504.d (page 43) specifies that at minimum the lower 4" of a fabric covered gear leg should be exposed to allow for inspection of the axle attachment area when operating on skis. Something to think about considering all the extra stress skis have on gear.
First step is rounding up the parts. This took a long time mainly because I was waiting on the Titanium tabs.
20220107_165243.jpg
Parts List:
22' of 5/32 cable
(12) - AN100C5 Thimbles for 5/32 cable.
(12) - Copper crimp sleeves for 5/32 cable (don't use aluminum its not as strong)
(4) - Ski Tabs- I got these titanium ones from Carbon Concepts
(4)- Gear Attach Fittings- Also titanium from Carbon Concepts
(8) AN4-17 bolts with washers and nuts to attached the tabs to the skis
(2)- Superioring Bungees Part No. 70124-CW - Purchased from Airframes in Anchorage
(4) - Bungee ends- I got these from Airglas but they were very $$$. I wish I had seen the hardware store ones at the Supercub.org site from above before I bought them. Oh well.
(4)- Cable Ties to help wrap the bungee around the bungee ends.
* You may need to get new longer gear bolts due to the additional thickness of the gear attach fittings
Note: pictured above are 1-5/8" washers that I didn't end up using, I will explain why below
First thing is you will need to do before you start is make sure you have Randy (or do it yourself) oversize the pedestal axle bushings on the inner side of the axle to accommodate the 1-5/8" axle sleeve. The ones he supplies with the pedestals are both 1-1/2". I had mine bored out slightly over 1-5/8" ID but it still wasn't enough because of the raised rosette weld on the torque plate flange sleeve. I had to grind off the paint on the sleeve and wheel sand the bushing to get it to fit which ended up taking up a bunch of time.
20210625_091456.jpg
20220114_123825.jpg
The next step is getting the skis on the axle. Because the ski pedestals are exactly 5" wide with the bushings, there isn't enough room on the axle for the torque plate and bolts so you will need to remove the brakes and torque plate completely. Even after doing this there is barely enough room to get the axle nut on, in fact we had to enlarge the axle nut hole slightly just to get the cotter pin in. I took everything off, capped the brake line and taped it to the gear leg. This is why you don't need 1-5/8" washers- because the bolts are gone.
After getting the skis on, the next step is to do the rigging. Having never done this before it took an entire day and was very tedious. I would recommend having a hoist and a digital level for this because it will make it a whole lot easier. I followed the Atlee Dodge ski rigging manual which was very helpful. I would read AC 43.13-2B just for a reference but the Atlee Dodge method is much better. We set the front check cable for -9 degrees and the rear at 1.5 degrees. We used a fish scale to set the preload on the front bungee to 80lbs as recommended by Airglas. AC 43.13-2B specifies a much lower value but Airglas says 80 is better, especially since the bungee will stretch over time. The preloaded bungee length was 22-3/4". After flying today, I noticed that the bungee had stretched considerably was not tight at flying attitude. If I were to build it again, I would shorten the bungee cable section by 2".
Cable Lengths:
Front Check- 52-1/4"
Rear Check- 40-1/8"
Bungee w/cable- 44-5/8 (I would shorten to 42-5/8" if doing it over)
20211230_202054.jpg
After you finally get the rigging done, the next step is to attached all the rigging to the skis and the aircraft. I won't go into much detail on this because it's fairly straightforward. However, one Bearhawk specific problem is the back of the gear fairing support is in the way of the rear gear attach fitting and cable. Maybe there is a better way, but I solved this problem by cutting off the back of the fairing support. Note that I had previously removed the lower gear leg fabric portion of the fairing when I went to 31" bushwheels, so if you haven't done that then you will have additional items to remove if you are going to rig them this way. I'm going to have to re-work the fairing this spring when I go back to wheels but I will deal with that when the time comes.
Also, this is a good time to inspect and replace your gear bolts. I just replaced mine in the spring and they were bent when I removed them. Make sure that when you get new bolts they are long enough to accommodate the additional thickness of the ski tabs
20220114_145332.jpg
20220114_183557.jpg
20220115_185313.jpg
Hope this helps someone. It was a considerable effort to get them rigged and installed but it was all worth it after that first flight!
20220129_144952.jpg
I used the gear leg attach points because it's a tried and true method and I don't have any attach points for the rear check cable on my fuselage. The disadvantage to using these attach points is that you are going to have to remove most of the gear fairing. If you are doing a new build it would be a good idea to figure out a way configure attach points that won't interfere with the gear fairing. Also note that AC 43.13-2B 504.d (page 43) specifies that at minimum the lower 4" of a fabric covered gear leg should be exposed to allow for inspection of the axle attachment area when operating on skis. Something to think about considering all the extra stress skis have on gear.
First step is rounding up the parts. This took a long time mainly because I was waiting on the Titanium tabs.
20220107_165243.jpg
Parts List:
22' of 5/32 cable
(12) - AN100C5 Thimbles for 5/32 cable.
(12) - Copper crimp sleeves for 5/32 cable (don't use aluminum its not as strong)
(4) - Ski Tabs- I got these titanium ones from Carbon Concepts
(4)- Gear Attach Fittings- Also titanium from Carbon Concepts
(8) AN4-17 bolts with washers and nuts to attached the tabs to the skis
(2)- Superioring Bungees Part No. 70124-CW - Purchased from Airframes in Anchorage
(4) - Bungee ends- I got these from Airglas but they were very $$$. I wish I had seen the hardware store ones at the Supercub.org site from above before I bought them. Oh well.
(4)- Cable Ties to help wrap the bungee around the bungee ends.
* You may need to get new longer gear bolts due to the additional thickness of the gear attach fittings
Note: pictured above are 1-5/8" washers that I didn't end up using, I will explain why below
First thing is you will need to do before you start is make sure you have Randy (or do it yourself) oversize the pedestal axle bushings on the inner side of the axle to accommodate the 1-5/8" axle sleeve. The ones he supplies with the pedestals are both 1-1/2". I had mine bored out slightly over 1-5/8" ID but it still wasn't enough because of the raised rosette weld on the torque plate flange sleeve. I had to grind off the paint on the sleeve and wheel sand the bushing to get it to fit which ended up taking up a bunch of time.
20210625_091456.jpg
20220114_123825.jpg
The next step is getting the skis on the axle. Because the ski pedestals are exactly 5" wide with the bushings, there isn't enough room on the axle for the torque plate and bolts so you will need to remove the brakes and torque plate completely. Even after doing this there is barely enough room to get the axle nut on, in fact we had to enlarge the axle nut hole slightly just to get the cotter pin in. I took everything off, capped the brake line and taped it to the gear leg. This is why you don't need 1-5/8" washers- because the bolts are gone.
After getting the skis on, the next step is to do the rigging. Having never done this before it took an entire day and was very tedious. I would recommend having a hoist and a digital level for this because it will make it a whole lot easier. I followed the Atlee Dodge ski rigging manual which was very helpful. I would read AC 43.13-2B just for a reference but the Atlee Dodge method is much better. We set the front check cable for -9 degrees and the rear at 1.5 degrees. We used a fish scale to set the preload on the front bungee to 80lbs as recommended by Airglas. AC 43.13-2B specifies a much lower value but Airglas says 80 is better, especially since the bungee will stretch over time. The preloaded bungee length was 22-3/4". After flying today, I noticed that the bungee had stretched considerably was not tight at flying attitude. If I were to build it again, I would shorten the bungee cable section by 2".
Cable Lengths:
Front Check- 52-1/4"
Rear Check- 40-1/8"
Bungee w/cable- 44-5/8 (I would shorten to 42-5/8" if doing it over)
20211230_202054.jpg
After you finally get the rigging done, the next step is to attached all the rigging to the skis and the aircraft. I won't go into much detail on this because it's fairly straightforward. However, one Bearhawk specific problem is the back of the gear fairing support is in the way of the rear gear attach fitting and cable. Maybe there is a better way, but I solved this problem by cutting off the back of the fairing support. Note that I had previously removed the lower gear leg fabric portion of the fairing when I went to 31" bushwheels, so if you haven't done that then you will have additional items to remove if you are going to rig them this way. I'm going to have to re-work the fairing this spring when I go back to wheels but I will deal with that when the time comes.
Also, this is a good time to inspect and replace your gear bolts. I just replaced mine in the spring and they were bent when I removed them. Make sure that when you get new bolts they are long enough to accommodate the additional thickness of the ski tabs
20220114_145332.jpg
20220114_183557.jpg
20220115_185313.jpg
Hope this helps someone. It was a considerable effort to get them rigged and installed but it was all worth it after that first flight!
20220129_144952.jpg
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