Tips, & Opinions of using/installing Federal 2500 straight skis

[DaCub-DaCub]

I located a beautiful set of straight federal 2500's with new UHMW bottoms. These were born in 1951 and look to be in their first year of service!
Having the high pedistals I plan to run them on std length gear of 11/4" Does any one have a 337 they wish to share??

These skis are huge and look to be sufficent to install on my 180. I arrived at this point following an experience with an old set of Wesco's that I promptly sold after a Brooks Range landing that left me in snow to the air intake. I tried the Landis wheel penetrations for a period, and while a great ski for dual needs they are somewhat of a compromise. With these Fed 2500's I may have gone to the opposite extreme as the Wesco's
Any sharred experiences would be great.

 

[mvivion]

Those are big skis, and they are HEAVY skis, for the size of a cub. Great skis, though. I'd consider selling them and buy a set of Aero 3000s, or see if you can work a trade. Much lighter, and good skis as well. But, these will hold up like the tanks they are, so if you install, they'll work well for you. The taller pedestals are a distinct advantage, for sure.

My preference is to attach the forward cables to the firewall at the engine mount attachments, as opposed to attaching them to the gear fitting. I like that pull angle much better, and I think it's a safer bet.

MTV

 

[stoddard]

Keep in mind the Federal 2500 are taller and the long prop would still be legal. The Aero 3000 the long prop is not legal unless on extended gear.

 

[DaCub-DaCub]

Thanks I appreciate the heads upon the prop clearance, (from Bill I assume). I don't own anything but two 82-41's and sold the 3" extended gear with the w/penetration skis, n' traded an old set of 6" Hendricks gear to a buddy for a Cleveland setup still in the box.
Mike, thanks for the tips on the Fwd. cable mount I like that idea! Do you place the tabs behind the swing mount bracket or at the bottom of the swing pivot bolt? Suppose I can pick-em up from AD or Stoddards too??
These skis are so beautiful, If I don't us'em I will wall hang them next to my european 70" 7x7 brow-tine mount and hope we don't get another Good Friday shaker again.
This is both the most beautiful time of year and the saddest when the Eddo's come off! I figured I would get a jump on the ski install requirements

 

[skywagon8a]

My preference is to attach the forward cables to the firewall at the engine mount attachments, as opposed to attaching them to the gear fitting. I like that pull angle much better, and I think it's a safer bet.
MTV

Attach the rear cables to the float fittings for the same reason.

 

[nanook]

Bringing this to life to see if anyone has the actual weight of the Fed. 2500A.....

 

[907cub]

I doubt there much, if any heaver than my old timer Landies fiberglass with uhmw bottoms bolted on.

 

[NunavutPA-12]

I looked at the Aero 3000 skis on High Country Aviation's web-site. If the price list is current, they seem very reasonably priced. Maybe I can afford skis after all, now that I've decided that retractables are out of my price range.

My Experimental PA-12 (160) has an 82-44 Borer (which I'd like to re-pitch to 42-inches), and I have a set of standard gear.

So I would need extended gear, I guess (three inch or six inch?), and the rigging kit.

My 'plane has always been on floats, but with just a three-month season I really need to get some skis.

It looks like, for about $6,000 I can get the Aero 3000's, extended gear, a Reiff heating system and a good set of covers!

I'd appreciate any advice I can get!

 

[tamarack]

Someone mentioned the legality of installing skis on standard gear with a long prop...
There are several STC's for the long props and they have differing axle heights, one of which allows the long prop on standard gear and several ski combinations. No, I don't recall which STC right now, but I will look when I get to the hangar.

Good thread.

Vickie

 

[skywagon8a]

Part 3 applies to Cubs, 23.925 is essentially the same. As long as the prop meets the following clearances it should be in compliance unless there has been some special condition applied. Even though axle heights are mentioned in the STCs it is the prop tip clearance that is of concern.

Sec. 23.925

Propeller clearance.

[Unless smaller clearances are substantiated, propeller clearances with the airplane at maximum weight, with the most adverse center of gravity, and with the propeller in the most adverse pitch position, may not be less than the following:]
(a) Ground clearance. There must be a clearance of at least seven inches (for each airplane with nose wheel landing gear) or nine inches (for each airplane with tail wheel landing gear) between each propeller and the ground with the landing gear statically deflected and in the level, normal takeoff, or taxing attitude, whichever is most critical. In addition, for each airplane with conventional landing gear struts using fluid or mechanical means for absorbing landing shocks, there must be positive clearance between the propeller and the ground in the level takeoff attitude with the critical tire completely deflated and the corresponding landing gear strut bottomed. Positive clearance for airplanes using leaf spring struts is shown with a deflection corresponding to 1.5g.
(b) Aft-mounted propellers. In addition to the clearances specified in paragraph (a) of this section, an airplane with an aft mounted propeller must be designed such that the propeller will not contact the runway surface when the airplane is in the maximum pitch attitude attainable during normal takeoffs and landings.
(c) Water clearance. There must be a clearance of at least 18 inches between each propeller and the water, unless compliance with Sec. 23.239 can be shown with a lesser clearance.
(d) Structural clearance. There must be--
(1) At least one inch radial clearance between the blade tips and the airplane structure, plus any additional radial clearance necessary to prevent harmful vibration;
(2) At least one-half inch longitudinal clearance between the propeller blades or cuffs and stationary parts of the airplane; and
(3) Positive clearance between other rotating parts of the propeller or spinner and stationary parts of the airplane.

 

[PA14driver]

Bringing this to life to see if anyone has the actual weight of the Fed. 2500A.....

Federal 2500A skis weigh 32.4 lbs each and the Aero M3000H skis weigh 29 lbs each. The Federals are 70" long by 14" wide and the Aero's are 72" long by 16" wide.

 

[aktango58]

A couple of notes: just because your paperwork says it is 72x42, and it is on the prop, it might not be...

Point is, measure the prop clearance before you get bent out of shape on gear length, often the propellor tips have been 'field' modified and cut down at the shop. Your milage may vary, but I have two propellors of the same lenght/pitch that do not measure the same.

Back to ski discussion: I have a set of the Aero R2800 retracts. I have had them installed on three aircraft now. Each time I have had to talk to Aero and get parts, help and ideas. Aero Ski folks have rivaled Bushwheels for best customer service in the industry, so I can not say enough good about them.

I needed the retract for my use, They work great. Maybe I could do better on strait skis, but when flying a 90 hp champ I took off in knee deep wet snow, (tracked it a few times) in about 1500 feet. I flew that thing out of places that even with strait skis felt small.

Go to Canadian tire and get one of the ceramic heaters, or two, and use them in your cowl and cabin for pre-heat. If you need the retracts, try out the Aero set, they are light and much less expensive than the other options.

3" gear is all you want to go. 6" you will probably break the brackets off the longerons.

We all talk about performance, but a cub, or 12, (which I had the r2800's on for a while) is a great ship for skis, especially if you are not in wet snow all the time. I often left the wheels down because in soft snow it made little difference. Only on the wet and crust was it really critical.

I know you all think I am crazy, but I was also not trying to always go into short areas, and after a 180, a cub on retract is a rocket ship.

 

[nanook]

Thanks PA14driver, is that bare bones wt? Or finished with rigging and Ptex?
NunavutPA-12, you have to tack on the shipping cost to their prices. Drop shipped from The factory in MN. They Quoted me a cost of @$390 US to Fairbanks....

 

[Crash]

I've run a set like these for years. They really work!

http://www.supercub.org/ppc/showproduct.php?product=2765

Crash

 

[tamarack]

While prop clearance is a concern, I do not see a regulation violation with signing off a 337 for installation of skis on standard gear as long as the ski axle height meets the STC.

Vickie

 

[sierra bravo]

Compatibility of multiple STCs is the responsibility of the mechanic. How does a Borer prop figure into that? I've not seen a ski STC name a Borer as part of the ski installation. Mechanics I know require extended gear for most Cub ski installations on planes with Borers. I've never done the measurements for prop clearance. Don't care. Extended gear is basic equipment in my mind.

http://rgl.faa.gov/regulatory_and_g...a17c099806a3e38f85256687006f1418!OpenDocument

 

[skywagon8a]

While prop clearance is a concern, I do not see a regulation violation with signing off a 337 for installation of skis on standard gear as long as the ski axle height meets the STC.

Vickie

Compatibility of multiple STCs is the responsibility of the mechanic. How does a Borer prop figure into that? I've not seen a ski STC name a Borer as part of the ski installation. Mechanics I know require extended gear for most Cub ski installations on planes with Borers. I've never done the measurements for prop clearance. Don't care. Extended gear is basic equipment in my mind.

http://rgl.faa.gov/regulatory_and_g...a17c099806a3e38f85256687006f1418!OpenDocument

The prop clearance regulation is the reason that the FAA placed an axle height on the prop STC. The Borer STC was issued before it became popular to install extended gear on the Cubs. So, originally the FAA was "suggesting" that perhaps there should be some larger tires installed before the long prop was installed. If you think about it, you would be legal, with a deviation, to install a long prop with a low axle height "if" you had already installed longer landing gear since the extended gear would raise the crankshaft height enough so that the prop clearance was correct.

My point in posting the prop clearance regulation was to help the non mechanics here understand the why of the axle height limitation. All A&Ps know that that the prop clearance regulation exists and that it is part of their thought process when combining various STCs.

Can anyone say how much the Zero thrustline STC raises the prop clearance? Is it enough to provide the "Borer" clearance/axle height requirement? Maybe?

 

[sierra bravo]

I don't know of the "axle height" your refer to. My Borer approval didn't specify an axle height. And extended gear wouldn't have different axle height. And Big tires aren't really a solution since the requirements include deflated tires. I had a nose dragger that I needed a field approval for to fly a seaplane prop. That was a process. Flat tire, flat nose strut, etc. It had to be demonstrated.

 

[skywagon8a]

As you say some prop STCs do not mention axle height. I have seen them both with and without that notation. You are correct about the approval process. Since I was not involved in the process for the above mentioned STCs I can not comment further on what the FAA engineer's concerns were. The extended gear would increase the prop clearance enough so that the axle height was not an issue.