Ski planes don't HAVE brakes, everyone knows that, wheel-ski planes do.....and though I do a lot, in fact most, of my ski landings on mountain slopes of12 to 20% grade, this happened at the Afton Wyo. hard surfaced runway Talk about letting your guard down! In the summer when on the 29 " Airstreaks I baby them, always landing on grass unless told not to, and in fact have been into Afton several times and always land in the area between the taxi way and runway. Just another fun part of flying Bushwheels. With the skis on, I am limited to a max tire size of 8:00's, these tires are cheap and wear like iron, so I have no qualms about getting on the binders while on pavement.

So, as I was on short final I decided to see if I had finally got all the air out of my newer/larger Grove brakes. Due to the ski installation I am forced to position the caliper in such a way as to make it almost impossible to bleed all the air out, the solution to this is simple, but one I didn't think of before my last install. All you do is bleed the brakes, already plumbed, (pumping up from the bottom with a pump oiler) BEFORE you bolt up the caliper, just hold it there in a position that'll make it easy for that last little bubble of air to get out, THEN bolt it in place. I'll do this next time, but really this had nothing to do with my problem.

I made a decision to get on the brakes pretty hard, though I had a few thousand feet of runway left, just to play around more then anything on my small cheap tires, and of course to make the back taxi to the cafe shorter. So...I reared back and gave a mighty push (compared to normal very gentle applications) and promptly veered to the right. I let up, and glanced down to make sure my big insulated boots were not snagging on the wrong pedals, which has never happened before but that was the first thing that popped into my mind. Everything looked good so I applied both brakes again, favoring the left to correct for the earlier veer.

Shortly afterward I said a bad word, and to my credit reached over and killed the "mags" (none on a 912S but old habits die hard). The good thing about the lightweight composite Kiev prop is it very quickly coggs down and comes to a full stop, so when I hit the frozen snowbank at maybe 4 mph, only 1 blade impacted and cracked. The snow showed the prop was stopped, so of course no crank issues especially as the Rotax has a slipper clutch anyway. The hub, due to the blade flexibility, wasn't overly stressed, so 1 new blade (300 bucks) and I'll be back in business. Thanks to Mark Heiner at the FBO, who also helped get it back on the runway, the plane is currently hangared until the next break in the weather and then I'll fly it out on the wood club that came with the kit, landing back at my place still with only one brake, but now I KNOW I have only have one brake, and besides the runway is a solid layer of glare ice (so slippery even the cat is staying off it, and so slick it's even hard to photogragh) due to a weird freeze frost cycle so no braking action is available anyway! I almost forgot: as of now no explanation has been found for the total (nearly) lack of brake fluid on one side, they worked fine before takeoff. This wasn't due to air in the lines it was total lack of brake on one side only.

Well shit....

Ya'd better go down and surrender all your certificates and sign up for remedial training now.

Gump

Bummer. I know that feeling, only I didn't reach for the mags. I was peeking over the dash, wondering if I was going to get beheaded by the barbed wire fence.

A common weak spot on 912 motors is the prop shaft bearing boss in the gear box. The way it is webbed into the housing lends to cracking the housing on sudden stops like a prop strike. (I've seen it happen twice, now. Once on a 80 hp 912UL after a prop strike to a snowbank, which did not damage the Warp-Drive prop.)

This is not a difficult thing to check, but it does require removing the gear box and dye-pen checking the aluminum housing. Especially where (in this drawing) screw and washer, parts #14 and 15, retain the bearing.

sucks on the prop. But ski planes do have brake available now! and they work pretty darn good too. Jeremy Davis has come up with a set that work well and are STCd for several planes.

Good to know that about the gearbox, but I didn't have a prop strike in the classic sense. Due to my quick thinking (but not quick enough to identify the problem, one brake working 100% and the other 0%, and to let up on that working right brake and stomp left rudder and give it full throttle) of hitting the mags, the prop was totally stopped when I went into the bank at walking speed. No damage to the cowl even. Though my swiss muffler pipe that connects the stock muffler to the swiss one impacted just enough to rotate the muffler a bit due the spring mounts give, it popped right back into place with a good shove after loosening the bolts a bit. But the prop was flexed backwards just enough to cause a crack on one side. Now, if I had been in a remote area..... I would have been very tempted to fly it out, maybe after I got hungry or cold enough. As it was, no reason to even consider it, a cell phone call 60 seconds after assessing the damage had a friend on the way from Inkom.

I did discover the next day after gathering up what was needed for the repair that a 70" three blade prop won't fit in a Toyota Yaris hatchback no way/no how (though I did get 39.8 MPG on the drive over). So, I grabbed the prop tip, braced the root on the ground with my foot, and and after repeated flexing it finally broke at the crack. Then it fit. It gave me additional faith in the prop all in all. And I did get 879 hrs out of it. Best of all I got a new addition for the prop wall, a mix of wind turbine and aircraft blades. That's it to the left of the spinner.

Dang, bummer Tom. I've got a few broken Kiev blades on my wall too. My moto/crank/prop shaft/gear box were inspected and all to spec. Amazing really. The slipper clutch and flexible blades really do the job!

Hey Tom: glad your ok with a not to expensive fix. Kudos for manning up and taking responsibility. You sure it wasn't a massive internal system failure? Dam it there I go again.

Cheers

I'm glad you weren't turning at the time of impact, but I would still recommend inspecting the gearbox before you fly it. The UL in my example said he was in process of killing the motor and could not be sure if it had quit turning or not when it hit.

One mans opinion.

Beyond that, I'm also glad no one was hurt.

Exciting moments in aviation...

I was landing at PANO in the venerable PA-22 on Friday, and decided to see if I could land and get stopped by the first taxiway. The snow on the runway had been plowed, but not for a day or two, and there was fresh snow on the surface. As soon as I applied brakes the plane felt like it was fishtailing...so off the brakes and taxi down the runway...

All's well that ends well...

Glad it's working out for you with minimal pain. I'd take the man's advise on getting the gearbox checked, as well. Having that grenade in flight would be somewhat more expensive, methinks.....

And, Mark Heiner is a great guy to have around when you need a hand. Say hi to him next time you see him.

MTV

I got a ride over to Afton today from a fellow S-7 pilot, though for some reason he expected me to sit in back (the S-7's PIC sits up front), and I commented that in all the hours in S-7's I've flown I have never rode in the back! It was interesting to get the passenger POV, and kind of nice to just gawk at the scenary and not have to be concerned about the low ceilings coming at us: not my problem, PIC Joel can work it out, I'm just along for the ride

After breakfast at the cafe across the road, and the flight back (and a half dozen landings in the sticky snow, too warm) I finally got it back in the hangar and quickly found the cause of the brake malfunction. I recently changed (while upsizing my brake system and doing some other work) from 1/4" nylaflow tubing to 1/8", and in so doing left some of the 1/4" in place and simply routed the 1/8" through the larger size, using the 1/4" as conduit in effect. Now the funny part: the 1/8" somehow wore right where it entered the 1/4", just enough to cause the loss of pressure and total lack of braking on the left side. You would think this couldn't happen, (no apparent movement at this point) but it did, and in just 3 months. So, when I get the new tubing, I'll forgo routing it through the old stuff, and just chaff proof it in the usual fashion.

So, setting aside the cost of having a friend initially drive over from Poky to pick me up at Afton, the drive back home, the next day drive over with the spare prop (and a nightmarish blizzard drive back in whiteout conditions with 65 mph winds, first gear most of the way the viz was so bad) and then the flight over and back for Joel, the 45 mile drive this AM from my place to Joel's (he doesn't have skis so no landing at my place) and the replacement prop blade, with shipping, setting aside all of that, the total cost of the fix will be: 6' of 1/8" tube @ 15 cents per foot with shipping= about 6 bucks. Who says flying is expensive?

Alls well that ends well.. My first thoughts were ice in the system, but sounds like ya got er figured out. Glad it wasn't too bad.. Good quick thinking on your part tho..

That brake line tubing can have a pretty hard and sharp edge at the ends. I used 3/16 ID polyurathane fuel line (the blue Bing stuff) over my 1/8th inch brake lines for chaffe protection.