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"What I did on my summer vacation", or "I learned this from that"

gdafoe

FRIEND
Castle Well Airpark SE of Wickenburg AZ
Well, it wasn’t really a vacation; I’m retired, so I don’t get vacations anymore. ;-) I’m finally catching up with myself enough to sit down and put my experience last summer in writing with the hope that it might help someone else.

For several years around the end of May my wife and I head from home in Arizona to Nampa Idaho for about four months. We take our 5[SUP]th[/SUP] wheel camper and park it at a little RV park at MAF’s headquarters next to the Nampa airport. There we volunteer, working in the office and hangar on projects to help the worldwide work of Mission Aviation Fellowship. Well, I’m sure you all here can understand that spending four months at the gateway to the Idaho backcountry without my Super Cub would be a very unwise decision. So I catch a SouthWest 737 back to AZ and fly the cub up and keep it at KMAN for the months we are there.

I finished my Smith Cub/Turbine/Backcountry Cub and first flew it in February of 2009. I have just under 500 hours on it. One of the little niggling issues since early on has been that the right brake has occasionally been spongy. When I built the airplane I tried to set the brakes up so that there was no place for air to be trapped in the system making the brake hard to bleed. For the first year probably, I bled the right brake a few times to try to solve the sponginess that would show up once in a while. Of course to add to the difficulty the softness on the right side would disappear when I would start working on it. So over the years when this occurred I would try to find the cause but as soon as I tinkered with it the brake was normal I couldn’t make it go soft. I got in the habit of pumping the brakes on final all the time to make sure that it was not soft for the landing. Last winter when I was doing other work on the airplane I considered sending that master cylinder back to Dakota Cubs to have them figure out what was going on. However, I thought when they get it, it probably would not go soft so that won’t help anything. I didn’t send it in. I should have.

At MAF we do a Teen Aviation Camp every July at the Cascade ID airport for a week with about 12 teenagers. For several years we have used three airplane including my Cub to give the teens some experience. It is a great week flying with the students giving them a taste of aviation. We do some ground school each day and then fly with each one for about 30 to 45 minutes every morning. Then in the afternoon we go Whitewater rafting, Ride the Zip line, or float down the Payette River that runs just behind the airport there.

The second morning of camp I was flying with a young man and returning to Cascade I landing on runway 12 and did a very nice smooth, slow, short landing (really!), rolled out a bit then applied a little bit of braking. The right brake pedal went clear to the floor. The braking on the left started a swing to the left. I said, “OH OH here we go”. We went for a ride to the left. Now as some of you have experienced, you might be going very slowly, but the ground loop doesn’t seem all that slow. About one quarter of the way around the right AOSS strut buckled and broke, allowing the gear to fold and drop the right tip wing on the ground. After a few feet of dragging the tip the wing folded. We came to rest at about the 180 degree point and quickly exited the airplane which was just off the runway.

It is a very helpless feeling to have absolutely no brake on one side when you need just a tad of braking to help with directional control. I was so slow that the rudder had little on no effectiveness remaining so around we went. Yes, I have thought lots of times about what I could have done differently. Added a burst of power, or tried to fly away from it and come back around, etc. Everything I have thought of as a possibility could have easily made things much worse. I did not get the prop so no engine damage, just damage to the right gear and right wing.

Later after we took the Cub apart and got it on a trailer and back to the hangar in Nampa, I took the right master cylinder out a disassembled it to see what might be the problem. I found a significant amount of metal shavings in the master cylinder and a little tiny cut or notch cut out of one of the O-rings. It was very small and a bit to the side of the O ring. The O-ring grove is wider than the O-ring allowing the O-ring to roll just a bit in the grove. I suspect that all this time when the brakes where occasionally soft that O-ring would roll just a small amount and allow that notch to leak some fluid past it. On this occasion when I had no brake at all maybe the notch had gotten a bit bigger or the O-ring rolled just a bit differently allowing a bigger leak resulting in no brake at all. All that is some guessing. I’ll never know what really happened. I have wondered if I actually pumped the brakes on final, as was my habit. I don’t know. I expect I did as I “always” did, but of coarse I might not have that time. As some have experienced the clean up after these events are not the most pleasant and quite expensive.

So the result now is that I have a perfect Smith Cub left wing for sale, and two new BackCountry Cubs latest version of their wings with 4 inch deeper flaps and ailerons installed on the Cub. They have the much lower hinge line on the flaps, which results in a lot more effective flaps. They have different geometry on the controls for both flaps and ailerons. The roll rate is great and the stick forces are nice and light. It gets off really short compared to the standard Smith Cub wings which perform really well themselves. With this set up I notice some less elevator effectiveness at very very slow landing speeds. Bruce tells me on the current kits they enlarge the elevator a bit to compensate for this.

So what did I learn and what do I wish I had done differently? Don’t put up with something that is not quite right on the airplane. It never came to mind that whatever “little thing” that was causing the problem might just result in complete brake failure on that side. Pursuing the issue to resolution will in the end be the only thing to do. Something like this really bites hard when it fails. It is expensive, it is humiliating, and it is a lot of work. For 48 years I have been privileged to fly in some of the most interesting places and to land at some of the most challenging airstrips in the world. I have dreaded the day I might bend an airplane or hurt someone. By the grace of God I had not bent one until this incident. Even now I am so very thankful that no one was hurt and my student and I both learned from what happened. As our friend Bill Rusk says I have been “very blessed” and am thankful for it.
 
That's quite a story Gerald. I'm sure writing and posting it wasn't that easy. But it helps others when they make a mistake to know that a very experienced pilot can have ground handling issues too. I use brakes on almost every landing at touchdown and losing one would make for an unpleasant ride.

I'm curious, it sounds like you didn't have safety cables with the AOSS system. Do you think that would have saved your wing?

Glad there were no injuries and your plane is back together.
 
I guess I was not clear on how the strut buckled. The force on the right gear buckled the AOSS, it broke just inside of the sleeve right next to the canister. The right gear folded inward not outward so the cables didn't help.
 
If your gear is tracking straight, you should rarely need a brake during landing?
 
Gerald

Thank you for that post. Great words of wisdom. I have some "little" problems I think I will tackle now.

Bill
 
Great post, Gerald. I had a very early set of the Dakota masters and had one that cut o-rings quite a bit. I can't remember if they replaced the whole megillah or just some parts, but they have worked without a hitch since. I lost the right brake when on amphibs on land, and did a lot of 270's to get home since that is the ONLY way you can steer an amphib.

sj
 
50% of my landings are lazy on the brakes because the Lake Hood runway exit is near 1000' down field. It takes power to get there. 50% of my landings are hard on the brakes because I always try to stop even with my weekend tie-down and that's 400' from the normal approach threshold and that strip is only about 15-16' wide. Last year while taxiing out at Lake Hood strip my left master blew and nearly had my prop chew up a neighbor's 180 when it veered off the taxiway. Lucky timing that it happened there and not at my narrow strip where I'd have been about 20 seconds later in my brakes' life. Upon rebuild it was difficult to get the feel equalized between the two pedals so after a few hours of adjusting the newly rebuilt side we finally rebuilt the opposite side. Disassembly of that supposedly healthy master was educational. 20+ years of sediment and gunk lined the assembly. Clearly both masters had been overdue for overhaul and that I had escaped bending the airplane was pure luck. I tell that story to my other Cessna friends to plant the seed that if they use their brakes they need to know what's inside their brakes. The harder they use them the more important it is.

Thanks for the comments about the BCSC wings. Very interesting.
 
Hey Gerald, we met at MAF August-September 2014. I sent you a PM. I was hoping I would bump into you on this site. :) Sorry to hear about your misfortune.
 
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How short? ;-)

Glenn

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About this short
 
I lost my left brake on my experimental a few weeks ago, no drama, just a gradual loss of effectiveness first noted whiled taxing. I have yet to determine why, (intact lines, fluid on the tire, pretty sure I know where to look!) but will of course find out when I take the Airstreaks off and switch to my 8:00's prior to mounting the retract skis. I'll be darned if I was going to tear into it and then put it back together just for a couple weeks only to tear into it again for the ski install. I also wasn't going to miss the last few days of Airstreak flying. I've flown several times since then, even making new site off airport landings. I figure I fly all winter with NO brakes while on the skis, so what's the big deal? Good practice for ski flying in other words, it really makes you think. This has included x wind landings on my 18' x 400' mountain strip, that's what the rudder is for. Unexpected and total loss of one brake is a whole different matter! Knowing I have one brake out not so much.
 
This is why you have brakes.......


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Dennis Wittenberg (DW) having fun. Full stop landing.


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Getting ready for T.O. I don't know for sure but I'm thinking it might have taken a little shot of Nitrous to make it off.


Bill
 
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