Bean Field

Bean Field

created July 23, 2015

After remaining at 1300' and a heading of 150 degrees while departing OSH Airventure 2015, I reached my "best speed" altitude of 7500', although I'd have crept up to my more usual 9500' eventually. Just before I got there I heard a quick little high pitched whine that made me wonder if it was an engine noise or a radio noise. I didn't think much about it, but it might have been the sound a bearing makes while "spinning". A minute or two later, the engine starting loosing RPM, and despite messing around with the mixture, and backup ignition/fuel pump power, in about 20 seconds, the engine was completely dead. Attempts to restart revealed that the prop was not going to rotate past a certain point, so something internal to the engine was interfering with rotation. I punched the "nearest airport" function on the iFly 720, and there was only one airport within gliding range. I knew that I'd only have about a 12 mile glide range from 7500', and this is the only one I could make. I keep the "range ring" function on all the time, so there are circles 5, 10, and 20 miles in diameter displayed on the screen of both iEFIS and iFLY 720 at all times, depending on altitude. The iEFIS also shows a range ring that is dependent on current glide rate, so it rubber bands depending on altitude.

As you get closer to the ground, this ring shrinks into nothing. That's what I was facing toward the end of the glide, shown above. The wind was out of the west, so I was planning an approach from the east. As you can see, I was approaching from the south into 2T5 (east of West Bend, WI), a 2900' turf strip, but simply couldn't identify anything that looked like a runway, so after all my altitude was burned up, I turned right (downwind) to land in another field in the last few seconds. I later found out that the airport had been sold the previous year, and most of the runway was planted in corn now, with a very short remaining portion devoted to RC model flying! Most of the brown soil you see in this winter-time photo was 8' tall corn when I flew over...not the best thing to land in.

Here's what the airport looked like in 2012, according to That looks a little more inviting, but it was simply not there. Looks like I need to amend the sectional!

I was "on the fence" between the road and the bean field I was over, which was punctuated by a corn field. I knew if I didn't get stopped, the corn field would stop me pretty quickly. An approaching 18 wheeler clinched the decision to choose the bean field, and the touchdown point was pretty close to where the blue line ends. The end of the extended red line is where the plane ended up, about 15' into the corn. The plane was amazingly intact, and I don't even think any paint was traded with the corn. Other than a broken prop and a wheel pant fracture, the only damage was to the tailwheel area, after the tail pitched up and then dropped after the corn impact. The tailspring itself was still fine, which surprised me.

A local news helicopter showed up and took this picture for the newspaper.

Here's a photo that Larry Howell took while I was talking to the FAA investigators who were writing up the report. I deliberately put the plane as close to the road as possible to make it easy to remove the airplane. I can't possibly thank Larry enough for his efforts on this. He dropped what he was doing at OSH, went shopping for everything we could possibly need to pack the plane in a U-Haul, and then appeared (as usual) to do whatever he could to help...and boy did he help!

Besides the usual paperwork inspection, I also explained how I got here and wrote up a statement. The investigators walked the tracks on the ground, and remarked that it was clear that the brakes were working fine! Given the minor damage, it was labelled an incident, rather than an accident.

The thing I want to point out here is the amazing packaging job we did to get the airplane into a "fifteen foot" U-Haul truck. The 15' truck was the longest available locally, but when we picked it up it was clear that about 2.5' of that length was over the cab of the truck, so we really only have about 12.5' to work with. I was ready to kill more daylight looking for a longer truck, but Larry has moved many planes over the years, and suggested leaving the door open and immobilizing the plane. This guy's middle name is "Confidence".

Another brilliant idea of Larry's was to make simple slings for the wings from the packing blankets, which completely protected the wings from damage. We used two U-Haul blankets, wrapping and stapling each end around 1x2 boards, and then screwing the sling to the tie-down slats in the truck, starting with the bottom one (see above). Then we held the wing in place and screwed the top end to the the upper tie-down. Larry also brought rope to reinforce the blankets as a backup support. They travelled just fine, without a scratch.

After hanging the wings, we used a "skid loader" (short bucket tractor like a Bobcat) to lift the fuselage using a chain and the engine mount. Several local volunteers were quite willing to help get the plane in the trailer also, especially Mike who lives in the house nearby. Larry Flesner flew into West Bend (the nearest town) to see what he could do, and Mark Jones volunteered to drive down also, but we already had it under control at that point. Thanks for the offer, guys.

Notice how tight the fit was. The rudder was cranked all the way over to allow the wheels to fit within the box. The horizontal stab was within a quarter inch of the wing. Despite all the really rough northern roads (especially around Chicago) and the 800 miles of travel, I never had to retighten the ratchet straps, and nothing moved...not even an eighth inch. It was simply frozen in space in the back of this truck!

The key to all of this was a few 2x4's that trapped the tires. No screws were needed into the floor, which is a good thing because it was aluminum rather than wood. The ratchet straps pulled the gear aft, but the 2x4's were wedged against the back of the truck and couldn't move. It was a brilliant strategy that Larry came up with, and is a model of how to do this for others. When putting the plane in the truck, there was only about a quarter inch on each side for clearance between the wing attach fittings and the door opening. These are the standard 84" wide spars and WAFs, so all KRs with plans-built stub wings should fit.

All packed up and ready to go. Note strips of Styrofoam between wings and side rails...donated by Mike, along with the 2x4's and 3/4" strips used to wrap the blankets around to hang the wings.

Here's the crew that made it happen. Composed of the very helpful locals, including Edgar the landowner (and skid-loader provider), and Larry Howell and Mike Young, both on the right. Every downed pilot should be so lucky! I should also thank Jesse the deputy for all of his help, from bottled water to directions to Sandy's for the best lunch in town!

The plane is back in my hangar, but it will be a while before I dig into the engine. At first glance, the hole in the top of the engine case indicated a broken rod bolt or spun bearing. The piece of aluminum on the right has an imprint on it that I'd later know was from the imprint of the rod bolt threads. I've rebuilt a lot of VW engines over the years (I was a VW mechanic at a dealership before going to school at Auburn), so this is not my first rodeo. I rebuilt my first VW engine (for my new '74 Karmann Ghia) at 18 years old. And I've never had a problem with an engine that I built until now (other than broken crankshafts, which I attribute to "Corvair flight performance envelope research", rather than anything I did to cause them.

The oil pressure and temperature were perfectly normal when this happened, I had no idea it was coming. I had the engine completely apart just a few flying hours before this flight to replace a broken head stud, and the "old" bearings (which I replaced with new ones anyway) looked great. Before takeoff from OSH, I checked the oil and it was right on the full line, and I had readjusted the valves before leaving home 6 flying hours before the failure, and there were no surprises (overly tight valves). I spun the engine over by hand several times before departure from OSH, and there was nothing tight about it, with even compression on all cylinders. There were no oil leaks, until the hole in the case! By the way...the appearance of mismatched rod caps isn't what it seems...they are a matched set, and are not mixed up...just renumbered somewhere along the way for some reason (they came this way with the engine).

When we unloaded the plane from the U-Haul back at the hangar, we found the valve head on the floor near the open door. As far-fetched as it may seem, I think it worked its way out the exhaust system on the ride home, and remained on the floor, despite the open door. The valve collision with the piston likely bent a rod which punched the hole in the tightly clearanced engine case. The valve head was actually rolled, as if forged into the curved shape by a piston pin. I later verfied that it will indeed fit through the exhaust port and the exhaust system as well.

Entries in the engine logbook indicated a new pair of heads at about 200 hours, a "valve job" at 250 hours, and I rebuilt the engine at 320 hours after the spun bearing (I'd put about 12 hours on the plane since I'd bought the plane), installing a set of forged stainless valves (standard fare, if you want your valves to last). I also reground the seats and lapped the valves, and started thinking about a new pair of heads. Over the next year I bought a pair of dual-plug VW heads, based on CB Performance CB1 heads, but didn't think much of their casting quality...lots of casting flash, and poor quality throughout. It turns out that good quality cylinder heads for the VW are difficult to find these days.

I was still considering other cylinder head alternatives, when about two weeks before OSH, a head stud broke. First time I'd ever seen that, on a VW or a Corvair. So I was short of time when I had the engine apart to replace the broken case stud at 430 hours, and I didn't have time to work out the dual ignition system and valve train geometry of a new pair of heads and still make it to Oshkosh. But I did feel the need to disassemble the heads and clean the lead deposits out of the chambers, ports, and valves, as well as cleaning the deposits off the piston tops. While I had the heads apart, I lightly refaced the seats and relapped the valves (all valves were returned to their original seats, using the same springs and keepers), but I will say that I was amazed at the degradation of the valve seats during the previous 110 hours since I'd recut them. My guess was that the high CHTs I was seeing were "cooking" the seats before their time.

Those valves had only 110 hours on them, which is practically new. Although sucking an exhaust valve in high-time air-cooled Type 1 engines is not uncommon, I have never heard of this happening in VW powered was completely off my radar. In cars, the usual mode of failure is high mileage, neglected (and therefore misadjusted) valves, high heat transfer into the valve stem, and failure inducing valve stem stretch after a long hard climb and subsequent high-vacuum situation caused by coming down the other side of the mountain. I wouldn't have thought 110 hours would be in the danger zone for such a thing happening in an aircraft application. And in the 120 hours that I've flown the plane, I have not discovered tight valves that would indicate a problem. Apparently I was wrong. Now that this has happened, Steve Bennett tells me that he recommends customers throw away the entire valve train between 200 and 250 hours! He also said he'd only seen one other exhaust valve fail that caused catastrophic engine failure, and that was in Art Franks' Aerovee engine with 310 hours on it.

I think the take-home from this it to ensure that you are running forged stainless steel valves from a reputable source, and to immediately replace any exhaust valve that isn't stainless. A lowly exhaust valve of questionable quality killed the whole engine! The new engine has a set of "SINUS" forged stainless valves from Israel in it, which appear to be high quality and have a good reputation.

I've never heard of a Corvair aircraft engine sucking a valve, and there are a lot of Corvairs flying with three to four times those hours on the valves. But then again, my experience is that the VW installation on this plane runs 100 degrees hotter than the Corvair in N56ML. There is way more fin area on a Corvair head than a Type 1 VW head (Type 4's are better). One of the things I was planning on doing this winter was to fabricate and install cooling plenums on the engine similar to what I did on my Corvair, which lowered engine temps about 50 degrees over a more typical baffled installation (in a direct comparison with a similar engine without plenums). I'd have done it already, but wanted to establish a "baffled" baseline before I swap out to plenums, so I could quantify an exact temperature difference.

By the way, I was not injured in any way...not a scratch, an ache, or anything other than damaged pride that somehow an engine that I built had a failure that was completely unexpected. The airplane did pretty well also. The KR is a tough little bird. Had this been a tube and fabric plane, there would be a lot of wood and fabric repair to be done. This one just needs a good wash job and the tail wheel support area repaired, which a little T-88 will take care of with a couple of hours of work.

I have to admit that when it was all said and done, the day was kind of fun, and certainly an adventure. Thanks again, kind folks of West Bend!!

October, 2015 UPDATE -

So I finally got around to tearing this engine down, and here's the aftermath. Quite impressive, I'd say. Zillions of piston pieces everywhere, twisted and bent rod, rod nut split into three pieces (this is probably what poked the hole in the case), and the cylinder fell apart after I unscrewed the nuts holding the head on. The only thing holding it together in this photo is the steel cylinder spacer on the far end. The cam broke into three pieces. The inside of the case was not a happy place either. Quite a mess! It could have been worse though...if there had been nuclear material involved! The amazing thing is that it took almost 10 seconds to come to a complete stop. Those other three cylinders were working pretty hard to keep the grinder going.

Before people start conjecturing that the cause for this was something else, this was a sucked valve, not a broken rod bolt, broken cam, or anything but a valve head that came unglued. I've looked it over pretty well, and that's the only plausible explanation, and where all the evidence points.

I've just finished building a new engine. Well, not entirely new...I was able to reuse the distributor drive gear, but the rest is toast, or of dubious suitability for an airplane engine.I expect to have the plane back in the air this weekend.

Why couldn't I have been as lucky as the young lady whose engine I rebuilt in college? She presented this Beetle that she said hadn't "run quite right" for several months. I quickly determined it had a dead cylinder by removing spark plug wires, checked the compression, and got nothing on that cylinder. I tore it down and found similar damage to the head, and the valve head was long gone, but the piston and rod were still intact, happily pumping air in and out. Go figure.

On the way up to OSH, I noticed the CHT for one of the cylinders slowly but steadily climbing, and it was alarming enough that eventually we (Larry Flesner and I) landed to check things out somewhere in northern Illinois. Now that I think about it, it was cylinder #4. I pulled the valve cover and checked the valve adjustment for the number four cylinder, by getting the engine up to TDC for that cylinder, and then ensuring that both valves had a reasonable amount of freeplay, and could find nothing wrong. We also pulled the plugs, which looked fine (they were practically new), but swapped holes with the plugs AND the CHT probes, between #3 and #4, just to see if the CHT numbers swapped locations with the probe change.

On takeoff, #4 CHT wasn't reading at all after that, and now I know why...the ring terminal was loosely crimped and wobbling around to the point of no contact, somehow. There's nothing magic about that's just a large diameter wire terminal that's crimped around the thermocouple joint and transfers heat from the head to the thermocouple. The engine was running fine, both before and after the landing, and the CHT for number four was reading ambient, so then I started suspecting the iEFIS. After all, my MGL iEFIS CHTs are always bouncing all over the place, so the only thing about this is that one of them was slowly climbing. So I lulled myself into thinking there was no problem after all. Not true! Thermocouples never just start gradually reading high...they don't work that way, and I knew that.

#4 is the one that came apart after climbing out of Oshkosh airspace. I'd originally thought the valves were old, but then I was looking through my original rebuild of this engine when I first got it, and there they were...all new forged stainless valves (see the first engine rebuild details. Well at least I was smart enough to replace all the valves in my original rebuild of the spun bearing enginem but it worries me that I second guessed myself and assumed that I hadn't installed new valves. But after looking the broken valve stem over carefully, I noticed TRW stamped on stem near the keeper. And then it came back to me...when I had the engine apart to replace the broken head stud (that's another story) I had replaced one valve because the tip was starting to dish, probably because one of the "ball foot" adjusters had gotten turned around and was a single point of contact, rather than a flat surface.

So I went to my box of VW valve train stuff, and dug out a baggie of 8 valves from a previous incarnation of the Karmann Ghia engine, probably 30 years old. The valves looked great, but were not stainless. They were aftermarket TRW (given that they are oversize...35.5mm intakes, in a stock application), swapped out many years ago during some previous engine rebuild. So I picked out the best one and swapped out the stainless valve with the dished tip with one of the TRW valves. I planned on swapping out both heads after I got back from OSH, and surely this valve wouldn't present a problem with a few more flight hours on it, right? This was likely a two-piece valve, and I have no idea why it only lasted a few flying hours after installation, unless some kind of weird metallurgy took place over those thirty years to weaken it, or maybe I'm just really unlucky. I'm starting to wonder.

Well, four months later I'm finally back in the air again with what is essentially a completely new engine, and it's nice to be back! I'd much rather be flying behind a Corvair though...

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