findings - Pappas Waiex B Forced Landing

[pappas]

Well, the secret is out! I spent half of the day today with the NTSB rep that is handling the engine failure and off-field forced desert landing of my nice Red Aerovee Turbo Waiex B. We met at Air Salvage in Phoenix. After a summary external inspection, we removed the cowl. There was lots of oil in the lower cowl which gave me a start. We could not find any holes in the cases. I remembered that the aircraft was upside down and we determined that it had simply been leaking while inverted.

We knew from the Dynon Black Box data dump that the # 4 cylinder immediately went cold at the moment the engine started to run rough at 2500 AGL. I checked the timing adjustment cap and it was tight and as It was supposed to be. Next, we pulled and checked the plugs, borescoped the new heads and valves, (only 20 hours on the new EMPI's), checked compression, (the engine rotated normally), and all looked as it should. Next, we pulled the #3-4 Valve cover. After about a minute of looking, we noticed that the swivel pad on the #4 exhaust valve adjuster was missing! The NTSB rep found it in some oil in the valve cover we had placed on the table.

There are two swivel pad types on the valve adjusters available for the Aerovee according to the build manual. The swivel pad that came in my engine kit is the pad with a swivel ball with a flat spot, not the large one-piece swiveling pad. There are no apparent side loads or bending moments applied to this component. They only move up and down in a linear manner between the top of the valve stem and the rocker arm end. This one failed and separated from the threaded adjuster stud.

The result was that the #4 exhaust valve was held closed by the valve spring. It could not open to let the exhaust gasses out. We viewed the assembly manual and verified that the alignment of the remaining swivel pads seemed correct according to the images and description in the build manual. He took many pictures and sent me the two that I am uploading.

I believe that with the #4 exhaust valve unable to open, the fuel and air mixture backed up into the #3-#4 intake manifold then into cylinder #3 and caused backpressure into the upstream intake manifold. The resultant loss of power from #3 and #4 was exacerbated with the reduction of exhaust gasses available to drive the turbo. Essentially, I was running on 2 cylinders, next to no turbo, and the situation was deteriorating rapidly. The engine would have failed to run completely in a short period of time.

What is likely a $6.00 part, brought down my lovely bird. The good news is that last week I purchased a partially finished Vans RV7-A kit in California, loaded it in a 26 ft Penske box truck rental, and drove it to my hangar in Phoenix. More good news is that I bought back the salvaged Waiex from my insurance company. I will take the complete Dynon HDX avionics suite including, A/P, Coms, transponder, ADSB, Intercom, knob panels, LED Nav and Pos lighting, LED landing lights, VPX Sport, Tosten stick grips, Ray Allen trim motors, and position sensors.....and stick them all in the new RV7 over the coming year.
It appears I will have quite a few remaining parts, which, somehow, are all in excellent shape, from my Waiex to sell on barnstormers to help offset the cost of the new IO-360 and C/S prop I will need to buy.

All in all, this could have been much worse. The NTSB rep was extremely professional and helpful. He was appreciative that I agreed to come down and go through the engine with him and I was glad he asked. He said the input of the pilot and builder is very helpful to have. I am surprised at how seriously they are taking this incident. No deaths, no damage to people or property on the ground, experimental aircraft, and, compared to most GA events, a relatively low-dollar aircraft. I will update as more info becomes available. Fly safe guys.

[MichaelFarley56]

I think I speak for everyone Lou when I say how glad I am that you are okay after the accident, even if the Waiex isn’t. At the end of the day, you are the important part and we’re all very thankful you are okay.

As for the Waiex, that’s a very interesting on your findings and I’m glad you were able to find the “smoking gun” as to what happened. It sounds like a pretty cut and dried situation, but an unfortunate one. It sounds like there’s nothing you could have done in this case to change the outcome.

Best of luck on the build of the RV, and let us know what parts you will sell. You may have some interest here for some of the parts!

Thank you for sharing!

[Scott Todd]

Great report Lou! So can we get a consensus or have a discussion whether the large one-piece swiveling pad is better? Statistically Lou's failure may be isolated but any identified failure point with a more reliable option is worth looking at.

[gammaxy]

Wow. Thanks, Lou.

You're probably aware from reading the forum that there are now several documented cases of these breaking. Some installed wrong and some, like yours, apparently installed correctly. Looks like there isn't much material where yours broke. I wonder if that is a manufacturing defect? It seems that the depth of the socket would be a critical dimension that could easily eat into critical material. Or perhaps, these are all ticking timebombs.

Coincidentally, the balls on mine started getting loose enough to fall out when I removed the rocker arms to retorque the heads, so I was already in the process of replacing them. With knowledge of failures from this forum, I was trying to find something likely to be more reliable. I don't know how to avoid infant mortality on such a critical $3 part that often needs to be inspected and deburred when you receive it. Whoever makes them is probably not paid enough to care. One obvious option seems to be to use the stock adjusters with no moving parts. I'm not sure how much faster our valve stems would wear, but it seems we'd likely have at least a couple aircraft still flying. I actually really like this idea, but have no experience to understand what problem the swivel feet actually solve.

Not being able to adequately judge the quality of the other chinesium elephant and swivel feet adjusters through the internet, I decided to buy the fancy Porsche adjusters. They look like fine jewelry, have a nice radiused fillet, the pad rotates smoothly, and there's no holes drilled through them. Maybe a satisfied craftsman even inspected them before placing them in the bag.

[karmarepair]

The style of adjuster that failed on Lou's engine: The groove distributes the oil that flows from the cam bearings through the rocker arms.

My Guru on VWs preferred this style (first sourced from the Ford Of Germany Courier engines of the mid-1960's) to the Porsche style Elephants Feet. But he also modified the various components to flow more oil to the heads than stock, regardless of what style of improved adjusters used.

http://bobhooversblog.blogspot.com/2007 ... -mods.html

Bob took .060 off the face of rockers closest to the valve stems to give the adjuster foot a bit of space. Others in various forums speak of doing the same. Particularly with the Elephant's Foot style, and particularly as the valve seat erodes and the valve stems stretch a little in service, this keeps the adjuster from getting jammed against the rocker arm face, another good way to snap the head of it off.

Somewhere else in my correspondence with Veeduber or his published work, he mentions the stock adjusters being a Consumable item like oil or pan gaskets. The conical (about 140 degree included angle) tips would, after about 3 adjustments, become pyramidal, with sharp ridges between the faces that had worn in service. The next adjustment might bring one of those ridges in contact with the valve stem, and REALLY start to tear it up, as well as make more metal to do Bad Things elsewhere in the engine.

[pappas]

My outcome could have been much worse and I am ok with it. It's good to have this forum to share experience and knowledge. I think we are all a little safer because of it.

I should finish the RV in 2022 and fly for a year before Sonex's new high wing comes out! I really like the prelims on that thing. ( When will this building thing stop?!)

I am looking at high-performance competition rocker blocks, arms, and adjusters that are available in the VW Hi-perf world. Billet would be nice! I will likely put something like that back on the Turbo before selling it. At least that is what I'm thinking as I write this.

Damn, that thing was running soooo good for the last 20 hours since changing from MOFOCO heads to the EMPI's. Cool, even temperatures, lots of HP, pulling like a freight train, all the bugs were out. Figures, doesn't it?

[Area 51%]

I abandoned the Empi rockers and adjusters in favor of CB Performance units during the engine build. Didn't think too highly of the bowed pushrods either.