Do Not Stray far in PHASE I

July 18, 2015
Guys,




N721WD at start of Phase I.

This is my story.

*I took-off at 9:30 local time on May 30, 2015 *for more Phase I hours (The Hobbs was 16.8 at takeoff). *My flight plan was to check out the AP systems and record cruise speeds at 5000 Ft. *

I activated the Dynon AP at 5000 Ft for the first time and it just worked. *I tried LEVEL , TRK & ALT and 180 Degree turn and everything worked as advertised.*

Since I had the AP working, I set up a racetrack parallel to the 22/04 runway at KMMV, *offset about 5 miles to the South. *I would fly west on a 220 TRK (Track) then hit the 180 *button (Reverses the Track 180 degrees) and fly back on the 040 TRK , repeat, repeat. *I set the rpm to 2200, allowed the AP to stabilize and recorded air speeds and fuel flows, repeated several times in a circuit then increase to 2300 rpm and repeat, then at 2400 rpm, then at 2500 rpm. *

I was nearing completion of the day and starting the final set of 2500 rpm laps, when all **** broke loose. *There was a loud bang and every thing started shaking violently. *
My Instructor?s training was to first point the nose to the nearest field, then go to Idle and finally establish best glide. *Then start to worry about what happened. *In less than 30 sec *Oil Pressure was at near zero . *I was still at speed and the prop was windmilling at about 2000 rpm. As the field looked far away, I increased the throttle to maintain the 2000 rpm and decided to let it run as long as it would and hoped it would not freeze up before I was down. *

The 35 runway at KMMV was nearly a straight shot from my location, but approximately five miles away. *I knew it was going to be close, but by increasing power to maintain the 2000 rpm it worked out. *I kept power on until I had the runway made, *then started dropping the flaps and touched down. *The engine did not freeze up. *When I stopped and got out, *oil was pouring out of the lower cowl. * After pulling the upper cowl the two large and gaping holes in both sides of the crankcase were very obvious. *The crankcases, the cam, the connecting rod for #3 all appear to be trashed. *I found several metal chunks on the Cyl fins. *Something flew out hard enough the break the Lightspeed ignition coil case which was mounted above the engine.*


Note: The crankcase hole beside the #4 Cyl.





Note: The hole in the crankcase above the #3 Cyl.



http://kmmvphoto.smugmug.com/photos/i-CN8nHwk/0/M/i-CN8nHwk-M.jpg
This photo shows the failed end of the Connecting Rod bolt. *Because the bolt backed out ~1/4 inch the failure plane is difficult to photograph.




This Photo shows the Connecting Rod Bolt that has backed out ~1/4 inch. *The photo is taken through the crankcase hole over #3 Cyl.
Note the remaining stub of the missing Connecting Rod ~ 1 inch tall.

Total Hobbs 18.4 hours at the end of the flight.




N721WD after the May 30, 2015 engine failure. The engine has been removed to return to Lycoming.

*It appears the #3 Connecting Rod Failed at 2500 rpm in level AP controlled flight. *I had been at 5000 Ft at 2500 rpm for ~ three minutes since the last control input by me. *

Bill

So sorry about the blown powerplant, and kudos on keeping your cool and returning her to earth safely. And so fortunate that this didn't happen on climb out at 250 ft. AGL. Is your engine a new Lycoming, or factory rebuilt?

Wow

Yes, holy cow and kuddos on keeping your cool to get her and you down safe. Well done.
Please keep us posted.

Serious test pilot . .

Wow, photos worth the effort. Great job getting that plane landed safely. Was this a new engine, it does not look like the factory Lycoming paint color?

That's only just over 3.2 million cycles, assuming 2 hours of bench running. Certainly appears to be a fatigue issue, maybe a heat treat problem. It is a good reminder the reason for 50 hours in phase one. 50 hrs would be about 8 million cycles, and if steel makes it that far it will is unlikely to fail.

Keep us posted on the results, if it is heat treat, then it is unlikely to be the only one.

Great job getting her down safely!

Very well done.

The Engine was a new Lycoming Thunderbolt with about 20 hours since new.

Lycoming is building up a new Warranty Replacement engine. The new engine in due to ship in late August.

At least Lycoming is jumping to the rescue! That is good to hear. As if they will provide the metallurgy report when done for your confidence in the next engine.

Thanks for sharing this, I had been thinking about the glide cone over the field, but just for the first few hours. An internal failure possibility had not crossed my mind, and I am a former engine guy. You have reminded me of the early hour fatigue failure possibilities, and quantified why the 50 hours is important with a new engine.

Lucky you had some power left and it was not a total blender inside. It is easy to imagine severing the camshaft and rendering an engine powerless with all those chunks banging around in there.

Would you suggest a conservative glide ratio for early flights ? CS - Prop.

Was the engine an O-233? The cylinder base flanges look to be scalloped for weight reduction.

enlightenment please

Whd721 - great job on getting down safely. I've had one event years ago of loss of power with a semi-violent shaking engine and it scared the heck out of me. Got down safely but 5 minutes seemed like 5 hours.

BillL said:

Certainly appears to be a fatigue issue, maybe a heat treat problem.

Click to expand...

Connect the dots for me. What do you see to led you to those causes? How can something with low cycles suffer fatigue failure without abnormally high stress. I am thinking about a classic s-n fatigue diagram. If the designer does it right he has "s" low enough that "n" is essentially infinite. It can't always be done given other constraints but with all the thousands of hours most Lyc's run without catastrophic failure I don't see how this could be fatigue unless the root cause was another defect that either sifted "s" higher on the curve or created a crack initiation site or other failure point specific to that component on that engine.

I hope it is not a heat treatment problem because that could mean a batch or even multiple batches of parts have the same issue.

Man, you did a great job making good decisions and flying the plane.

I learned from this - thanks very much!

Dave

Thanks for the well written report William. You did a great job managing this serious in flight emergency.

There is an old proverb about the first few hours of a new engine, don't stray too far from home. You sure proved it.

That being said, someone at Lycomong screwed up with this engine. I know of one other new engine that had an early valve failure, makes one wonder how come?

FWIW I do not regret going with BPE. They assemble an engine with care and precision. It costs a little more but you get what you pay for.

Lycoming is a good company but this failure should not have occurred. The replacement engine will be ok, they will put it together with great care.

Bubblehead said:

Connect the dots for me. What do you see to led you to those causes? How can something with low cycles suffer fatigue failure without abnormally high stress. I am thinking about a classic s-n fatigue diagram. If the designer does it right he has "s" low enough that "n" is essentially infinite. It can't always be done given other constraints but with all the thousands of hours most Lyc's run without catastrophic failure I don't see how this could be fatigue unless the root cause was another defect that either sifted "s" higher on the curve or created a crack initiation site or other failure point specific to that component on that engine.

I hope it is not a heat treatment problem because that could mean a batch or even multiple batches of parts have the same issue.

Click to expand...

My thinking - not gospel - yes such low cycles would mean over stressing, the fact it waited a while indicates that it either a. had a defect, b. under stressed so that stress cycle (low side) was closer to a zero stress (bad as you know) or c. the fatigue strength of the fastener was too low. Poor heat treat, too long in the pickle tank, bad machining that was burned down during heat treat, bad quench, inadequate annealing - all lumped into "heat treat". Possibly too brittle, and more susceptible to fatigue crack growth.

Indeed, I too, hope it is not a processing issue as it surely won't be the only one. If these bolts thread into the rod, let's hope it was a thread issue that allowed full torque from the torque machine, and it just had inadequate preload, resulting in near zero-to-max stress range that prematurely failed it. If the rod design is threaded, then this is more likely than heat treat. In high volume production, this is the highest probability occurrence for an inadequately loaded fastener. I am assuming that there is a machine that automatically torques both rod bolts simultaneously.

A story - during an assembly line tour at a truck plant in Japan, after the powertrain had been set into the frame and just before the cab was lowered on the chassis, 4 guys with what looked like tack hammers just attacked the chassis. Every bolt head was smacked with the hammer. A bolt that was torqued but had a thread issue (bottomed etc) preventing proper stretch load, would sound tack and not tick when struck with the hammer. I was amazed at such a practical approach to the issue and 100% of the critical fasteners were checked in 30 seconds. End diversion.

Wow

Nicely done Bill - way to keep your cool!!!

BillL said:

......
Indeed, I too, hope it is not a processing issue as it surely won't be the only one. If these bolts thread into the rod, let's hope it was a thread issue that allowed full torque from the torque machine, and it just had inadequate preload, resulting in near zero-to-max stress range that prematurely failed it. If the rod design is threaded, then this is more likely than heat treat. In high volume production, this is the highest probability occurrence for an inadequately loaded fastener. I am assuming that there is a machine that automatically torques both rod bolts simultaneously.
.....

Click to expand...

No "two bolt torque" machine mentioned in the Lycoming overhaul manual re-assembly section.

The rods are not threaded - the bolt slips through holes in the rod and the rod cap and is secured by a nut.

My understanding is that the con rod nut is a one-use nut and pricey.

This is not the firstfactory lycon with infant mortality I have heard of. I know a guy with an rv8 who had under 100 hrs on his. He was flying with his daughter and the engine sound changed eeeeever so slightly. He was flying by a good sized airport and he told me that had he been alone he would have just pressed on, but the presence of his daughter made him point towards the airport. A couple of minutes later the prop froze. The engine discombobulated itself internally. He had the height and speed to make an uneventful deadstick landing.it was a mfg defect and lyc replaced it.

He now has 1900+ hrs on it and will overhaul and put another 2000 hrs on it. He loves the airplane.

Very happy that you and your new plane are safe. Yes you are more important but anyone who puts that much of their life into a project would be heartbroken to wreck it. Nice job.

I'm glad you got all of this posted successfully, Bill! This is a front-page story, for sure, and I'm sure it will get a lot of attention and comments, and for everyone's safety, that's a good thing!

az_gila said:

No "two bolt torque" machine mentioned in the Lycoming overhaul manual re-assembly section.

The rods are not threaded - the bolt slips through holes in the rod and the rod cap and is secured by a nut.

Click to expand...

I meant for the factory assembly. Maybe the production volume is not high enough to justify. Thanks for the info on the bolt/nut design. Then - back to heat treat or just bad assembly.

sblack said:

This is not the firstfactory lycon with infant mortality I have heard of. I know a guy with an rv8 who had under 100 hrs on his.

Click to expand...

Unless I missed something, this was not a Lycon engine. It was a Lycoming. Two different companies.

There are 2 bolts for lyc rods. One is single use stretch to torque length. More common is the standard torque to ft/lb bolt. Could be it just never got torqued. You snug up the pair first to ensure fit, then torque.

aerhed said:

There are 2 bolts for lyc rods. One is single use stretch to torque length. More common is the standard torque to ft/lb bolt. Could be it just never got torqued. You snug up the pair first to ensure fit, then torque.

Click to expand...

Much more that two....

http://www.lycoming.com/Portals/0/t...I 1458F (03-06-2012)/Connecting Rod Bolts.pdf

However, if it was a "didn't torque" problem - that's pretty bad for an initial factory assembly process whichever type of bolt was used....

You were fortunate the engine stayed together and continued to produce some power. Great job in getting down safely.

It certainly sucks when something like this happens but at least Lycoming sounds like they will be doing something for you.

As I've said before, it doesn't matter what's stamped on the valve covers. Any engine can fail and do. Lycomings are no different, you can find multiple examples in accident reports.

I find many flying single engine aircraft believe it won't happen to them but the risk is always there, small as it may be statistically.

Fly smart and keep your forced landing skills honed with some practice several times per year.

Under and over torquing rod bolts/ nuts is a leading cause of just-built engine failures. Seen a number of examples over the years (not on my builds). Usually more catastrophic than this one. Me thinks form the videos I've seen, that these are hand torqued at the factory.

Will be interesting to see what Lycoming says when they examine the pieces. A material/ batch defect could have far reaching consequences for others with the same engine.

Man, that's scary.

I have just completed about 9 hours on my -10 and the thought of something like that happening makes my skin crawl.

Excellent job getting her down and hopefully the next engine will be better! Does the warranty include a new pair of underpants?

To have chosen the YO-233 you must have been trying for a quite low empty weight. What did you achieve?

Welcome to VAF!

Philip---------welcome aboard the good ship VAF