Catastrophic engine failure today in flight

[Guest]

Jose,

The clean up job on the oil was most impressive.

No washers are installed under the nuts on connecting rods.

I seriously doubt that one could over torque the bolt to the point the shank would failed before the threads of either the nut or bolt would fail.

[jetdriven]

That would explain the oil pressure going to zero before it got real. Hopefully the cause can be found.

[N601RX]

These are a stretch bolt. There is a wide torque window, but a very narrow stretch length you have to hit. Lycoming also manufactured some rods that are machined for a .005 oversized bolt.

[Piloto]

Jose,

The clean up job on the oil was most impressive.

No washers are installed under the nuts on connecting rods.

I seriously doubt that one could over torque the bolt to the point the shank would failed before the threads of either the nut or bolt would fail.

 

You are right there are no washers used for the rod bolts. Washers are sometimes used in applications to keep the nut from getting into the shank. As you mention is hard to break a bolt by over torquing but I have seen it, in particular on brass bolts. It all depends on the bolt material. The over torquing combined with the engine temperature may have tiggered the failure. In normal operation the rod bolts are not subject to tensile force except on the intake stroke and is minimal. The fact that the engine failed after 30 minutes on its first run led me to believe that this was a reassembly issue.

 

José  

[takair]

The nut looks like it is only tightened to the locking portion. (Assuming that is how it was found). Is it possible it was installed and never torqued? That would explain the worn threads and possibly even the stretch, as it hammered back and forth. Would be great to see tear down photos of the rod and the other bolt.

[manoflamancha]

Wowzer! Great job on the emergency landing and glad to hear you made it back ok. Sorry to hear about the engine. Hopefully you get her all fixed up good as new.

[The201pilot]

Visited the engine shop on Friday.  The installing shop is going to remove the engine and deliver it to the engine shop for teardown on Tuesday.   We do have a couple options now, one would be to have the engine replaced with the 2 separate mags (A3B6) i believe is the number.  Thanks all for the praise.  

 

Clarence,

 

There was a small layer of oil on the inside of the cowling.  The case was not cleaned before any photo's were taken...the rod cap bolt in the picture was pulled out of the hole with the set of pliers you see in the photo...it was literally just sitting in the hole of the case.  There was oil all down the belly of the plane, i don't believe the case is empty of oil...As i said in the beginning of this post,  there is no witch hunt here, as a Millwright I understand machines fail, wether or not it was a part failure or human error in assembly procedure, lets tear it down find the root cause, and fix it properly so I can go flying ! 

[pinerunner]

As everyone else has said. great flying. Great glide ratio is one of the reasons I got a Mooney.

 

This must be precisely what the mechanic carries insurance for since you couldn't have a better smoking gun whether it was human error or a faulty part. Catastrophic failure within hour into test flight. They'd have to be crazy if they try to charge you more for making good on this. So they sent it out to a specialty shop that overhauls engines? Makes you wonder. My father had an A/P and flew thousands of hours behind engines he overhauled himself. Only way he could feel comfortable. If you can't do that I almost think you should shop for your mechanic before you buy the plane.

[DaV8or]

Great job 201pilot! This failure illustrates why there is the debate between automatically rebuilding at TBO vs. operate on condition. Infant mortality of new/rebuilt engines is significant.

 

I have to ask, have you been conscience of the risks with new engines and planned all your routes accordingly, or you just got luck with the nearby airport?

[The201pilot]

This is the second time i've "test" flown a new engine. (in the short time i've been involved with aviation)  The first time i did circle the field for about an hour before venturing off.  This time however, i did not circle the field, but instead had small airports and grass runways all along my route. Also with a planned altitude of 7500' it did give me some gliding distance.  The failure just happened to be at the perfect altitude from a field about 9 miles away and the engine did keep spinning for a little while...although not making power, i'm sure it helped.  I was not 100% prepared for this failure.  Any one rarely is.  However, life is a learning experience and during the next engine "test" flight I will be circling the airfield for as much time as necessary for me to gain confidence in the new engine.  Anything over the 15 minutes this one lasted should be good !

 

m.

[Guest]

Hi Martin,

I've never suggested you're on a witch hunt, certainly some of the other posters are.

I'm just thankful that you're fine and your plane will live to fly again. Hopefully once removed and disassembled there will be an explanation of the cause.

Clarence

[yvesg]

Even after an annual I would stick around the airport for a bit. However the field I take off from is near a small town and the country all around is full of emergency fields AND frozen rivers...

Lets hope that your plane is ready for the upcoming Mooney Caravan :-)

Yves

[pinerunner]

Hi Martin,

I've never suggested you're on a witch hunt, certainly some of the other posters are.

I'm just thankful that you're fine and your plane will live to fly again. Hopefully once removed and disassembled there will be an explanation of the cause.

Clarence

 

I don't know if I'd go so far as to call it  witch hunt but I'm very interested in who ends up footing the bill for setting this to rights. I know part of the expense with my mechanic is for his expensive insurance. I assume that covers cases like this one and that a reputable shop would eat the expense while a small one would try not to and run the risk of being sued. It's hard to believe its just be a coincidence.

[The201pilot]

Ok so we have a solution.  We're going to replace the engine with a Factory overhauled A3B6 (instead if my old A3B6D)...The shop we be paying for R&R of old to new, and more than half of the cost, pretty much equal to what my old engine would have cost to replace...approx 20,000 CAD..

 

I'm happy with this solution, I believe its fair, but they still haven't found a root cause on initial oil pressure loss.

[Piloto]

Ok so we have a solution.  We're going to replace the engine with a Factory overhauled A3B6 (instead if my old A3B6D)...The shop we be paying for R&R of old to new, and more than half of the cost, pretty much equal to what my old engine would have cost to replace...approx 20,000 CAD..

 

I'm happy with this solution, I believe its fair, but they still haven't found a root cause on initial oil pressure loss.

 

When the rod cap is open the oil in the cranckshaft is no longer contained under pressure, so there will be a pressure drop prior to engine failure.

 

José 

[The201pilot]

Seems logical enough Jose, i wasn't sure losing the one cap would have been enough to lose all oil pressure. 

[The201pilot]

The new engine has been hung and ground tested, should be able to get her out for a test flight and start breaking the new engine in next Wed. Aug13/14...

Keep ya'll posted on the flight, and performance of the new engine.

 

M.

[jetdriven]

Ok so we have a solution.  We're going to replace the engine with a Factory overhauled A3B6 (instead if my old A3B6D)...The shop we be paying for R&R of old to new, and more than half of the cost, pretty much equal to what my old engine would have cost to replace...approx 20,000 CAD..

 

I'm happy with this solution, I believe its fair, but they still haven't found a root cause on initial oil pressure loss.

So how much are you paying and how much are they paying? #confused

[cujet]

I certainly hope you replaced the oil cooler (they fill with metal particulates) and the oil lines are known to be clean. 

[jlunseth]

I had a similar event a few years ago over Canada.  When I landed they had fire trucks adjacent the runway.  We pulled into the ramp with oil dripping off the entire bottom of the aircraft, and one of the firemen

shook my hand and said "Nice job, Captain."  I guess that is about the nicest compliment about flying ability I can think of, so though I can't shake your hand from here - Nice job, Captain.

[The201pilot]

C-GLWJ is happily back in the air again.  Everything working properly, minus some tweaks with the prop governor at high RPM... I managed to make it out with a factory engine and a bill "for original repair" plus a difference on the new engine and of course some extras..(as always) ended up writing a cheque in the high 30's...wether or not you feel this is an exorbinent amout or you could have "gotten it for less" I'd rather not hear about it.  I am happy with the service and fairness I recieved from all those involved and do not wish to hash through the exact amounts.

 

I do however want to say thanks for the compliments, well wishes and so fourth...we'll see you in the skies !

 

Marty

[Immelman]

Marty, I am glad to hear your airplane is back together and running well. A belated job well done, sir, and enjoy your factory engine

[N177MC]

Was the "probable cause" of the engine (con rod) failure determined ?

[The201pilot]

From the evidence inside the engine, what was left..oil starvation was the cause..with failure beginning on the firewall side of the engine and proceeding towards the spinner..but the root cause of the oil escaping from the from the engine was not determined.  

 

Marty..

[Awqward]

Have a read of this....may be relevant...

http://www.casa.gov.au/wcmswr/_assets/main/airworth/awb/85/014.pdf

Check whether the tappets were the improved p/n....