In-Flight Engine Failure

"Dave Stadt" wrote in message m...

There is no such requirement. Even if there were such a requirement there
is no guarantee the engine teardown would be done. Just because there is no
prop strike in the log book does not mean it did not happen.

There is no regulatory requirement, but both Lycoming and Continental "require"
a tear down inspection after any sort of prop strike. For us small operators, it's
just a very strong suggestion from the manufacturer. After my engine failure which
had a very small scuffing of the prop blades, the insurance company didn't even bat
an eye on paying for the teardown. Ran about $3K if I recall.

"G.R. Patterson III" wrote in message ...
"O. Sami Saydjari" wrote:

Is there a way to test a crank after a prop strike to absolutely assure
that it has no micro-fractures or hidden fatigue points?

Yes. IIRC, it's called magnafluxing.

George Patterson
If you don't tell lies, you never have to remember what you said.

I've wondered about this. Mangnafluxing will detect cracks. Will it
positively detect damage from a prop strike that might cause a failure
much later?

I've always been nervous about this WRT factory re-man engines. How do
you know for sure that there was never a prop strike?

Incidentally, on the subject IO-360 engine, is there an improved crank
like there is for the IO520s that has the fillet at each cheek? On the
520s, those are the 520BBs; without the improved crank, they were -B or -BA.
I know there were failures with the older design.

In the Bonanza & Baron Proficiency courses, we've flown about 80,000 hours
and have had 7 engine failures AT THE CLINICS! These aren't doggy airplanes!
It's made me much more conservative. Fortunately, only one resulted in injury.

Bill Hale

Updated update: I was just down at the overhaul shop today )Poplar
Grove). The crank broke just in front of the rear main bearing. So the
front 5 cyclinders were running the prop and the rear-most cylinder was
running the gearing to the rest of the engine. They said the whole shop
stopped to come take a look at the engine! They were astounded that it
ran 10 minutes after the crank broke (which is exactly the time I needed
to get to the nearest airport and land safely).

The collateral damage was minimal. Some gear teeth on the back of the
crank need replacing because they got worn from the crank wobling (so
they will just relace both gears). Similarly, the rear bearing is shot,
and the place where the bearing sits needs to be welded and resurfaced.
The cam shaft got a little bit of wear on it from a piece hitting it.
One cylinder is stuck as a result of some of the wear, but they think
they can get it out without problem.

Theories on cause? Well, so far, the shop thinks that maybe it was
overboosted before I got it. On the last one of these failures they
saw, he said the overboost relief valve was stuck and did not perform
its function. He said that these valves are rarely checked on annuals
(if ever). He has no alternative theory at the moment. We will have to
check the valve later because it is still with the plane out in
Gaithersburg, MD.

So, it looks I need to buy a new crank shaft and some other minor parts.

The shop visit was very interesting. I learned a lot and the folks at
Poplar Grove (Ill.) seem really on top of things. Their shop seems top
notch. I got a great tour.

I took pictures of the broken crank shaft. I will try to post them to a
web site in the next few days and post a pointer to them.

At the end, one of the shop workers suggested that I immediately go out
and buy a lottery ticket, because luck was definitely with me.

-Sami
N2057M, Piper Turbo Arrow III


O. Sami Saydjari wrote:
Update: The crank shaft broke! That means I was operating on just a
couple of cylinders. The overhaul folks said that have only seen this
happen one other time; apparently it is quite rare.

I am going to visit my engine tomorrow to see the damage for myself, see
if we can conclude what caused it, and learn as much as I can from
seeing my engine splayed out on a workbench.

Seems like a great learning opportunity. Any suggestions on good
questions to ask, or something special I should try to learn from seeing
my engine in this state?

-Sami
N2057M, Piper Turbo Arrow III (in surgery)

OK. Here are the pics for those interested. They are at:
www.swc-alps.org/DSCN3368.JPG
www.swc-alps.org/DSCN3370.JPG

-Sami
N2057M, Piper Turbo Arrow III

O. Sami Saydjari wrote:

Updated update: I was just down at the overhaul shop today )Poplar
Grove). The crank broke just in front of the rear main bearing. So the
front 5 cyclinders were running the prop and the rear-most cylinder was
running the gearing to the rest of the engine. They said the whole shop
stopped to come take a look at the engine! They were astounded that it
ran 10 minutes after the crank broke (which is exactly the time I needed
to get to the nearest airport and land safely).

The collateral damage was minimal. Some gear teeth on the back of the
crank need replacing because they got worn from the crank wobling (so
they will just relace both gears). Similarly, the rear bearing is shot,
and the place where the bearing sits needs to be welded and resurfaced.
The cam shaft got a little bit of wear on it from a piece hitting it.
One cylinder is stuck as a result of some of the wear, but they think
they can get it out without problem.

Theories on cause? Well, so far, the shop thinks that maybe it was
overboosted before I got it. On the last one of these failures they
saw, he said the overboost relief valve was stuck and did not perform
its function. He said that these valves are rarely checked on annuals
(if ever). He has no alternative theory at the moment. We will have to
check the valve later because it is still with the plane out in
Gaithersburg, MD.

So, it looks I need to buy a new crank shaft and some other minor parts.

The shop visit was very interesting. I learned a lot and the folks at
Poplar Grove (Ill.) seem really on top of things. Their shop seems top
notch. I got a great tour.

I took pictures of the broken crank shaft. I will try to post them to a
web site in the next few days and post a pointer to them.

At the end, one of the shop workers suggested that I immediately go out
and buy a lottery ticket, because luck was definitely with me.

-Sami
N2057M, Piper Turbo Arrow III


O. Sami Saydjari wrote:

Update: The crank shaft broke! That means I was operating on just a
couple of cylinders. The overhaul folks said that have only seen this
happen one other time; apparently it is quite rare.

I am going to visit my engine tomorrow to see the damage for myself,
see if we can conclude what caused it, and learn as much as I can from
seeing my engine splayed out on a workbench.

Seems like a great learning opportunity. Any suggestions on good
questions to ask, or something special I should try to learn from
seeing my engine in this state?

-Sami
N2057M, Piper Turbo Arrow III (in surgery)

"O. Sami Saydjari" wrote in
:

So, it looks I need to buy a new crank shaft and some other minor
parts.

Have you checked with your insurance agent on this? I'm wondering what
part of the total cost they will pay, if any. Basically they are on the
hook for any damage which is NOT the original problem. For example, prop
fall off and you make an emergency landing in a corn field, damaging some
aluminum. They won't pay for the prop, but will pay for all damage to the
airframe.

In this case the crankshaft is definitely YOURS... that's what broke. But
I wonder if they will pay for any "consequential" {remember that word}
damage to the rest of the engine?

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

O. Sami Saydjari wrote:
: OK. Here are the pics for those interested. They are at:
: www.swc-alps.org/DSCN3368.JPG
: www.swc-alps.org/DSCN3370.JPG

In picture 3370, it looks like there are two distinct types of fractures.
The top of the fracture, through the vibration damper mounting holes, appears
to be dark and have a rough surface, which typically means a fatigue failure.
The remainder of the fracture has a shiny, smooth surface, which typically
means an instantaneous overload type of fracture.
Interesting.
--
Aaron Coolidge

"O. Sami Saydjari" wrote in message ...
Updated update: I was just down at the overhaul shop today )Poplar
Grove). The crank broke just in front of the rear main bearing. So the
front 5 cyclinders were running the prop and the rear-most cylinder was
running the gearing to the rest of the engine. They said the whole shop
stopped to come take a look at the engine! They were astounded that it
ran 10 minutes after the crank broke (which is exactly the time I needed
to get to the nearest airport and land safely).

How can this be?? The crank drives the camshaft then the mags run from
gears that mesh with the cam gear... at least it's like that on every
other continental I've seen.

So the cam and maqs and oil pump quit working if the crank breaks.

It would windmill, however. Until it locks due to lack of oil.

What don't I understand? If there was metal in the oil filter, the
oil pump must have been running.

Bill Hale

First, I must say that I am not a mechanic by any stretch. I am just
learning this stuff, so I might have misunderstood what the shop was
telling me. Hopefully, an expert will chime in here soon and explain
this a bit better.

That said, I am not sure I understand what is you did not understand.
It seems to me that if the crank shaft breaks, you end up with
essentially two engines: a set of cylinders running one side of the
shaft break and the rest running the other side of the shaft break. So,
it would seem that some cylinders are running the engine parts (oil
pump, magnetos, etc) and the others are running the prop. Of course, if
the break occurs right next to the prop, then the prop would stop. If
it breaks behind the main rear bearing, then all of the engine
accessories stop (and thus the engine stops soon after). Also, I should
point out that the shop speculated that even though the shaft broke,
that in might have been partially connected through friction (since the
break was not a 90 degree shear break).

Now, I will hasten to add that my understanding of crank shaft operation
may be overly simplistic, so again, I will defer to expert opinion as it
comes in. I am sharing all of this to get as much out of it as a
learning experience as I can.

-Sami
N2057M, Piper Turbo Arrow III

Bill Hale wrote:
"O. Sami Saydjari" wrote in message ...

Updated update: I was just down at the overhaul shop today )Poplar
Grove). The crank broke just in front of the rear main bearing. So the
front 5 cyclinders were running the prop and the rear-most cylinder was
running the gearing to the rest of the engine. They said the whole shop
stopped to come take a look at the engine! They were astounded that it
ran 10 minutes after the crank broke (which is exactly the time I needed
to get to the nearest airport and land safely).


How can this be?? The crank drives the camshaft then the mags run from
gears that mesh with the cam gear... at least it's like that on every
other continental I've seen.

So the cam and maqs and oil pump quit working if the crank breaks.

It would windmill, however. Until it locks due to lack of oil.

What don't I understand? If there was metal in the oil filter, the
oil pump must have been running.

Bill Hale

O. Sami Saydjari wrote:
First, I must say that I am not a mechanic by any stretch. I am just
learning this stuff, so I might have misunderstood what the shop was
telling me. Hopefully, an expert will chime in here soon and explain
this a bit better.

That said, I am not sure I understand what is you did not understand. It
seems to me that if the crank shaft breaks, you end up with essentially
two engines: a set of cylinders running one side of the shaft break and
the rest running the other side of the shaft break. So, it would seem
that some cylinders are running the engine parts (oil pump, magnetos,
etc) and the others are running the prop. Of course, if the break
occurs right next to the prop, then the prop would stop. If it breaks
behind the main rear bearing, then all of the engine accessories stop
(and thus the engine stops soon after). Also, I should point out that
the shop speculated that even though the shaft broke, that in might have
been partially connected through friction (since the break was not a 90
degree shear break).

Seems likely to me that the front and rear parts were fairly strongly connected
if you were able to get enough power out of the engine to keep flying for a few
minutes, as I think you said you did. The rear part of the crank would have the
drive gear that turns the cam (and in turn, the magnetos) and the front part of
the engine is not going to make much power unless the cam and magnetos are
pretty well synchronized with it.

It doesn't bother me that part of the shear looks like fatigue cracking and the
rest looks like a catastrophic failure. The fatigue crack weakened the shaft to
the point where it could finally fail catastrophically, no?


Now, I will hasten to add that my understanding of crank shaft operation
may be overly simplistic, so again, I will defer to expert opinion as it
comes in. I am sharing all of this to get as much out of it as a
learning experience as I can.

-Sami
N2057M, Piper Turbo Arrow III

Bill Hale wrote:

"O. Sami Saydjari" wrote in message
...

Updated update: I was just down at the overhaul shop today )Poplar
Grove). The crank broke just in front of the rear main bearing. So
the front 5 cyclinders were running the prop and the rear-most
cylinder was running the gearing to the rest of the engine. They
said the whole shop stopped to come take a look at the engine! They
were astounded that it ran 10 minutes after the crank broke (which is
exactly the time I needed to get to the nearest airport and land
safely).



How can this be?? The crank drives the camshaft then the mags run from
gears that mesh with the cam gear... at least it's like that on every
other continental I've seen.

So the cam and maqs and oil pump quit working if the crank breaks.

It would windmill, however. Until it locks due to lack of oil.

What don't I understand? If there was metal in the oil filter, the
oil pump must have been running.

Bill Hale




--
Dave Butler, software engineer 919-392-4367

Aaaron,
The top of the fracture, through the vibration damper mounting holes,
appears
to be dark and have a rough surface, which typically means a fatigue
failure.
The remainder of the fracture has a shiny, smooth surface, which typically
means an instantaneous overload type of fracture.
Interesting.

Not so much, the fatigue (dark part) may start small and grow until the
"good" material left can no longer bear the load and breaks suddenly (shiny
smooth part)

Regards,

Kai