Hit by prop

[gsxrpilot]

Great video Mike!

[carusoam]

For some reason... (a highly worn reason)

I used to check compression on all four pistons prior to starting my O360...

Since we turn the engine off by going to mixture ICO.  it is terribly possible to have left the keys in the both position...

i had 201er remind me one day of things I could do better...

keys out

towbar out

now... don’t touch that... 

It is a challenge being human... MS opens your eyes to a lot of details...

Go MS!

-a-

[carusoam]

youtube link for 201ers video...

 

https://youtu.be/XvgtZ7ztJR0

My hardware is behaving funny

So I copied the link here again

see if that helps...

 

reminder...  click and hold the video until options show up...

select open in YouTube to get the 3D 360 effect.

old new memories... 

great video! 201er!!!

-a-

 

 

[Htwjr]

I have only turned the prop by hand a couple of times in a few years when we were working on the plane anyway. Why is an airplane engine compression checked by compression leaked rather than compression made like other engines?

[rpcc]

for the bad p lead check is it - master off, mags off, mixture cut off?

As for hand propping - that's just silly honestly - do you hand prop your lawn mower?

I don't like touching the thing durring pre-flight never mind trying to pull it through a couple of turns.

[Hank]

2 hours ago, Htwjr said:

I have only turned the prop by hand a couple of times in a few years when we were working on the plane anyway. Why is an airplane engine compression checked by compression leaked rather than compression made like other engines?

What kind of compression readings are you seeing? When mine comes up "78/80," that tells me that 78 psi of the 80 psi introduced didn't leak out. Or am I horribly misinformed?

[Htwjr]

It tells me that as well but my question is why not use a regular compression gauge and turn the engine over to see what it actually produces?  Using the differential test you could get 78/80 with a broke cam or no cam as long as the valves were closed.

[Guest]

3 hours ago, Htwjr said:

It tells me that as well but my question is why not use a regular compression gauge and turn the engine over to see what it actually produces?  Using the differential test you could get 78/80 with a broke cam or no cam as long as the valves were closed.

In an automotive type compression test the engine is turned over with the starter motor. If a turning propeller is a danger, who would want to stand beside the prop while someone else turns the engine with the starter?

An aviation differential check is done with the prop stopped at the top of the compression stroke and allows us to hear where the loss of compression is happening, either from the valves, piston rings, or a cracked head or cylinder.

You're correct that it won’t point out a damaged cam, but lack of power and metal in the oil filter will help find it.

Clarence

[bradp]

Doc - have you experienced the prop kicking around during the compression test? 

[M20F-1968]

On 10/1/2018 at 10:20 PM, aviatoreb said:

It’s a shame these engines don’t have some simply oil spritzer device already built into it whereby a little bit of oil could be drawn up from the case and spritz over the top to drip back down slowlybon it’s own.  Maybe by pressing a button (like the manual rubber prime button on my gas powered tug) or even electronically controlled so it can be done by timer so that it can be timed to keep the engine well oiled during bouts of inactivity.

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned tpo put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Any thoughts?

John Breda

[M20F-1968]

On 10/1/2018 at 10:20 PM, aviatoreb said:

It’s a shame these engines don’t have some simply oil spritzer device already built into it whereby a little bit of oil could be drawn up from the case and spritz over the top to drip back down slowlybon it’s own.  Maybe by pressing a button (like the manual rubber prime button on my gas powered tug) or even electronically controlled so it can be done by timer so that it can be timed to keep the engine well oiled during bouts of inactivity.

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned to put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Reportedly the bulk of engine wear occurs at start-up, particular in colder temperatures.  Any thoughts?

John Breda

[M20F-1968]

On 10/1/2018 at 10:20 PM, aviatoreb said:

It’s a shame these engines don’t have some simply oil spritzer device already built into it whereby a little bit of oil could be drawn up from the case and spritz over the top to drip back down slowlybon it’s own.  Maybe by pressing a button (like the manual rubber prime button on my gas powered tug) or even electronically controlled so it can be done by timer so that it can be timed to keep the engine well oiled during bouts of inactivity.

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned to put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Reportedly the bulk of engine wear occurs at start-up, particular in colder temperatures.  Any thoughts?

John Breda

[M20F-1968]

On 10/1/2018 at 10:20 PM, aviatoreb said:

It’s a shame these engines don’t have some simply oil spritzer device already built into it whereby a little bit of oil could be drawn up from the case and spritz over the top to drip back down slowlybon it’s own.  Maybe by pressing a button (like the manual rubber prime button on my gas powered tug) or even electronically controlled so it can be done by timer so that it can be timed to keep the engine well oiled during bouts of inactivity.

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned to put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Reportedly the bulk of engine wear occurs at start-up, particular in colder temperatures.  Any thoughts?

John Breda

[M20F-1968]

Sorry, though it did not post.

[aviatoreb]

28 minutes ago, M20F-1968 said:

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned to put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Reportedly the bulk of engine wear occurs at start-up, particular in colder temperatures.  Any thoughts?

John Breda

Seems like a good idea - but I say that absent data.

They say there is massive wear on those occasions you start an engine after its been sitting some time since briefly there is no oil on the surfaces so there is scuffing.  If you run it say once a week there is still a thin layer of oil.

Also once its been sitting for some time, say more than two weeks (making up numbers) so much oil has worn off dripping down, that the metal is no longer protected so it is more likely to corrode.  

So for both purposes a pre-oiler seems like a good idea.  Both for pre-starting but also say for pre-oiling periodically say every week to keep oil covering everything.  I would think for good pre-oiling esp in the winter you would want to also pre-heat. (whether or not you would then be starting the engine following a pre-oiling).

Heck - Ill play through - what is the part you are talking about that has the STC?

[Andy95W]

2 hours ago, bradp said:

Doc - have you experienced the prop kicking around during the compression test? 

It'll do that if you let go of the prop.  I've seen someone get hit by the prop during a compression test, but only because he didn't realize the air was still connected.

[Guest]

3 hours ago, bradp said:

Doc - have you experienced the prop kicking around during the compression test? 

Yes, I was hit in the arm with a prop while working with an apprentice.  He had the air valve and I had the prop, well not quite!  Since then I prefer to have control of both.

Clarence

[Guest]

2 hours ago, aviatoreb said:

Seems like a good idea - but I say that absent data.

They say there is massive wear on those occasions you start an engine after its been sitting some time since briefly there is no oil on the surfaces so there is scuffing.  If you run it say once a week there is still a thin layer of oil.

Also once its been sitting for some time, say more than two weeks (making up numbers) so much oil has worn off dripping down, that the metal is no longer protected so it is more likely to corrode.  

So for both purposes a pre-oiler seems like a good idea.  Both for pre-starting but also say for pre-oiling periodically say every week to keep oil covering everything.  I would think for good pre-oiling esp in the winter you would want to also pre-heat. (whether or not you would then be starting the engine following a pre-oiling).

Heck - Ill play through - what is the part you are talking about that has the STC?

I would bet that there is just as much wear and damage done by pilots who don’t understand why their engine won’t start and crank on merrily hoping that it will start.

We had a charter pilot who couldn’t start a 421, so when the battery died he called for a GPU.  He cranked until there were no teeth left in the starter pinion gear.  Nothing $50K couldn’t fix.

Clarence

[jetdriven]

3 hours ago, M20F-1968 said:

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned to put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Reportedly the bulk of engine wear occurs at start-up, particular in colder temperatures.  Any thoughts?

John Breda

The pre-oiler is theoretically a great idea, but it uses oil pre-charged in an accumulator to provide the pre-oil for the next start. This introduces a few more hoses, a valve, and an accumulator, all which share the hot inside of a cramped Mooney cowl. I read, on here I think, of one that sprung an oil leak and caused problems.

[Mooneymite]

In theory, a pre-oiler makes sense, but I would be interested in knowing the actual benefit.  If most engines make it to TBO without an oil issue is it worth the cost/complexity/weight?

[ValkyrieRider]

My C was previously owned by an MSC mechanic.  He had a pre-oiler installed, and from my understanding, used it regularly.  I use it now because the concept makes sense to me, but of course, I don't have data to back up my assumptions.  The extra weight is minimal compared to the advertised benefit of protecting the engine, especially during the critical start-up.  I have read many different articles, both aviation and non-aviation, that seem to support the pre-oiler as a protectant for the engine, but some also say it isn't necessary.    

[AH-1 Cobra Pilot]

2 hours ago, ValkyrieRider said:

My C was previously owned by an MSC mechanic.  He had a pre-oiler installed, and from my understanding, used it regularly.  I use it now because the concept makes sense to me, but of course, I don't have data to back up my assumptions.  The extra weight is minimal compared to the advertised benefit of protecting the engine, especially during the critical start-up.  I have read many different articles, both aviation and non-aviation, that seem to support the pre-oiler as a protectant for the engine, but some also say it isn't necessary.    

Tell us more.  How many hours on your engine?  Compressions?  etc.

[201er]

Here's the final video. A 360 view of the Saturday formation demo flight over Panama City Beach:

 

[carusoam]

Amazing piece of artwork, Mike!

Nice job,

-a-

[Cyril Gibb]

On 10/7/2018 at 12:01 PM, M20F-1968 said:

There is such a device - it is a pre-oiler.  It is available by STC.  I have one, originally planned tpo put it on the airplane but then chose not to as a weight saving measure.  I spoke with Dugosh back in the day when I was doing my rebuild and they though it was not necessary.  I still have the pre-oiler and all of the paperwork should I want to install it.  The manufacturer of the pre-oiler states that it absolutely decreases wear.  Any thoughts?

John Breda

My understanding...

The area of concern in our engines for starting are the cam lobes and lifters.  The cam is "splash lubricated" by the crankshaft thrashing around.  Unlike an automotive engine, the cam is not drilled to allow oil to be spread onto the contact surfaces from the pressurised oil gallery.  Unless you have the cam drilled (STC) or ney nozzles installed (by STC), pre-oiling does nothing.

I've wondered why the engine manufacturers don't just drill a hole on the backside of each lobe like the centrilube stc does....