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endspeed(at)yahoo.com
Guest

Posted: Fri Aug 04, 2006 8:56 am Post subject: Alternator seizure engine failure

Hi Brian,  I have meant to throw cudos your way on the

predicted bearing failure/seizure's catastrophic

effect on an engine.  I thought this was a very remote

failure possibility when you postulated about it. 

Then, sure enough it goes and happens to one of our

posters.  Good forethought on your part.  Bob

Sultzbach



__________________________________________________

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Aug 04, 2006 12:48 pm Post subject: Alternator seizure engine failure

On Aug 4, 2006, at 12:52 PM, Robert Sultzbach wrote:



 	  Quote: 	
		   

 <endspeed(at)yahoo.com>



 Hi Brian,  I have meant to throw cudos your way on the

 predicted bearing failure/seizure's catastrophic

 effect on an engine.  I thought this was a very remote

 failure possibility when you postulated about it.

 Then, sure enough it goes and happens to one of our

 posters.  Good forethought on your part.  Bob

 Sultzbach


	


Thanks. I certainly didn't want to be proved right in the way that it  

happened.



On to the details, you probably want a belt that will fail and allow  

the engine to keep running rather than kill the engine.



A 50A 14V alternator is producing 700W at full output. If the  

alternator is 90% efficient it needs 770W of mechanical input. One HP  

is 760W. So you need a belt that will handle 1HP. That is not a very  

big belt. You sure don't need dual belts. If the alternator seizes  

the smaller belt will fail and your engine keeps running to carry you  

to a safe landing.



Now someone who knows belts should jump in here with belt sizing  

information to cover the transmission of 1HP.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

paulm(at)olypen.com
Guest

Posted: Fri Aug 04, 2006 2:45 pm Post subject: Alternator seizure engine failure

First 90% efficiency (for a 1970 alternator design) is in your dreams, try 

in the mid 70's but the main point is with "V" belts the belt tension needs 

to be high with an engine rpm of 6,000 and a single "V" based on the design 

of belts available 15-20 years ago. The subject engine is an EA81 that needs 

a light belt tension to prevent water pump bearing failure from too high but 

common belt tension. The tension must be high enough so there is no slippage 

under any expected load condition. Also remember the water pump is part of 

the belt load and finally you must consider the pulley to belt contact arc 

to transmit the load from the crank to the pump and alternator in a 3 pulley 

setup.



Thus the manufacturer of the conversion decided on dual belts with light 

tension as friction did the rest. This was to prevent a common failure at 

the time of water pump bearing wear and loss of coolant.



Its not easy to design a "V" belt that will slip on the one hand and not 

require high belt tension for its friction drive. Also consider in this 

application the crank to alternator pulley ratio is around 1-1.4 . Further 

throttled back it does not take much and with a "Sprague" clutch driving the 

prop (no inertial help here) and a very light flywheel there is little 

inertia to help. The specific belts are narrow with machined sides not the 

cloth covered ones of the era. There is no way the belt will snap if its in 

good condition until its been heated and burned thru. Again there was no 

chance of this here as the engine stopped immediately.



In addition there are around 700+ such dual belt conversions with over 

100,000 flight hours (some with over 4,000 hours) and this is the first 

known failure of its type. Hardly a bad design based on actual performance.



I have the specific dual belt system on my own engine so I do know the 

actual situation.



Good luck in finding a belt that acts like a fuse and instantly self 

destructs at 200% of design load but lasts 1,000 hours at 100% of design 

load.



The very common cogged timing belt widely used in modern auto engines can 

fail and if it does the engine stops. If the idler fails the belt slips the 

cogs and the engine fails. On an aircraft engine if an accessory case driven 

unit fails and locks up the engine likely will fail fast from major metal 

parts internal to the accessory case.



I believe the "result of the failure" is being addressed by your comment and 

you are missing the "real likely cause" which is a bad bearing from the use 

of a rebuilt alternator. 80 hours was the total time on the engine and also 

the alternator since rebuild where is not common to replace the bearings.



Paul

---

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Fri Aug 04, 2006 4:28 pm Post subject: Alternator seizure engine failure

Paul Messinger wrote:

 	  Quote: 	
		   

 <paulm(at)olypen.com>

 

 First 90% efficiency (for a 1970 alternator design) is in your dreams,

 try in the mid 70's but the main point is with "V" belts the belt

 tension needs to be high with an engine rpm of 6,000 and a single "V"

 based on the design of belts available 15-20 years ago. The subject

 engine is an EA81 that needs a light belt tension to prevent water pump

 bearing failure from too high but common belt tension. The tension must

 be high enough so there is no slippage under any expected load

 condition. Also remember the water pump is part of the belt load and

 finally you must consider the pulley to belt contact arc to transmit the

 load from the crank to the pump and alternator in a 3 pulley setup.


	


Well I was thinking in terms of a Lycoming engine wherein the belt

drives the alternator and only the alternator.



But, I am glad you chimed in here because, frankly, I don't know squat

about belt drives beyond the obvious and would not pretend otherwise.



-- 

Brian Lloyd                         361 Catterline Way

brian-yak at lloyd dot com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

- Antoine de Saint-Exupery

N6030X(at)DaveMorris.com
Guest

Posted: Fri Aug 04, 2006 4:42 pm Post subject: Alternator seizure engine failure

Sounds like a more reliable approach for vehicles 

that can't "pull over to the side of the road" in 

case of failure would be to mount 2 alternators 

with 1/2 the current capacity each, driven by 2 

separate belts neither of which require the kind 

of tension that would seize the engine or burn out the bearings.



Dave Morris

At 05:36 PM 8/4/2006, you wrote:

[quote]



First 90% efficiency (for a 1970 alternator 

design) is in your dreams, try in the mid 70's 

but the main point is with "V" belts the belt 

tension needs to be high with an engine rpm of 

6,000 and a single "V" based on the design of 

belts available 15-20 years ago. The subject 

engine is an EA81 that needs a light belt 

tension to prevent water pump bearing failure 

from too high but common belt tension. The 

tension must be high enough so there is no 

slippage under any expected load condition. Also 

remember the water pump is part of the belt load 

and finally you must consider the pulley to belt 

contact arc to transmit the load from the crank 

to the pump and alternator in a 3 pulley setup.



Thus the manufacturer of the conversion decided 

on dual belts with light tension as friction did 

the rest. This was to prevent a common failure 

at the time of water pump bearing wear and loss of coolant.



Its not easy to design a "V" belt that will slip 

on the one hand and not require high belt 

tension for its friction drive. Also consider in 

this application the crank to alternator pulley 

ratio is around 1-1.4 . Further throttled back 

it does not take much and with a "Sprague" 

clutch driving the prop (no inertial help here) 

and a very light flywheel there is little 

inertia to help. The specific belts are narrow 

with machined sides not the cloth covered ones 

of the era. There is no way the belt will snap 

if its in good condition until its been heated 

and burned thru. Again there was no chance of 

this here as the engine stopped immediately.



In addition there are around 700+ such dual belt 

conversions with over 100,000 flight hours (some 

with over 4,000 hours) and this is the first 

known failure of its type. Hardly a bad design based on actual performance.



I have the specific dual belt system on my own 

engine so I do know the actual situation.



Good luck in finding a belt that acts like a 

fuse and instantly self destructs at 200% of 

design load but lasts 1,000 hours at 100% of design load.



The very common cogged timing belt widely used 

in modern auto engines can fail and if it does 

the engine stops. If the idler fails the belt 

slips the cogs and the engine fails. On an 

aircraft engine if an accessory case driven unit 

fails and locks up the engine likely will fail 

fast from major metal parts internal to the accessory case.



I believe the "result of the failure" is being 

addressed by your comment and you are missing 

the "real likely cause" which is a bad bearing 

from the use of a rebuilt alternator. 80 hours 

was the total time on the engine and also the 

alternator since rebuild where is not common to replace the bearings.



Paul

---

chaztuna(at)adelphia.net
Guest

Posted: Fri Aug 04, 2006 6:53 pm Post subject: Alternator seizure engine failure

Dave,

  This is one of those, "it looked good on paper" ideas. The reality is that if both alternators are driven off the front of the engine, losing the belt on one, generally takes out the other alternator. When a belt fails, it often gets tangled up in any near by pulleys and belts. This will derail or destroy the belt for the second alternator.

  Bob N's recommendation of a rear drive (Lycoming engine) secondary alternator (like the B&C units) is a safer bet.

 Charlie Kuss



 

 [quote]--> AeroElectric-List message posted by: Dave N6030X <N6030X(at)DaveMorris.com>



 Sounds like a more reliable approach for vehicles that can't "pull over to the side of the road" in case of failure would be to mount 2 alternators with 1/2 the current capacity each, driven by 2 separate belts neither of which require the kind of tension that would seize the engine or burn out the bearings.



 Dave Morris



 

 At 05:36 PM 8/4/2006, you wrote:

 [quote]--> AeroElectric-List message posted by: "Paul Messinger" <paulm(at)olypen.com>



 First 90% efficiency (for a 1970 alternator design) is in your dreams, try in the mid 70's but the main point is with "V" belts the belt tension needs to be high with an engine rpm of 6,000 and a single "V" based on the design of belts available 15-20 years ago. The subject engine is an EA81 that needs a light belt tension to prevent water pump bearing failure from too high but common belt tension. The tension must be high enough so there is no slippage under any expected load condition. Also remember the water pump is part of the belt load and finally you must consider the pulley to belt contact arc to transmit the load from the crank to the pump and alternator in a 3 pulley setup.



 Thus the manufacturer of the conversion decided on dual belts with light tension as friction did the rest. This was to prevent a common failure at the time of water pump bearing wear and loss of coolant.



 Its not easy to design a "V" belt that will slip on the one hand and not require high belt tension for its friction drive. Also consider in this application the crank to alternator pulley ratio is around 1-1.4 . Further throttled back it does not take much and with a "Sprague" clutch driving the prop (no inertial help here) and a very light flywheel there is little inertia to help. The specific belts are narrow with machined sides not the cloth covered ones of the era. There is no way the belt will snap if its in good condition until its been heated and burned thru. Again there was no chance of this here as the engine stopped immediately.



 In addition there are around 700+ such dual belt conversions with over 100,000 flight hours (some with over 4,000 hours) and this is the first known failure of its type. Hardly a bad design based on actual performance.



 I have the specific dual belt system on my own engine so I do know the actual situation.



 Good luck in finding a belt that acts like a fuse and instantly self destructs at 200% of design load but lasts 1,000 hours at 100% of design load.



 The very common cogged timing belt widely used in modern auto engines can fail and if it does the engine stops. If the idler fails the belt slips the cogs and the engine fails. On an aircraft engine if an accessory case driven unit fails and locks up the engine likely will fail fast from major metal parts internal to the accessory case.



 I believe the "result of the failure" is being addressed by your comment and you are missing the "real likely cause" which is a bad bearing from the use of a rebuilt alternator. 80 hours was the total time on the engine and also the alternator since rebuild where is not common to replace the bearings.



 Paul



 

 ---

N6030X(at)DaveMorris.com
Guest

Posted: Fri Aug 04, 2006 7:22 pm Post subject: Alternator seizure engine failure

So, what happens in the case of a gear-driven 

alternator when it seizes up?  Does it shred the 

whole back end of the Lycoming?



Dave



At 09:45 PM 8/4/2006, you wrote:

[quote]Dave,

  This is one of those, "it looked good on 

 paper" ideas. The reality is that if both 

 alternators are driven off the front of the 

 engine, losing the belt on one, generally takes 

 out the other alternator. When a belt fails, it 

 often gets tangled up in any near by pulleys 

 and belts. This will derail or destroy the belt for the second alternator.

  Bob N's recommendation of a rear drive 

 (Lycoming engine) secondary alternator (like the B&C units) is a safer bet.

Charlie Kuss

>

>

>Sounds like a more reliable approach for 

>vehicles that can't "pull over to the side of 

>the road" in case of failure would be to mount 

>2 alternators with 1/2 the current capacity 

>each, driven by 2 separate belts neither of 

>which require the kind of tension that would 

>seize the engine or burn out the bearings.

>

>Dave Morris

>At 05:36 PM 8/4/2006, you wrote:

>>

>>

>>First 90% efficiency (for a 1970 alternator 

>>design) is in your dreams, try in the mid 70's 

>>but the main point is with "V" belts the belt 

>>tension needs to be high with an engine rpm of 

>>6,000 and a single "V" based on the design of 

>>belts available 15-20 years ago. The subject 

>>engine is an EA81 that needs a light belt 

>>tension to prevent water pump bearing failure 

>>from too high but common belt tension. The 

>>tension must be high enough so there is no 

>>slippage under any expected load condition. 

>>Also remember the water pump is part of the 

>>belt load and finally you must consider the 

>>pulley to belt contact arc to transmit the 

>>load from the crank to the pump and alternator in a 3 pulley setup.

>>

>>Thus the manufacturer of the conversion 

>>decided on dual belts with light tension as 

>>friction did the rest. This was to prevent a 

>>common failure at the time of water pump bearing wear and loss of coolant.

>>

>>Its not easy to design a "V" belt that will 

>>slip on the one hand and not require high belt 

>>tension for its friction drive. Also consider 

>>in this application the crank to alternator 

>>pulley ratio is around 1-1.4 . Further 

>>throttled back it does not take much and with 

>>a "Sprague" clutch driving the prop (no 

>>inertial help here) and a very light flywheel 

>>there is little inertia to help. The specific 

>>belts are narrow with machined sides not the 

>>cloth covered ones of the era. There is no way 

>>the belt will snap if its in good condition 

>>until its been heated and burned thru. Again 

>>there was no chance of this here as the engine stopped immediately.

>>

>>In addition there are around 700+ such dual 

>>belt conversions with over 100,000 flight 

>>hours (some with over 4,000 hours) and this is 

>>the first known failure of its type. Hardly a 

>>bad design based on actual performance.

>>

>>I have the specific dual belt system on my own 

>>engine so I do know the actual situation.

>>

>>Good luck in finding a belt that acts like a 

>>fuse and instantly self destructs at 200% of 

>>design load but lasts 1,000 hours at 100% of design load.

>>

>>The very common cogged timing belt widely used 

>>in modern auto engines can fail and if it does 

>>the engine stops. If the idler fails the belt 

>>slips the cogs and the engine fails. On an 

>>aircraft engine if an accessory case driven 

>>unit fails and locks up the engine likely will 

>>fail fast from major metal parts internal to the accessory case.

>>

>>I believe the "result of the failure" is being 

>>addressed by your comment and you are missing 

>>the "real likely cause" which is a bad bearing 

>>from the use of a rebuilt alternator. 80 hours 

>>was the total time on the engine and also the 

>>alternator since rebuild where is not common to replace the bearings.

>>

>>Paul

>>

>>

>>---

oldbob(at)BeechOwners.com
Guest

Posted: Fri Aug 04, 2006 7:42 pm Post subject: Alternator seizure engine failure

Good Evening Dave,



I do not remember for sure, but I think B&C uses a

shear coupling on their alternator that is designed to

be driven off of an accessory pad on the Lycoming

which otherwise generally drives a vacuum pump.



Anyone know for sure?



Happy Skies,



Old Bob



--- Dave N6030X <N6030X(at)DaveMorris.com> wrote:



[quote] 

 <N6030X(at)DaveMorris.com>

 

 So, what happens in the case of a gear-driven 

 alternator when it seizes up?  Does it shred the 

 whole back end of the Lycoming?

 

 Dave

 

 At 09:45 PM 8/4/2006, you wrote:

 >Dave,

 >  This is one of those, "it looked good on 

 > paper" ideas. The reality is that if both 

 > alternators are driven off the front of the 

 > engine, losing the belt on one, generally takes 

 > out the other alternator. When a belt fails, it 

 > often gets tangled up in any near by pulleys 

 > and belts. This will derail or destroy the belt

 for the second alternator.

 >  Bob N's recommendation of a rear drive 

 > (Lycoming engine) secondary alternator (like the

 B&C units) is a safer bet.

 >Charlie Kuss

 >

 >

 >>

 N6030X <N6030X(at)DaveMorris.com>

 >>

 >>Sounds like a more reliable approach for 

 >>vehicles that can't "pull over to the side of 

 >>the road" in case of failure would be to mount 

 >>2 alternators with 1/2 the current capacity 

 >>each, driven by 2 separate belts neither of 

 >>which require the kind of tension that would 

 >>seize the engine or burn out the bearings.

 >>

 >>Dave Morris

 >>

 >>

 >>At 05:36 PM 8/4/2006, you wrote:

 >>>

 Messinger" <paulm(at)olypen.com>

 >>>

 >>>First 90% efficiency (for a 1970 alternator 

 >>>design) is in your dreams, try in the mid 70's 

 >>>but the main point is with "V" belts the belt 

 >>>tension needs to be high with an engine rpm of 

 >>>6,000 and a single "V" based on the design of 

 >>>belts available 15-20 years ago. The subject 

 >>>engine is an EA81 that needs a light belt 

 >>>tension to prevent water pump bearing failure 

 >>>from too high but common belt tension. The 

 >>>tension must be high enough so there is no 

 >>>slippage under any expected load condition. 

 >>>Also remember the water pump is part of the 

 >>>belt load and finally you must consider the 

 >>>pulley to belt contact arc to transmit the 

 >>>load from the crank to the pump and alternator in

 a 3 pulley setup.

 >>>

 >>>Thus the manufacturer of the conversion 

 >>>decided on dual belts with light tension as 

 >>>friction did the rest. This was to prevent a 

 >>>common failure at the time of water pump bearing

 wear and loss of coolant.

 >>>

 >>>Its not easy to design a "V" belt that will 

 >>>slip on the one hand and not require high belt 

 >>>tension for its friction drive. Also consider 

 >>>in this application the crank to alternator 

 >>>pulley ratio is around 1-1.4 . Further 

 >>>throttled back it does not take much and with 

 >>>a "Sprague" clutch driving the prop (no 

 >>>inertial help here) and a very light flywheel 

 >>>there is little inertia to help. The specific 

 >>>belts are narrow with machined sides not the 

 >>>cloth covered ones of the era. There is no way 

 >>>the belt will snap if its in good condition 

 >>>until its been heated and burned thru. Again 

 >>>there was no chance of this here as the engine

 stopped immediately.

 >>>

 >>>In addition there are around 700+ such dual 

 >>>belt conversions with over 100,000 flight 

 >>>hours (some with over 4,000 hours) and this is 

 >>>the first known failure of its type. Hardly a 

 >>>bad design based on actual performance.

 >>>

 >>>I have the specific dual belt system on my own 

 >>>engine so I do know the actual situation.

 >>>

 >>>Good luck in finding a belt that acts like a 

 >>>fuse and instantly self destructs at 200% of 

 >>>design load but lasts 1,000 hours at 100% of

 design load.

 >>>

 >>>The very common cogged timing belt widely used 

 >>>in modern auto engines can fail and if it does 

 >>>the engine stops. If the idler fails the belt 

 >>>slips the cogs and the engine fails. On an 

 >>>aircraft engine if an accessory case driven 

 >>>unit fails and locks up the engine likely will 

 >>>fail fast from major metal parts internal to the

 accessory case.

 >>>

 >>>I believe the "result of the failure" is being 

 >>>addressed by your comment and you are missing 

 >>>the "real likely cause" which is a bad bearing 

 >>>from the use of a rebuilt alternator. 80 hours 

 >>>was the total time on the engine and also the 

 >>>alternator since rebuild where is not common to

 replace the bearings.

 >>>

 >>>Paul

 >>>

 >>>

 >>>---

oldbob(at)BeechOwners.com
Guest

Posted: Fri Aug 04, 2006 7:48 pm Post subject: Alternator seizure engine failure

Good Evening Once Again Dave,



Just checked and the B&C does include a shear drive

unit.



Happy Skies,



Old Bob



--- Dave N6030X <N6030X(at)DaveMorris.com> wrote:



[quote] 

 <N6030X(at)DaveMorris.com>

 

 So, what happens in the case of a gear-driven 

 alternator when it seizes up?  Does it shred the 

 whole back end of the Lycoming?

 

 Dave

 

 At 09:45 PM 8/4/2006, you wrote:

 >Dave,

 >  This is one of those, "it looked good on 

 > paper" ideas. The reality is that if both 

 > alternators are driven off the front of the 

 > engine, losing the belt on one, generally takes 

 > out the other alternator. When a belt fails, it 

 > often gets tangled up in any near by pulleys 

 > and belts. This will derail or destroy the belt

 for the second alternator.

 >  Bob N's recommendation of a rear drive 

 > (Lycoming engine) secondary alternator (like the

 B&C units) is a safer bet.

 >Charlie Kuss

 >

 >

 >>

 N6030X <N6030X(at)DaveMorris.com>

 >>

 >>Sounds like a more reliable approach for 

 >>vehicles that can't "pull over to the side of 

 >>the road" in case of failure would be to mount 

 >>2 alternators with 1/2 the current capacity 

 >>each, driven by 2 separate belts neither of 

 >>which require the kind of tension that would 

 >>seize the engine or burn out the bearings.

 >>

 >>Dave Morris

 >>

 >>

 >>At 05:36 PM 8/4/2006, you wrote:

 >>>

 Messinger" <paulm(at)olypen.com>

 >>>

 >>>First 90% efficiency (for a 1970 alternator 

 >>>design) is in your dreams, try in the mid 70's 

 >>>but the main point is with "V" belts the belt 

 >>>tension needs to be high with an engine rpm of 

 >>>6,000 and a single "V" based on the design of 

 >>>belts available 15-20 years ago. The subject 

 >>>engine is an EA81 that needs a light belt 

 >>>tension to prevent water pump bearing failure 

 >>>from too high but common belt tension. The 

 >>>tension must be high enough so there is no 

 >>>slippage under any expected load condition. 

 >>>Also remember the water pump is part of the 

 >>>belt load and finally you must consider the 

 >>>pulley to belt contact arc to transmit the 

 >>>load from the crank to the pump and alternator in

 a 3 pulley setup.

 >>>

 >>>Thus the manufacturer of the conversion 

 >>>decided on dual belts with light tension as 

 >>>friction did the rest. This was to prevent a 

 >>>common failure at the time of water pump bearing

 wear and loss of coolant.

 >>>

 >>>Its not easy to design a "V" belt that will 

 >>>slip on the one hand and not require high belt 

 >>>tension for its friction drive. Also consider 

 >>>in this application the crank to alternator 

 >>>pulley ratio is around 1-1.4 . Further 

 >>>throttled back it does not take much and with 

 >>>a "Sprague" clutch driving the prop (no 

 >>>inertial help here) and a very light flywheel 

 >>>there is little inertia to help. The specific 

 >>>belts are narrow with machined sides not the 

 >>>cloth covered ones of the era. There is no way 

 >>>the belt will snap if its in good condition 

 >>>until its been heated and burned thru. Again 

 >>>there was no chance of this here as the engine

 stopped immediately.

 >>>

 >>>In addition there are around 700+ such dual 

 >>>belt conversions with over 100,000 flight 

 >>>hours (some with over 4,000 hours) and this is 

 >>>the first known failure of its type. Hardly a 

 >>>bad design based on actual performance.

 >>>

 >>>I have the specific dual belt system on my own 

 >>>engine so I do know the actual situation.

 >>>

 >>>Good luck in finding a belt that acts like a 

 >>>fuse and instantly self destructs at 200% of 

 >>>design load but lasts 1,000 hours at 100% of

 design load.

 >>>

 >>>The very common cogged timing belt widely used 

 >>>in modern auto engines can fail and if it does 

 >>>the engine stops. If the idler fails the belt 

 >>>slips the cogs and the engine fails. On an 

 >>>aircraft engine if an accessory case driven 

 >>>unit fails and locks up the engine likely will 

 >>>fail fast from major metal parts internal to the

 accessory case.

 >>>

 >>>I believe the "result of the failure" is being 

 >>>addressed by your comment and you are missing 

 >>>the "real likely cause" which is a bad bearing 

 >>>from the use of a rebuilt alternator. 80 hours 

 >>>was the total time on the engine and also the 

 >>>alternator since rebuild where is not common to

 replace the bearings.

 >>>

 >>>Paul

 >>>

 >>>

 >>>---

paulm(at)olypen.com
Guest

Posted: Fri Aug 04, 2006 7:55 pm Post subject: Alternator seizure engine failure

I agree that a LYC belt drive is a different issue and not likely to be a 

problem with a frozen bearing.



My point is the specific subject auto engine conversion is very different. 

Lots of trades to consider and no perfect solution.



But as you pointed out some time ago bearing failure in a locked failure 

mode can happen however rare it might be.



I might point out the Subaru engine has demonstrated the ability to run for 

as long as 30 min with No coolant so if the engine can be kept running its 

possible to land safely. The key is using the prop inertia of a non clutch 

drive and / or a reasonable sized flywheel to force the belt to start 

slipping. In this case the manufacturer chose to assume the bearing lock up 

was less likely than a belt failure and or the pump leaking from belt side 

load.



Since the original design the use of dual belts has been questionable in 

auto engine conversions including the belt reduction designs. Stratus for 

example has had several dual belt failures where one belt failed and then 

took out the other belt and went to a single wider belt.  Eggenfelner 

recently had a multi belt reduction unit fail all the belts from a single 

FOD starting with a single belt that progressed to the rest of the belts and 

dropped the design.



Perhaps a single belt under slightly more tension is a better way to go and 

risk water pump leakage on this specific application. I have considered this 

and am considering a single belt as its simple to do and pump shaft leakage 

is a slow failure and thus simple to detect the loss of coolant before its a 

serious risk to the engine. In any event its better than a locked engine and 

becoming a glider where I live. Lets see; 95% of the time its a stump farm, 

high trees, rough mountain sides, or cold seas for landing sites.



The trades in an auto engine conversion are many. Here the Sprague clutch 

allowed a saving of 20 pounds of flywheel to reduce the torsional loads from 

a 4 cyl engine. Much the same as the flywheel on Lyc vs no flywheel on the 

Cont where the torsionals are different due to basic engine design. Or the 

Cont trade of accessory gear drive for the alternator vs the Lyc belt drive. 

Different solutions from different designers.



No criticism of your comments just a clarification of the exact 

configuration of the failure and its effects. I would not expect that 99% of 

this list members know the specific design of the subject system.



Just as we would not consider using a used crank with out magniflux etc, we 

should not use a repaired alternator without new HI quality bearings.



Paul



---

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Sat Aug 05, 2006 5:29 am Post subject: Alternator seizure engine failure

On Aug 4, 2006, at 11:40 PM, OldBob Siegfried wrote:



 	  Quote: 	
		   

 <oldbob(at)beechowners.com>



 Good Evening Dave,



 I do not remember for sure, but I think B&C uses a

 shear coupling on their alternator that is designed to

 be driven off of an accessory pad on the Lycoming

 which otherwise generally drives a vacuum pump.



 Anyone know for sure?


	


Yes, they do.



In fact, I have just heard of my first B&C alternator failure because  

the shear coupling failed. (It happened on a friend's CJ6A.) Seems  

B&C is now using a slightly stronger shear coupling and is providing  

a retrofit for older units.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

chaztuna(at)adelphia.net
Guest

Posted: Sat Aug 05, 2006 5:36 am Post subject: Alternator seizure engine failure

Paul,

  I agree that use of known, high quality parts is the smart thing to do.  I have some knowledge of the Subaru engine (professional auto mechanic) but don't claim to be a Subaru expert. Have you considered installation of an "outboard" support bearing (with related shaft) to aid in support of the water pump?

  If the water pump pulley was originally fitted with a cooling fan (probably not) a stub axle could be attached to this surface to support an outboard bearing. Failing that, a custom pulley could be machined to facilitate an outboard support bearing.

 Charlie Kuss



  	  Quote: 	
		  --> AeroElectric-List message posted by: "Paul Messinger" <paulm(at)olypen.com>



 I agree that a LYC belt drive is a different issue and not likely to be a problem with a frozen bearing.



 My point is the specific subject auto engine conversion is very different. Lots of trades to consider and no perfect solution.



 But as you pointed out some time ago bearing failure in a locked failure mode can happen however rare it might be.



 I might point out the Subaru engine has demonstrated the ability to run for as long as 30 min with No coolant so if the engine can be kept running its possible to land safely. The key is using the prop inertia of a non clutch drive and / or a reasonable sized flywheel to force the belt to start slipping. In this case the manufacturer chose to assume the bearing lock up was less likely than a belt failure and or the pump leaking from belt side load.



 Since the original design the use of dual belts has been questionable in auto engine conversions including the belt reduction designs. Stratus for example has had several dual belt failures where one belt failed and then took out the other belt and went to a single wider belt.  Eggenfelner recently had a multi belt reduction unit fail all the belts from a single FOD starting with a single belt that progressed to the rest of the belts and dropped the design.

 

 Perhaps a single belt under slightly more tension is a better way to go and risk water pump leakage on this specific application. I have considered this and am considering a single belt as its simple to do and pump shaft leakage is a slow failure and thus simple to detect the loss of coolant before its a serious risk to the engine. In any event its better than a locked engine and becoming a glider where I live. Lets see; 95% of the time its a stump farm, high trees, rough mountain sides, or cold seas for landing sites.



 The trades in an auto engine conversion are many. Here the Sprague clutch allowed a saving of 20 pounds of flywheel to reduce the torsional loads from a 4 cyl engine. Much the same as the flywheel on Lyc vs no flywheel on the Cont where the torsionals are different due to basic engine design. Or the Cont trade of accessory gear drive for the alternator vs the Lyc belt drive. Different solutions from different designers.



 No criticism of your comments just a clarification of the exact configuration of the failure and its effects. I would not expect that 99% of this list members know the specific design of the subject system.



 Just as we would not consider using a used crank with out magniflux etc, we should not use a repaired alternator without new HI quality bearings.



 Paul 	
snipped

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Sat Aug 05, 2006 5:36 am Post subject: Alternator seizure engine failure

On Aug 4, 2006, at 11:54 PM, Paul Messinger wrote:



 	  Quote: 	
		   No criticism of your comments just a clarification of the exact  

 configuration of the failure and its effects. I would not expect  

 that 99% of this list members know the specific design of the  

 subject system.


	


No problem and no criticism perceived on this end. I know a fair bit  

about a fair bit and do have a tendency to "think out loud" but I do  

try to avoid what my ex-wife used to call "male answer  

syndrome" (MAS), i.e. the need to come up with an answer even if you  

haven't got one. I find that the phrase, "I don't know but I will  

find out," works pretty well, especially with children.



(BTW, after meeting some women with MAS I changed the acronym to be  

"must-answer syndrome.")



 	  Quote: 	
		  

 Just as we would not consider using a used crank with out magniflux  

 etc, we should not use a repaired alternator without new HI quality  

 bearings.


	


Makes sense to me.



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

N6030X(at)DaveMorris.com
Guest

Posted: Sat Aug 05, 2006 6:14 am Post subject: Alternator seizure engine failure

LOL!!!  That's great Brian!

It just hit me!



There are no women on aviation internet forums!!!



We're here to answer each other's questions, even if we don't have 

the answer!!!



(slapping head)

Wow.



Dave



At 08:34 AM 8/5/2006, you wrote:

 	  Quote: 	
		  

but I do

try to avoid what my ex-wife used to call "male answer

syndrome" (MAS), i.e. the need to come up with an answer even if you

haven't got one.

paulm(at)olypen.com
Guest

Posted: Sat Aug 05, 2006 8:27 am Post subject: Alternator seizure engine failure

The pulley is deep dished and the belt0 groove is actually slightly inside the span of the shaft bearings.

  

 The problem with outer third bearings0 is alignment. This is a major problem with reduction units that have a hard0 coupling to the crank and in theory an outer bearing helps the cog belt side0 load. In fact it usually promotes failure as the TIR of the outer support must0 be less than 0.0005" over all conditions or it will add to the crank bearing0 load.

  

 Frankly I believe there is no real0 concern with the water pump bearing failure but clearly some are worried. I have0 torn down over a dozen subaru engines and none had pump shaft wear that I could0 see. Brand new pumps are available and not expensive so its no big deal to start0 with new parts.

  

 I was only relating the stated reason0 (by the mfgr) for the dual belts as well as the idea of redundancy. The reason I0 chose to put the pulley set with dual belts is the changed pully ratios better0 suited to the higher average rpm of the auto conversion. The original concept of0 dual belts for redundancy has been demonstrated to be false as one belt failure0 usually takes out the other. Not unlike the light twin engined aircraft where0 one engine failure overstresses (in this case) the pilot and the aircraft0 crashes..

  

 Paul

  

    ---

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Sat Aug 05, 2006 10:32 am Post subject: Alternator seizure engine failure

On Aug 5, 2006, at 10:10 AM, Dave N6030X wrote:



 	  Quote: 	
		   

 <N6030X(at)DaveMorris.com>



 LOL!!!  That's great Brian!

 It just hit me!



 There are no women on aviation internet forums!!!


	


Well, there are a few and it is usually worth paying attention when  

they speak.



 	  Quote: 	
		  

 We're here to answer each other's questions, even if we don't have  

 the answer!!!



 (slapping head)

 Wow.


	


Yeah, it is funny but it is scary at the same time. There is another  

variation of MAS that is addressed by, "just because you can doesn't  

mean you should." 



Brian Lloyd                         361 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

chaztuna(at)adelphia.net
Guest

Posted: Sat Aug 05, 2006 10:53 am Post subject: Alternator seizure engine failure

Paul

 Is TIR engineer speak for "total included run out"?

Charlie Kuss



---- Paul Messinger <paulm(at)olypen.com> wrote: 

[quote] The pulley is deep dished and the belt groove is actually slightly inside 

 the span of the shaft bearings.

 

 The problem with outer third bearings is alignment. This is a major problem 

 with reduction units that have a hard coupling to the crank and in theory an 

 outer bearing helps the cog belt side load. In fact it usually promotes 

 failure as the TIR of the outer support must be less than 0.0005" over all 

 conditions or it will add to the crank bearing load.

 

 Frankly I believe there is no real concern with the water pump bearing 

 failure but clearly some are worried. I have torn down over a dozen subaru 

 engines and none had pump shaft wear that I could see. Brand new pumps are 

 available and not expensive so its no big deal to start with new parts.

 

 I was only relating the stated reason (by the mfgr) for the dual belts as 

 well as the idea of redundancy. The reason I chose to put the pulley set 

 with dual belts is the changed pully ratios better suited to the higher 

 average rpm of the auto conversion. The original concept of dual belts for 

 redundancy has been demonstrated to be false as one belt failure usually 

 takes out the other. Not unlike the light twin engined aircraft where one 

 engine failure overstresses (in this case) the pilot and the aircraft 

 crashes..

 

 Paul

 

   ---

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sat Aug 05, 2006 11:53 am Post subject: Alternator seizure engine failure

total indicator runout



Bob McC

---

_________________
Bob McC
Falco #908
(just starting)

gmcjetpilot(at)yahoo.com
Guest

Posted: Sat Aug 05, 2006 12:13 pm Post subject: Alternator seizure engine failure

This is semi related.

   

  I had a generator seize once on a light twin, PA-23-160 Apache.

  

It was a non event and smelled (burned rubber).

   

  Fortunitly it was on the ground. The engine started and 

I got a wiff of something burning. 

   

  Shut down, investigated and found a smoking belt. Too hot 

to touch, it was a very soft pathetic looking belt but still on.

   

  The V-belt pulleys on my Lyc flywheel pulley are deep as  

on that generator. The belt is so short I doubt it would come 

off a sized alt/gen. 

  

I suppose if the engine continues to run it could burn thru 

the belt or possibly start a fire worse case? My guess is 

it would just get hot, melt and make more slack and just 

rub and wear away. That is what happened to me. It was 

just running around the Gen pulley and was very loose.

    

  But who really knows all the possible senerios there are. 

On the Apache the metal cowl is wide open and the belt 

is cooled. In a homebuilt the belt is shielded from incoming 

air and covered in a flammable fiberglass cowl. 

   

  George

   



  Get on board. [url=http://us.rd.yahoo.com/evt=40791/*http://advision.webevents.yahoo.com/handraisers]You're invited[/url] to try the new Yahoo! Mail Beta.

paulm(at)olypen.com
Guest

Posted: Sat Aug 05, 2006 3:36 pm Post subject: Alternator seizure engine failure

Please do make general0 statements.

  

 My auto conversion has the alternator0 cooled by direct inlet air and its in a aluminum cowl. I will grant you some of0 the belt is semi shielded but not all.

  

 Paul

 [quote]   ---

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