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  #1  
Old 01-24-2017, 05:13 PM
RV7DES RV7DES is offline
 
Join Date: Feb 2012
Location: Auckland New Zealand
Posts: 35
Default Accusump Failure Immediate total Oil loss

I have just had my plane lose all its oil just before shutdown when the accusump blew its top. Has anyone had this issue? I lost almost all the oil in a few seconds. If it happened during flight I would be going down.

So far Canton has said maybe I shouldn't fit a valve direct to the accusump, and maybe the vibrations caused the top to seperate. However I am not impressed by the thickness of the unit around the tread, and believe it was an issue waiting to happen, and would not be happy fitting one again until I know why. I'd like to share this with as many others that have these units fitted. Until this failure I loved the system, and have done lots of aeros.

Im including my initial report to Canton and would welcome another thoughts. It was very fortunate this occurred 10sec before shutdown.

I'll include photos as soon as I can.

**************

Accusump top separating from body while engine running

Engine : IO-360 aircraft
Hours total 1200
Accusump fitted March 2013 with approximately 350hours flown
Electronic valve fitted Nov 2016 with approximately 20 hours flown since fitting

On 20th of Jan 2017 at around 10am I left Te Kowhai for a 30min flight to Tauranga.
While preflighting I switched the electronic oil valve to on position to pre oil the plane for around 2min. Shut the valve off and started the plane.

The flight was normal lasting around 30min reaching no higher than 3000ft before landing in Tauranga. A few minutes before landing pre landing checks indicated the engine running fine and oil pressure normal. Some 30m before shut down a loud bang occurred and I shut down the engine. The following fault was found.

The Accusump had separated at the top and almost all oil from the engine was lost.

If this had occurred at anytime during the flight the plane would have required an emergency landing with the possible loss of life. Other planes around the world are fitted with these units, and and there is a grave concerned that this could occur again.

During the whole flight the valve had been left off to allow maximum oil to flow throughout the engine. The accusump was installed for aerobatic flight and to insure the engine has oil when any negative g forces occur.

24-046 - ACCUSUMP 1QT NO VALVE

24-270X - ACCUSUMP PRO ELECTRIC VALVE KIT

All components were fitted by qualified aircraft engineers and according to manufactures instructions.

***********

On testing the value with air, we found the valve when closed (as I had it) is letting air through into where the accusump was but not letting it out. This would account for the total oil loss after the incident.
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  #2  
Old 01-24-2017, 05:40 PM
RV7DES RV7DES is offline
 
Join Date: Feb 2012
Location: Auckland New Zealand
Posts: 35
Default

http://imgur.com/a/M5DKR
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  #3  
Old 01-24-2017, 05:42 PM
RV7DES RV7DES is offline
 
Join Date: Feb 2012
Location: Auckland New Zealand
Posts: 35
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  #4  
Old 01-24-2017, 09:39 PM
Michael Henning Michael Henning is offline
 
Join Date: Jun 2011
Location: Nashua, NH
Posts: 546
Default

I'm glad you were on the ground and shutting the engine down. Now it is just a PITA. I have the Moroso 1.5 qt accumulator, about 165 hours and electric valve mounted on top. No issues so far, and haven't heard of any issues with any accumulators. I don't see how the valve being mounted on top would be a factor in the failure of the unit. That aluminum does seem really thin though.
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  #5  
Old 01-24-2017, 09:41 PM
PaigeHoffart PaigeHoffart is offline
 
Join Date: Jun 2005
Posts: 375
Default

Was the pressure relief valve functional?
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  #6  
Old 01-24-2017, 09:51 PM
F1R F1R is offline
 
Join Date: Nov 2010
Location: ____
Posts: 911
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Clearly the problem originated from the flames.
Glad you are down safe.

Last edited by F1R : 01-24-2017 at 09:54 PM.
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  #7  
Old 01-24-2017, 09:54 PM
Michael Henning Michael Henning is offline
 
Join Date: Jun 2011
Location: Nashua, NH
Posts: 546
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The accumulator should not exceed the oil pressure of the engine. My accumulator is showing 60 psi on the preflight, and I keep it open during short flights. Long flights I use it as a emergency oil source if I should start losing oil pressure.
The oil pressure seen in our engines should never be able to blow that apart the way that unit failed.
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RV-4 #2750
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  #8  
Old 01-25-2017, 02:14 AM
RV7DES RV7DES is offline
 
Join Date: Feb 2012
Location: Auckland New Zealand
Posts: 35
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Looking at data nothing out of the ordinary regarding oil pressure. Didn't have a release valve on the Accusump. When I close the valve and shut the engine down the accusump reads around 160psi on its meter. I've been told this is normal due to it being air pressure not oil. I can't see my engine producing that much pressure. Yes the thickness is an issue and I'm not confident this would not happen again if I selected the same brand. Until this happened I thought everything was fantastic. Accusump does give some real advantages. I had checked the system 10 hours after the valve was fitted with no evidence of fatigue.
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Last edited by RV7DES : 01-25-2017 at 02:42 AM.
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  #9  
Old 01-25-2017, 06:17 AM
Michael Henning Michael Henning is offline
 
Join Date: Jun 2011
Location: Nashua, NH
Posts: 546
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Pressure is pressure. If your engine oil pressure is 70, the accumulator pressure should be equal to that. On the Moroso accumulator, the unit is charged with 10 PSI of air as a precharge, but after that, it is the engine oil pressure that determines the accumulator pressure. I would check your engine monitor to see if you are getting unusually high oil pressure somewhere along the way.
There are a bunch of us using accumulators on this site, and I'm sure they know more about engines than I do, so I would be interested in their opinions.
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  #10  
Old 01-25-2017, 07:36 AM
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snopercod snopercod is offline
 
Join Date: Aug 2016
Location: Asheville, NC
Posts: 2,122
Default vibration?

I can't quite see from the second photo, but it seems like there is a lot of unsupported mass connected to the top of the unit. That 1/2" flex hose and the metal object underneath don't seem to be clamped to the firewall. Could that have been what caused the problem?
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