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  #1  
Old 03-09-2020, 07:22 PM
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Special Delivery Special Delivery is offline
 
Join Date: Feb 2007
Location: League City, TX
Posts: 612
Default Rotax 912iS - Abrupt Drop in Oil Pressure


Log Data Graph by SavvyAnalysis

2/28/2020
Abrupt Drop in Oil Pressure - RV-12iS w/Rotax 912iS Sport engine
Occurred during run-up phase on 1st flight attempt.


The chart above (SavvyAnalysis) reveals an abrupt and significant drop in oil pressure at about the 6min mark. The agreed opinion of the knowledge-base at Lockwood and Leading Edge was that the problem is likely caused by trash entering the oil pressure regulator. Their explanation; unlike the the oil pump on the 912ULS which feeds the integral pressure regulator 'filtered' oil, the new design pump on the 912iS Sport feeds the integral pressure regulator 'unfiltered' oil.

Resolve: Removed oil regulator; found 3-small specks of what appeared to be manufacturing filings and no scoring on piston. Cleaned parts, reassembled, problem solved.

Aside: Based on personal experience, I strongly suggest that you verify the spark plug gaps on your factory new engine. And if you haven't already, download and become familiar with the Rotax MML and MMH manuals available free at Rotax-Owner.com.

The information presented herein is for reference only and is based on our experience.

Have a great day!
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R. E. "Ernie" Butcher
Friends of the RV-1/Eagle's Nest Projects
"Mentors build the student...
Students build the airplane." -Glen Salmon

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and organized for the purposes of promoting, supporting,
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Last edited by Special Delivery : 03-10-2020 at 02:34 PM.
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  #2  
Old 03-09-2020, 08:29 PM
Azjulian Azjulian is offline
 
Join Date: Dec 2015
Location: Scottsdale, Arizona
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Thanks for sharing.

Was this the first engine run ?
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  #3  
Old 03-09-2020, 08:38 PM
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Special Delivery Special Delivery is offline
 
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Quote:
Originally Posted by Azjulian View Post
Thanks for sharing.

Was this the first engine run ?
Not the first engine run... approx 0.6 hr ground testing logged prior to event.
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R. E. "Ernie" Butcher
Friends of the RV-1/Eagle's Nest Projects
"Mentors build the student...
Students build the airplane." -Glen Salmon

Dedicated to the historical preservation of the RV-1 Aircraft
and organized for the purposes of promoting, supporting,
fostering, and engaging in aviation and aerospace education.

www.RV-1.org
www.EaglesNestProjects.org
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  #4  
Old 03-09-2020, 09:54 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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Had I seen a transient in oil pressure I probably would have chalked it up to sensor or wiring issue. Good catch!
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  #5  
Old 03-09-2020, 10:26 PM
Driftdown Driftdown is offline
 
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Location: Clearwater, Florida
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Yes . . . nice catch!
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  #6  
Old 03-09-2020, 10:27 PM
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Special Delivery Special Delivery is offline
 
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Quote:
Originally Posted by RFSchaller View Post
Had I seen a transient in oil pressure I probably would have chalked it up to sensor or wiring issue. Good catch!
Not a difficult catch when you hear "low oil pressure" in your headset. The event was not transient; sustained 42 lb drop at 2300 rpm (55lbs to 13lbs) / slightly higher pressure at increased rpm and as low as 7 lbs at lower rpm.
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R. E. "Ernie" Butcher
Friends of the RV-1/Eagle's Nest Projects
"Mentors build the student...
Students build the airplane." -Glen Salmon

Dedicated to the historical preservation of the RV-1 Aircraft
and organized for the purposes of promoting, supporting,
fostering, and engaging in aviation and aerospace education.

www.RV-1.org
www.EaglesNestProjects.org
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  #7  
Old 03-10-2020, 09:30 PM
RFSchaller RFSchaller is offline
 
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Ernie,

I had a wiring issue with my sensor that gave me random and persistent low oil pressure alarms including ?Bitchin? Betty? screaming ?Oil pressure low? in my ear. I changed out the sensor and the pressure regulator plug before I finally nabbed that gremlin, so I congratulate you again on a good catch!😁

Rich
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  #8  
Old 03-11-2020, 09:37 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by RFSchaller View Post
Ernie,

I had a wiring issue with my sensor that gave me random and persistent low oil pressure alarms including ?Bitchin? Betty? screaming ?Oil pressure low? in my ear. I changed out the sensor and the pressure regulator plug before I finally nabbed that gremlin, so I congratulate you again on a good catch!😁

Rich
Ernie's issue was with a 912iS engine. In many ways similar to a ULS, but in many other ways very different.

All of the engine related data is obtained from sensors that are connected to the factory installed engine harness. There is no builder involvement in any engine wiring other than plugging in a couple of large pre-populated harness plugs. This makes all the sensor connections very reliable.

All of the engine data is then fed to the EFIS system by the engine computers via CAN buss. So short of an actual sensor failure (I haven't heard of any), the probability of an erroneous indication is far lower than it is for a 912ULS.
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Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
FAA/DAR
RV-6A (aka "Junkyard Special ")
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  #9  
Old 03-11-2020, 10:37 PM
RFSchaller RFSchaller is offline
 
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Scott,

Gomen nsai, Sempai!😜

Grasshopper😝
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