rotax 912is engine failure to develop full power

[facthunter]

There's virtue in simplicity. Good luck tho. Nev

 

 

[Guest Orfboy]

There's virtue in simplicity. Good luck tho. Nev

I suggested to the Bert Flood engineer that new low pressure and high pressure fuel filters wouldn't go astray. It seems that the low pressure filter is an aircraft supplied one and nothing to do with the Rotax. I am not sure what he said about the high pressure one except that he would consult the Pipistrel agent.

That reminds me of the days as a software engineer when things went wrong there was always an argument - its software, no its hardware.

 

 

[Guest Maj Millard]

I assume you guys have viewed the excellent video on supplying a fuel system for the 912Is, posted on Rotaxowner.com. The engine /system is installed in a 701 I believe...but deals with the requirements completely....These guys are at the cutting-edge of the problem........Maj....

 

 

[planedriver]

Spot on Nev.

 

Simplicitity is the essence of reliability, though not necessarily maximum performance.

 

 

[facthunter]

Think I would rather trust a brand new Continental 0-200 than just about anything else to go over water etc You couldn't get one today and I'm not talking of a rebuild unless it was from a low hours and not abused core and built by someone who could effectively "blueprint " it. Nev

 

 

[planedriver]

They certainly seemed to go the distance, probably due to the fact that they didn't wring out every ounce of energy that was possible

 

 

[facthunter]

Some of the EAA speedy planes did. They over revved them to get more power. If you strip the starter off them put a composite fixed pitch prop on and a small alternator and minimum exhaust they aren't too heavy. Nev

 

 

[Guest Orfboy]

Episode 1.I had an episode where I loss power while crossing Bass Strait in my Pipistrel Virus SW with a fuel injected Rotax.

 

To correct the problem two components were replaced, the Key Box and the Fuse Box. All seemed well and the engine ran smoothly on the ground and initially in the air. I assumed that the aircraft was now serviceable and attempted to cross Bass Strait to return home.

 

Episode 2. (two weeks later)

 

Weather dictated an altitude of 2,200 ft to cross Bass Strait. I had been airborne for approximately 45 minutes and was 45 nm off shore when the engine suddenly seemed to labour and lost power. The revs had reduced from 5200 to 4500. and I noticed the Lane A light was flashing on and off.

 

The aircraft started losing height so I tried to increase power. I might add at this stage that failure of Lane A also causes loss of automatic control of the constant speed prop. I tried increasing RPM manually by changing the propeller pitch. It had no effect.

 

Next I increased the throttle in order to maintain altitude but instead of getting an increase in RPM the increased throttle setting resulted in a fall of rev to 4400. I then reduced the throttle setting and managed an RPM increase to 4600, sufficient to maintain an altitude of 1000 ft. and eventually, I was able to slowly climb to 2000 ft.

 

Voltage readings on both Lanes was 13.6 volts. Fuel pressure seemed extremely high (can't remember actual pressure) but I was unsure of what the reading should have been.

 

The EGT for the 4 cylinders were one and three in the green zone, albeit slightly lower that normal and two and four in the red zone marked by crosses (indicating the reading was not working and therefore, was inaccurate).

 

At this point I assumed that the engine was only operating an two cylinders.

 

I managed to get back to an airfield and land without further incident.

 

The engine log has been downloaded and I believe sent overseas by Bert Flood for analysis.

 

I now await a verdict as to the cause.

My saga continues. The fuel pump assembly has been replaced, the Engine Control Unit software updated and a high pressure fuel sensor fitted. Tests on the ground indicated that without the engine running the fuel pressure was within limits. With the engine running the fuel pressure dropped below the minimum limit. As the throttle was increased the pressure dropped further. Maybe that was the cause of revs dropping when airborne as the throttle was opened and increased when the throttle was reduced.

I have suspected the fuel filter for some time and am waiting on a replacement.

 

Nothing to do with my problem but as an aside, Pipistrel are now going to fit future aircraft with a fuel pressure sensor. The benefit in having the fuel pressure displayed to the pilot is that if an engine starts to stutter or run in an abnormal manner, a glance at the fuel pressure will either rule out fuel being the cause or indicated the area of the fuel system to resolve the problem - change tanks, turn on ancillary fuel pump etc. On a Skyview display, a warning of fuel pressure being outside limits will be given and could give the pilot time to take corrective action before the engine does fail.

 

 

[Doug Evans]

This any help ......https://www.youtube.com/watch?v=TzTieV0EvSY

 

This fellow may be able to help with your problem try email for advise ?

 

 

[Tex]

My saga continues. The fuel pump assembly has been replaced, the Engine Control Unit software updated and a high pressure fuel sensor fitted. Tests on the ground indicated that without the engine running the fuel pressure was within limits. With the engine running the fuel pressure dropped below the minimum limit. As the throttle was increased the pressure dropped further. Maybe that was the cause of revs dropping when airborne as the throttle was opened and increased when the throttle was reduced.I have suspected the fuel filter for some time and am waiting on a replacement.

Nothing to do with my problem but as an aside, Pipistrel are now going to fit future aircraft with a fuel pressure sensor. The benefit in having the fuel pressure displayed to the pilot is that if an engine starts to stutter or run in an abnormal manner, a glance at the fuel pressure will either rule out fuel being the cause or indicated the area of the fuel system to resolve the problem - change tanks, turn on ancillary fuel pump etc. On a Skyview display, a warning of fuel pressure being outside limits will be given and could give the pilot time to take corrective action before the engine does fail.

Sorry just coming to this thread very late and I see you mention Pipstrel... have you seen their forum here in OZ where this came up

 

Just a brief quote "There was a fuel pressure reading of more than 60 psi (I believe that normal fuel pressure is about 45 psi) with one pump engaged, and with both pumps engaged, the reading was more than 80 psi. Examination of the fuel regulator, a substantial quantity of black particulates was found in the filter to the point that fuel flow was restricted. The filter was replaced, the black gunk was removed, and at that point fuel pressure returned to 45+/- psi with one or both pumps engaged."

 

 

[viruspilot]

Sorry just coming to this thread very late and I see you mention Pipstrel... have you seen their forum here in OZ where this came upJust a brief quote "There was a fuel pressure reading of more than 60 psi (I believe that normal fuel pressure is about 45 psi) with one pump engaged, and with both pumps engaged, the reading was more than 80 psi. Examination of the fuel regulator, a substantial quantity of black particulates was found in the filter to the point that fuel flow was restricted. The filter was replaced, the black gunk was removed, and at that point fuel pressure returned to 45+/- psi with one or both pumps engaged."

The quote is mine. I own a Pipistrel Virus SW out of San Antonio Texas. I took delivery of this aircraft in April, 2013 and experienced periodic power loss since delivery. Most of the power loss was limited to inability to run both fuel pumps without a loss of power, down to around 4800 RPM at most. When 2nd fuel pump was disengaged, full power was restored. Also, Lane Warning Lights would engage on low power as in pattern altitude prior to landing. In all cases, turning ignition key to Lane A, waiting 10 seconds, and restoring to Both would reset the computer and turn off the Lane lights and resume normal operation until the next event.

 

I took a 1000 mile flight from San Antonio Texas to Greensboro North Carolina (NC) in November. Flight to NC was uneventful as long as both fuel pumps were not engaged. Subsequent sightseeing flights in NC were also uneventful. Upon attempted return to Texas, about 45 minutes into the flight, I encountered some brief sags and surges in power. I landed to inspect, but found no fuel-related cause. I took off again and about 30 minutes later, encountered the same thing. I landed in South Carolina and began a month-long game of "get Rotax and Pipistrel to solve the problem". I could get no one to take responsibility for directly handling it, so I spent hours and $$ travelling back and forth to troubleshoot and forward info to Rotax and Pipistrel for analysis. The consensus was that it was intermittent and safe enough to attempt to fly somewhere for a Rotax repair technician to assist.

 

I attempted to fly it again and after about 1 hour, I experienced a steady loss of power and lane warning light on A. I switched fuel tanks and reset the computer and power resumed normal for about 10 minutes, at which point the steady loss of power resumed. I landed just north of Atlanta GA and told Pipistrel to come get the aircraft and that I would not make any further attempts to do what I considered warranty troubleshooting. To their credit, Pipistrel sent the dealer to pickup the aircraft and ferry it to Lockwood Aviation, an authorized Rotax Service Center in Florida. The dealer reported inability to use both pumps without loss of power, but no symptoms such as I had experienced the last time that I flew it.

 

Upon inspection of the aircraft the following issues were found:

 

1) Fuel pressure with one pump engaged of 60+/- psi. With both pumps engaged, fuel pressure was 80+/- psi. The norm is approximately 45 psi. The fuel regulator and the fuel filter were clogged with a black contaminant. I suspect this was pieces of the fuel line, but this has yet to be determined absolutely. The regulator and fuel filter were replaced.

 

2) There was no fuel pressure sensor, which is recommended by Rotax but not installed by Pipistrel. Pipistrel has installed this fuel sensor with reporting on my Dynon Skyview at no expense to me.

 

3) The fuel line was of a slightly smaller diameter (1/8" smaller, I think) than recommended by Rotax. Lockwood did not have couplings for the recommended fuel line diameter, so they replaced the original fuel line with a new one of the same diameter. I will be reviewing this at a later date. There was no determination at the time of this posting whether or not the existing fuel line had deteriorated. Since I had issues from day one, I am inclined to suspect that when the fuel line was made, there was no attempt to blow out the pieces that were cut to make the line. Future inspections of the fuel filter may corroborate or dispel this theory.

 

4) The ECU was reprogrammed to the current firmware which has been posted as a required service item before January, 2015. I strongly recommend this upgrade sooner if possible. I do not know if it has helped with the Lane Warning errors, but I have had none in the 10+ hours that I have flown it since then.

 

I flew the aircraft back from Florida to Texas (approximately 1000 miles) with no issues whatsoever. No Lane Warning lights, no fuel pressure issues. Fuel pressure stayed between 44-46 psi with one or both pumps engaged.

 

Here are my takes from the process:

 

1) I should have demanded that since it was under warranty, Pipistrel and Rotax come to the aircraft and get it or service it where it sat when it first had a problem in North Carolina. Now that I know it was a fuel pressure problem, it could have failed shortly after takeoff, although it never failed except when at smooth level flight. I now believe that it was just a matter of time when that would not have been the case.

 

2) There needs to be a determination of the actual cause of the fuel pressure problem. Were there contaminants in the fuel line which caused a failure of the fuel regulator or was a faulty fuel regulator the cause of the contaminants breaking off from the fuel line?

 

3) A fuel pressure sensor should be installed on all 912iS engines with constant readings reported to the pilot.

 

4) The Rotax BUDS cable, which is required for both getting data from the ECU and programming the ECU is excessively expensive ($800 for the owner version, $1000 for the mechanic version, and $who knows for the Level 3 Service Center version), in short supply everywhere, and the Level 3 version (there are only 2 in the US) is required to update firmware on the ECU. I bought the Level 2 Mechanic's version just to get the data to send to Rotax and Pipistrel.

 

I love my Virus SW. This has in no way turned me off the aircraft OR the 912iS version of the engine. My aircraft hauls butt. I typically cruise at 140-145 knots at about 3.8 gallons per hour. I have to work to keep it from cruising at 155 in smooth air (163 is VNE). I now know, however that Rotax (and by extension, Pipistrel) need to step up their game on warranty related issues on this engine.

 

Shane Mitchell

 

http://forum.pipistrelowners.com

 

 

[fly_tornado]

where's the old fuel filter?

 

 

[viruspilot]

where's the old fuel filter?

It was kept by the Rotax folks and I am sure more info was provided to Pipistrel than I might be privy to.

 

 

[AFRANIO]

Hello, I have a Tecnam Sierra with 912iS, last week after 2.5 hrs flying, I feel loss power and line A lights get on. I turn off line A and return

 

my fly with Line B. Tecnam Factory send to me a Fuel presure and also a Bypass return fuel. I think the fuel presure was to high and with this bypass the fuel pressure go down. They conect directly the fuel regulator to return fuel line with a very small hole. I open the fuel filter and no deposit in it, I have to get out the fuel regulator and see it.

 

I have get out the fuel pumps and check it in my fuel check machine (I work in a garage) and fuel pumps are ok (presure, amp, noise, etc..). Today I going to received BUDS to conect with my ECU and see the faults.

 

When I resolve my problems I will write again.

 

Regards

 

 

[AFRANIO]

Hi, Ihave alrady recived mi interface, but I´m now loocking where can download BUDS, I can not find in flyrotax.com

 

Any ideas?

 

Thanks

 

 

[AFRANIO]

I have it, thanks