LANE B FAULT

by Luiz Silva in 912iS Technical Questions 7 years ago

I was flying and the LANE B light turned on steady.

In the FAULTS page it read the following message :

LANE B SENSOR STATUS
MANIFOLD AIR PRES

I think the manifold sensor for LANE B failed and therefore the LANE B computer stopped its four injectors, leaving LANE A to double the flow, and therefore the fuel flow increased from 13 liters/hour to 16 liters/hour.

any suggestions, help ???

LANEBFAULT.jpg (You do not have access to download this file.)

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Re: LANE B FAULT

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

The fuel injectors are not necessarily being disabled.
On any fault, the ECU will discontinue ECOnomy Mode and revert to POWER Mode. Your Fuel usage will increase due to the mixture being enriched.

There is a high possibility that the MAP sensor connector has become loose.
It is easy to unlock the connector accidentally.
There is a Service Instruction offering optional Clamps to prevent accidentally unlocking the connectors.

Check to make sure that the connectors on the MAP Sensors are secure.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: RotaxOwner Admin

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Re: LANE B FAULT

by Luiz Silva » 7 years ago

Luiz Silva

1 3 0

I am quite impressed at the expertise we can find here at the forum !!!

Thank you very much Bill, I think you're on the right track and this FAULT may be just what you have pointed out.

One more question, I kept flying both times that FAULT appeared and although ROTAX is very clear about STEADY LANE lights inflight, I felt very secure since it was very clear to me all other sensors and functions of the LANE B were fine, not even speaking I still had a healthy LANE A, was I correct in my reasoning ?

thanks

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Re: LANE B FAULT

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

The beauty of a fully redundant system is what would otherwise be a catastrophic failure becomes a minor incident.
Consider the MAP sensors.... The ECU looks at the throttle position and the MAPressure.
It looks up in its ECO or POWER table how much time to fire the injectors at each intake cycle.
Now if one MAP sensor gives an obvious bad reading it just ignores the reading and uses the other sensor and lights the alarm.
In theory, you could fly like this forever, what you do not have anymore is redundancy.
If one sensor just failed the other Might or Might Not be far behind. A big unknown.
If the second sensor were to go out of service, the ECM becomes blind and (Just Guessing here) blindly delivers full throttle fuel quantities.
The engine might run reasonably at full power but would start to flood as you backed off the throttle.
An engine limited to full power is way better than no power!

The cause of the failure is an unknown. The recommendation is to land as soon as practicable.
You do not need to land in the nearest field, but you are now on notice that a total failure MIGHT be in your near future.
Do You Feel LUCKY!!

If it turns out to be a loose connection on one MAP sensor you would have been OK continuing to the destination.
If it turned out that BOTH connectors were loose and the other one was minutes from also disconnecting... Bad choice.
If it turned out to be the engine was on fire and the other cable was about to burn through... another Bad choice.

The issue is that the ECM does not know the cause and recommends the most cautious solution. Land Soon!
You have more information as the pilot and can decide as you see fit depending on circumstances.

In any event with a steady lane light, I would continue cautiously, not touch the throttle, and not give up one foot of altitude until I was within gliding distance of a runway.
It would be reasonable to request landing priority due to engine problems and forgo the pattern take a straight-in approach.

Caution is always the best choice.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: LANE B FAULT

by Luiz Silva » 7 years ago

Luiz Silva

1 3 0

Strangely I still felt safer than flying with a single carburator ! LOL But I will take you words into consideration very seriously since your comments make a lot more sense than my intuition !!!

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Re: LANE B FAULT

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

In truth, you were quite safe and might very well have been able to fly indefinitely, However...

Consider if you were flying a twin-engine aircraft.
Just after takeoff, you lose one engine.
Do you continue your planned 6-hour flight because the plane will fly just fine on one engine?
Or do you turn around and land and get the engine repaired before continuing?

Losing one MAP sensor or one engine just means you lost redundancy.
Redundancy is your insurance policy, and you just collected the benefits.
It is time to go buy another policy! ;)
~ ~ ~
Have you had a chance to inspect the connectors?

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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LANE B FAULT

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