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Engine Problems Lycoming IO360 - Robin DR 500

Hmmm, I know I am a bit paranoid about it, but we had some troubles in recent times with mag coils. Did you ever do a mag test AFTER flight before shutting down ?? It is not much point in doing it before flight when all components are cold so since some time we do the mag test after vacating the runway and on the taxiway. That will give you a clue if the capacitor or the coil were still OK. They typically die with heat and that takes a quarter or half an hour to show. So the loss of power could be because you are operating on only one magneto in the air – or on the ground with closed cowling at higher temperature. Anyway, do a test for checking this possible defect. Vic
vic
EDME

Do you have an engine monitor that does data logging that you could extract?

NorthernDirk wrote:

Even the propeller has been overhauled, as the plane was rolled into a taxiwayamp by the maintenance staff…This happened during one of the many attempts of an maintenance shop to solve the problem

This would require not only the propeller to be overhauled but a complete shock loading inspection! Dont let the shop get away with that…

Check the exhaust system for insecure baffles in the muffler.

Check the flexible fuel lines with a ball bearing for flow in both directions and then do a flow check on the whole airframe fuel system.

Still no answer regarding engine instrumentation… something fishy is going on here.

The analog fuel flow readout is just measuring the pressure coming out of a spare port of the flow divider. So if the injectors were all blocked, you could still see “flow” indicated. Only a proper flowmeter will show fuel flow.

Administrator
Shoreham EGKA, United Kingdom
Still I cannot see the temperature relation. New engine – but still same old magnetos ??? One reason to suspect ignition related problem, high temperature typically showing this . Vic
vic
EDME

I’ll try to summarize:

The report is:

-Very marked loss of power on the ground and in the air, only when hot and cowled. Also when using an independent fuel system and with aux electric fuel pump on or off.
-The indications are:

Loss of airspeed (in the air)
Loss of RPM (on the ground)
Loss of FF (-2GPH)

  1. We need to validate the FF indication and find out whether this is a spider-pressure indication or a volumetric flow indication (the former would be a needle, instruemtn connected to hose from spider, the latter would be digital, connected to a small turbine sensor in the main fuel feed hose to the injector/throttle body). If both are available, then an indication of any differences in relation to the event is needed.
  2. We need to find out whether the power loss is also accompanied by a change in MP or not
  3. An indication of EGT variation upon power loss would also be helpful

This information will direct troubleshooting in one direction or another.

Last Edited by Antonio at 20 Nov 16:34
Antonio
LESB, Spain

Back in my schooldays, when I was a tinkerer buying and selling used mopeds and cars (lots of times with aircooled little carburetor engines), an engine losing power when hot meant mostly:
- a problem with the ignition coil
- insufficient compression – to be checked while engine is hot,
- intake system getting hot and sucking in hot air, resulting in loss of oxygen
- or a problem with the mixture becoming too rich when hot, comparable to constant choke. Since there’s no choke, there might be a problem with the mixture knob

I would strongly suggest to look at the ignition, intake and mixture control. After all, it’s an aircooled boxer engine :)

Last Edited by EuroFlyer at 21 Nov 13:47
Safe landings !
EDLN, Germany

Thank you for all the answers and thoughts on our problem….I have been very busy for the last few days

At the weekend we meet once again at the Aircraft, and log everything more precise !
As I have already mentioned, is the governor still in the overhaul, as soon as it is installed we know more!

The exaust is brand new, magnetos and engine have less then five hours…

Germany

Polypragmatic therapeutic approach without proper diagnosis. You really replaced all the periphery of the engine and the engine itself?

Last Edited by a_kraut at 22 Nov 19:10
Bremen (EDWQ), Germany
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