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Engine Problems Lycoming IO360 - Robin DR 500

Today we have done a comprehensive run up and data recording of the engine and would like to share the data with you.
This was done after the governor had been replaced ( thus all parts in front of the fire wall have been replaced-sharing full history in a few minutes)

Run up of cold engine, QNH= 987; 7 Celsius

RPM FF MP CHT1 EGT1 CHT2 EGT2 CHT3 EGT3 CHT4 EGT4 OIL T
1000 NA 13 287 1149 334 1162 340 1100 328 1150 174
1500 4 15 277 1223 325 1286 334 1209 323 1288 170
2000 7 20 281 1262 332 1305 341 1236 331 1298 172
2500 12.5 25 308 1292 354 1352 378 1267 359 1352 180
Full (2690) 17 28 336 1303 392 1324 409 1245 382 1323 188

Run up of hot engine after 15 min cooling time, QNH= 987; 7 Celsius, engine start-up OK, engine runs rough

RPM FF MP CHT1 EGT1 CHT2 EGT2 CHT3 EGT3 CHT4 EGT4 OIL T
1000 NA 14 269 1138 317 1170 328 1095 315 1170 173
1500 4 15 262 1203 315 1256 323 1197 315 1250 177
2000 7 20 269 1232 324 1226 332 1233 323 1275 176
2500 13.2 25 301 1272 348 1325 365 1254 331 1330 181
Full (2670) 16 28 337 1280 386 1308 405 1248 370 1307 188

Leaning at 1000 RPM, just before RPM reduction, RPM increases by 100 RPM.

Germany

This is the full repair history of the defect engine or whatever may cause the malfunction.

Summer 2015:
Pilot had to abort take off due to missing engine performance.
Engine was checked and low compression on cylinder no 2 was found. Cylinder was replaced based on assessment by shop. Old cylinder showed evidence of too lean operation.
No change of performance were observed following the replacement.

Autumn 2015:
Magnetos and ignition harness were replaced as rough engine run was observed (as identified by shop A).
Engine run performance did not improve.
Performance observed during test flight: at 70% engine power IAS was 110 kt instead of of 128 kt according to handbook. As recommended by certified shop fuel pump was replaced. Unfortunately this did not improve anything.

Spring 2016:
The plane was flown to shop B under still not satisfying performance. Shop A was unwilling to spend more time on this plane and declared it airworthy.
Due to service bulletin magnetos were overhauled. Valve push rods of cylinders 1 and 2 were replaced as Shop B believed that the ones installed were not the right ones for this IO360 A1B6 engine. During run up at Shop B they damaged the propellor due to stones being sucked in. Consequently, prop was completely overhauled.

Autumn 2016:
After these steps plane was flown to shop A as ARC was due. Shop A issued ARC. Unfortunately, the engine performance was still not improved.

Winter 2016:
The plane was flown to shop C as shops A and B still had no clue but continued sending expensive invoices.
C did the following:
- cleaning of all 4 fuel tanks including inspection with borescope
- fuel hoses replaced
- Fuel spider replaced
- Fuel selector valve disassembled, cleaned and reassembled
- New electric fuel pump
Plane was released airworthy by shop as first run up was OK.
Owner talked to Shop C and did another run up about 15 min after first run up and unfortunately, observed same rough engine run as before.

June 2017
Decision to replace engine with factory new IO360.

November 2017
New engine installed, no change of performance.

Spring 2018
ARC issued by Shop C.
Shortly thereafter owner and technician of Shop C sadly passed away. That has resulted in some delays getting all paper work. Business actually was closed as a consequence of the sudden death. Not surprisingly some unclarity in terms of warranty situation…
As we believed that the problem was caused by limited fuel supply we connected an external fuel tank directly to the engine fuel pump and observed no change. Thus we could exclude that the problem was caused by the fuel supply within the fuel system of the plane. Fuel pressure was also measured with an external manometer and found OK, albeit at the lower range (20 PSI).
The plane has been grounded throughout the year.

Shop D was asked to take care of the problem. They came by car from an airfield about 400 km away.
They found out that the brand new fuel injector was defect (low output towards spider). Fuel injector was found to be defect: several bearings were replaced, a drive shaft was bent and replaced.

After installation no change! Sadly, the technician of shop D (a highly experienced engine expert) was diagnosed and submitted to hospital. He has not been back to work since then and, unfortunately, Shop D also discontinued business.

A new hypothesis was that the exhaust system could be restricting engine performance as there were loose parts within the exhaust system. Also technician D had mentioned that heat may have caused malfunctioning/reduced engine performance. The exhaust system was thus replaced with a new one. No improvement.

Finally, after all these years the governor was due for overhaul, which was recently done. Again, this did not improve the situation.

The owner has spend almost 100 k on repair.

Does anyone have a clue????

Germany

What a very sad story. I sincerely hope you have a proper resolution very soon. I also have to say I have great admiration for your persistence.

Last Edited by Fenland_Flyer at 08 Dec 15:23
UK, United Kingdom

ignition coil, intake system, carburetor. The engine is new. The prop is new. The fuel system has been checked. The fuel pump is new. All parts are new. But why does the heat still make the engine rough / weak ?
What about cooling air flow ? Baffles ? Does the engine compartment get hotter than normal ? Not the cylinders, but the air around the engine. If that’s too hot, it has an influence onto ?

Yes: Ignition system, intake system, carburetor….

Last Edited by EuroFlyer at 08 Dec 16:18
Safe landings !
EDLN, Germany

This is simply beyond belief!

4 shops can not diagnose an engine problem and just experiment on the cost of the owner?

Has the old engine ever been taken off the airplane and put on a test stand to see if it works outside the airplane? Has the same been done or considered for the new one after the effect persisted? Which should be under warranty may I add?

Then a factory new engine shows the exactly same behaviour? And on that factory new engine the fuel spider is defective? I hope at least this was replaced under warranty?

When you say a factory new engine was installed, what of the old engine remained? Magnetoes? other components?

If everything front of the firewall has been replaced as you say, there are imho two more things to do:

If you take the complete engine enclosure off and re-run the test, can you replicate the defect? With the termic problem which appears to trigger this roughness, i wonder if there is a problem with the airflow under the cowling.

Have you checked the electric wiring to and from the engine? All ignition cables and harnesses?All spark plug caps have been replaced? I heard a story of an engine doing something similar under thermic load and after debugging, one cap of one spark plug was found to have a hair crack which opened up under heat. After it was replaced, the defect stopped.

The last thing I would do is to remove the engine with magnetoes, governor and prop and put it onto an engine test stand. If it works there as advertized, it has to be airframe based.

This sordid story tells a horriffic tale of incompetence of multiple shops who obviously have no idea and are experimenting on the cost of the customer. This is totally unacceptable but shows why so many owners simply give up over such a defect.

Last year we had a similar thing with the airplane being impossible to start. The shop, who usually is very competent, was unable to find the fault despite us taking action with experts and were told to replace the showers of sparks box. The shop insited that it was ok. After several months of trial and failure, I odered the bloody thing myself and had them change it. The plane worked ever since. We found a way acceptable to all to sort the financial side of this, as some of the work done was justifiied as defects were found, albeit they had nothing to do with the original problem.

The owner of that poor robin now needs to take charge and talk to people who know engines. Tinker shops have no place in this business.

LSZH(work) LSZF (GA base), Switzerland

@NorthernDirk

It is has to be a an installation related issue, ie not engine related.

Have the fuel tank and vent lines pressurised and check air flow coming out, Fuel caps should allow a little venting, but nothing like the vent line will allow.
I am not familiar with Robin aircraft airframe, but in case it has not been looked into yet, now is the time.

I did ask the Q about fuel flow being actually known, early on…

Administrator
Shoreham EGKA, United Kingdom

@peter

as we don’t have a more precise measuring opportunity
we have to relay on the cockpit instrument displayed numbers…

RPM FF MP
1000 NA 14
1500 4 15
2000 7 20
2500 13.2 25
Full (2670) 16 28

Germany

@euroFlyer
* What about cooling air flow?

we have already thought about it – but how should we measure this and how should we interpret the data?

but it is certainly a thought that we should continue!

Germany

as we don’t have a more precise measuring opportunity
we have to relay on the cockpit instrument displayed numbers…

My Q was whether there is a real fuel flow meter.

The standard GA fuel flow is a pressure gauge, fed from the extra port on the fuel distributor. This just shows a proxy for fuel flow.

If you had a Shadin/JPI type of fuel totaliser, you would have an independent readout of the fuel flow, and with an EGT gauge (say an EDM700) you could lean the engine for peak EGT and then the power is proportional to the fuel flow. There is no escape then.

I suspect this awful story – thank you for posting it – is a case of a maintenance company(ies) saying they have done X and they have not actually done X. This is at the root of stories like this. It is a tragedy to read. The other thing at the root of these stories is the owner not being present, or being present and not understanding.

Administrator
Shoreham EGKA, United Kingdom
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