Socata 235E with O-540 b4b5 problem

[Alexey Sharadkin]

Hello

new user of O-540 here.

O-540 engine, 25 hours after OH
New spark plugs. oil - 20w50.
Fuel - 92

The problem in the following:
The temperature on the ground about 20C, cylinder temp on tow 205 C, all towing in max mode.
Towing to the release - ok.
While descending cylinder temperature drops to 130-140 C degrees.
Landing, move throttle to 2000 rpm to fire the spark plugs, all is ok.

At take-off after about 20 seconds of max.rpm start very loud claps.
Also goes vibration - unwind the screws that secure the hood.

They disappear after 30-40 seconds of towing, when the temperature of the cylinder goes up to 200 degrees.

Through trial and error found a way - after landing I change mixture to LOW to raise the exhaust temperature to the maximum, heated cylinders
to 180-190, then claps less and they will disappear faster.
But this takes time, and am not sure that this is good for the rapid heating of the engine.

Can you recommend something?

Some other considerations?

[Chris Rollings[_2_]]

What airspeed and power setting are you using for the descent?

At 07:54 18 September 2014, Alexey Sharadkin wrote:
>Hello
>
>new user of O-540 here.
>
>O-540 engine, 25 hours after OH
>New spark plugs. oil - 20w50.
>Fuel - 92
>
>The problem in the following:
>The temperature on the ground about 20C, cylinder temp on tow 205 C, all
>towing in max mode.
>Towing to the release - ok.
>While descending cylinder temperature drops to 130-140 C degrees.
>Landing, move throttle to 2000 rpm to fire the spark plugs, all is ok.
>
>At take-off after about 20 seconds of max.rpm start very loud claps.
>Also goes vibration - unwind the screws that secure the hood.
>
>They disappear after 30-40 seconds of towing, when the temperature of the
>cylinder goes up to 200 degrees.
>
>Through trial and error found a way - after landing I change mixture to
LOW
>to raise the exhaust temperature to the maximum, heated cylinders
>to 180-190, then claps less and they will disappear faster.
>But this takes time, and am not sure that this is good for the rapid
>heating of the engine.
>
>Can you recommend something?
>
>Some other considerations?
>
>

[Alexey Sharadkin]

> What airspeed and power setting are you using for the descent?

2000 rpm, 180 km\h

[Dan Daly[_2_]]

On Thursday, September 18, 2014 9:18:38 AM UTC-4, Alexey Sharadkin wrote:
> > What airspeed and power setting are you using for the descent?
>
>
>
> 2000 rpm, 180 km\h

http://www.helium-group.com/wp-content/uploads/2010/04/Lycoming-POH-Tables.pdf says minimum fuel grade is 100/130. Discussion at http://www.pprune.org/private-flying/419030-lycoming-io540-mogas.html suggests detonation and per-ignition problems with 92. Have you tried it with 100LL and compared how it runs?

[Alexey Sharadkin]

http://www.helium-group.com/wp-content/uploads/2010/04/Lycoming-POH-Tables.pdf says minimum fuel grade is 100/130. Discussion at http://www.pprune.org/private-flying/419030-lycoming-io540-mogas.html suggests detonation and per-ignition problems with 92. Have you tried it with 100LL and compared how it runs?

For O540 B4B5 minimum fuel grade 80\87.

[James Thomson[_2_]]

At 06:31 20 September 2014, Alexey Sharadkin wrote:
>http://www.helium-group.com/wp-
content/uploads/2010/04/Lycoming-POH-Tables.=
>pdf says minimum fuel grade is 100/130. Discussion at
>http://www.pprune.or=
>g/private-flying/419030-lycoming-io540-mogas.html suggests
detonation and
>p=
>er-ignition problems with 92. Have you tried it with 100LL and
compared
>how=
> it runs?
>
>For O540 B4B5 minimum fuel grade 80\87.

I suspect your problem may be the fuel. What is the specification of
your fuel? Lycoming Service Instruction SI1070S does not approve
any 92 grade aviation fuel. They approve automotive fuels with an AKI
(average of MM and RM octane ratings) at least 93 for the 0-540-B.
Check the SI for more advice.

[Alexey Sharadkin]

> I suspect your problem may be the fuel. What is the specification of
>
> your fuel? Lycoming Service Instruction SI1070S does not approve
>
> any 92 grade aviation fuel. They approve automotive fuels with an AKI
>
> (average of MM and RM octane ratings) at least 93 for the 0-540-B.
>
> Check the SI for more advice.

If that's too low AKI - there will be detonation, vibration, high CHT\EGT ets.
And it will for all time. And not for 30 sec, no?

We worked on that fuel in summer, and have no troubles then...

[[email protected]]

On Thursday, September 18, 2014 3:54:36 AM UTC-4, Alexey Sharadkin wrote:
> Hello
>
>
>
> new user of O-540 here.
>
>
>
> O-540 engine, 25 hours after OH
>
> New spark plugs. oil - 20w50.
>
> Fuel - 92
>
>
>
> The problem in the following:
>
> The temperature on the ground about 20C, cylinder temp on tow 205 C, all towing in max mode.
>
> Towing to the release - ok.
>
> While descending cylinder temperature drops to 130-140 C degrees.
>
> Landing, move throttle to 2000 rpm to fire the spark plugs, all is ok.
>
>
>
> At take-off after about 20 seconds of max.rpm start very loud claps.
>
> Also goes vibration - unwind the screws that secure the hood.
>
>
>
> They disappear after 30-40 seconds of towing, when the temperature of the cylinder goes up to 200 degrees.
>
>
>
> Through trial and error found a way - after landing I change mixture to LOW to raise the exhaust temperature to the maximum, heated cylinders
>
> to 180-190, then claps less and they will disappear faster.
>
> But this takes time, and am not sure that this is good for the rapid heating of the engine.
>
>
>
> Can you recommend something?
>
>
>
> Some other considerations?

Higher density altitudes in the summer - the higher the density altitude, the lower the octane required to suppress detonation (that's why Colorado has 85 octane as regular, lower is 87...). You were probably on the edge.
Again, have you tried 100LL to see if that cures the problem?

[Alexey Sharadkin]

Not yet... ****ty weather.
Will try for sure, just dont fully understand the idea...

But - will try