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Differences training, and endorsement logbook entry: implicit due to variant?

Stickandrudderman wrote:

I’m curious, what is it about a turbo that needs managing so carefully? Or, to put it another way, what goes wrong if mishandled?

It is mostly engine temperature management.which is something that you should do in turbocharged (TC) and normally aspirated (NA) engines alike but which is probably even more important in a TC engine.

With a TC engine you get a new instrument labeled TIT (Turbine Inlet Temperature) with a hard limit that you must not exceed. Up high you can produce a lot more power than you would with a NA engine, but you have less cooling so you need to watch your temperatures (CHT) more closely. In order to increase engine life, you may also want to climb with reduced power. On a NA engine the power reduction will take place naturally in the climb, as the air density decreases. Not so with a TC.

You also need to understand the concept of overboost, watch your MP for any overboost condition (some planes have a warning light) and take appropriate action (reduce MP) if it occurs.

After landing you need to let your turbo cool down prior to shutting down.

During the pre-flight, if you have access to the components, you should inspect the turbine and ducts for signs of exhaust leakage.

If mishandled you can significantly reduce the life of your cylinders or kill the turbine. Some failure modes can cause a fire in your engine compartment.

I recently saw a picture of an airplane where a seam in the turbine housing caused hot gases to escape and burn through the cowling, but cannot find it right now.

Last Edited by at 17 Jan 08:02
LFPT, LFPN

Aviathor wrote:

With a TC engine you get a new instrument labeled TIT…

I have flown thousands of hours behind and sideways to turbocharged aero engines (eg. C210, various Senecas, Turbo Seminole, C340, C421, …) but never came across this instrument. But they all had “steam gauge” panels, so maybe the new glass cockpits display it somewhere. The engines however have not changed, so obviously can safely be operated by carefully setting and watching RPM and manifold pressure alone.

Aviathor wrote:

After landing you need to let your turbo cool down prior to shutting down.

Yes. But in most cases, when operating from anything larger than a small private grass strip, this can be achieved by taxiing in using the least possible power. Two minutes at or close to idle power are sufficient (at least according to the manuals of the turbo engines I have operated).

Aviathor wrote:

During the pre-flight, if you have access to the components, you should inspect the turbine and ducts for signs of exhaust leakage.

If practicable. Again, on the turbocharged aircraft I have flown this would have required removal of the engine cowlings. For a C421, removing the cowlings, inspecting the exhaust system and putting them back on requires about a half hour for a mechanic. Per engine. Haven’t ever seen that done during a normal preflight inspection!

Really, operating a turbocharged engine is not rocket science. Watch your red lines and hold the little pointers below them, just like you would with every other bit of machinery. Even my car has a turbocharged engine and no familiarisation was required before I was allowed to drive it

Last Edited by what_next at 17 Jan 10:34
EDDS - Stuttgart

what_next wrote:

but never came across this instrument

I am surprised that those airplanes were not equipped with TIT. I have on flown 4 airplanes with Turbos: PA28RT-201T, BE33, what_next wrote: P210 and COL4. They all had a TIT gauge.

Again, on the turbocharged aircraft I have flown this would have required removal of the engine cowlings.

It does. Which is what I wrote if you have access to the components. It is unfortunately impossible on most airplanes, but some airplanes make it easy or doable. On BE33 and other Bonanzas it is easy. On the Piper Arrow it is doable.

But I agree that if you are used to keeping an eye on your engine temperatures, flying a TC airplane is no different.

LFPT, LFPN

Aviathor wrote:

I have on flown 4 airplanes with Turbos: PA28RT-201T, BE33, what_next wrote: P210 and COL4. They all had a TIT gauge.

The PA28RT-201T I fly does not have a TIT gauge.

EHLE / Lelystad, Netherlands, Netherlands

what_next wrote:

but never came across this instrument.

How did you adjust the TIT without this instrument? My C182 has two TIT gauges, one round instrument from Cessna and a more precise EDM700. I could not imagine to set the correct power setting without.what_next wrote:

The engines however have not changed

This is true. But the newer turbochargers have an automatic waste gate which prevents them quite pretty from overboosting.
Aviathor wrote:

In order to increase engine life, you may also want to climb with reduced power.

Not necessarily. You adjust the temps with mixture and the cowl flaps.

Berlin, Germany

highflyer wrote:

How did you adjust the TIT without this instrument?

I can imagine that you use the EGTs as you would normally do with a NA engine… But then if you do not have TIT you may not have any EGTs either. I suppose you would want at least EGT on one cylinder to find peak.

highflyer wrote:

Not necessarily. You adjust the temps with mixture and the cowl flaps.

Mike Busch limits climb power in his C310 (to 75% IIRC). That is good enough for me to want to do the same
Operation of TC engines at max RPM and WOT for climbing all the way to service ceiling is one reason given for TC engines never reaching TBO without changing the full set of cylinders.

LFPT, LFPN

Cobalt wrote:

EASA FCL.710 (b)
If the variant has not been flown within a period of 2 years following the differences raining, further differences training or a proficiency check in that variant shall be required to maintain the privileges,

It’s worth reading that wording very carefully. Most people read it as:

“If the variant has not been flown within a period of 2 years before the flight in that variant, further differences training or a proficiency check in that variant shall be required to maintain the privileges,”

But that’s not what they wrote.

bookworm wrote:

But that’s not what they wrote.

But did they intend what they wrote? I find it unlikely in the extreme that the variant would not have been flown “within a period of 2 years following the differences traning”.

Of course it could happen, but I find it unlikely to have a paragraph to cover such an unlikely situation.

ESKC (Uppsala/Sundbro), Sweden

It’s worth reading that wording very carefully. Most people read it as:

[…]

But that’s not what they wrote.

Very well spotted!

Airborne_Again wrote:

But did they intend what they wrote?

Nobody is likely to know that better the Bookworm. Irrespective of what they meant, what they wrote is actually very clear, once you realise the point Bookworm made. It in no way whatsoever says what “Most people read it as”.

EIWT Weston

Thank you all for the information, a bit more confused but I am going to bring myself up to speed before anything else, so an instructor can sit with me too, in real terms it makes no difference. Will know more by the weekend.

Thanks again

Ben

Last Edited by Ben at 17 Jan 19:58
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