CD-155 Jet-A (Diesel) engine in Cessna 172 or Archer DX

[Kulwin Park]

Unsure whether I'm in the right forum, but I wondering whether anyone has had experience flying or operating the new Cessna 172s or Piper Archer DXs with the CD-155 engine fitted??

What are the flight differences? Are the engine controls better?
Do you know if the maintenance costs are cheaper? And servicing periods are extended or shortened?

Seriously considering buying one as hard to get Avgas at every little country airstrip. Thoughts anyone
Cheers, KP

[Pilot DAR]

Hi KP,

Yup, this is the best place to ask...

For myself, only the Thielerts in the DA-42. I liked them, but I was not paying the bills!

[Jhieminga]

I've flown a few Cessnas with Thielert diesels. Overall it is a very simple beast to operate but there are a few things that are different. If you are just using the aircraft to cruise around and have lunch, you probably won't notice these differences all that much. If you are operating for training purposes, you'll find them. One thing is that the aircraft is less willing to slow down. The prop will continue to keep the RPM high and you will still have a bit of thrust from it, you'll have to decelarate below 60kt to get the RPM down and then all of a sudden your glide path gets steeper. Keep that in mind if you want to use smaller fields. Also your weight carrying capacity will be quite a bit less than on the Avgas fueled version. The other gotcha is that almost every section of the Emergency Procedures ends with 'land as soon as practicable, expect an engine failure' as you will need electricity to keep the engine running.

As for engine controls, you will not be able to set power 'by ear' as the sound will not change. That means paying more attention to the thrust indication on the engine display or learning to set power by remembering lever positions (1cm forward equals this much power for example).

Hope this helps.

[Kulwin Park]

Thanks @Jhieminga thats good to know about the prop not willing to slow down. A few crabs, and she'll be at 60kts no worries!

It must be so much easier not worrying about the mixture settings tho.

I wonder why they stopped the new SMA engines being fitted into new Cessna 182's. That would've been my 1st choice, but dollars would've been my 1st problem, as they started at half a mill I bet!

[Downwind Lander]

.
Gordon Bennett, you can't shut the engine back in a hurry? There must be some heavy duty benefits to balance out that.
.

[madlandrover]

Bear in mind that the Thielert/Centurion engines use a constant speed propeller (although speed is ECU controlled rather than pilot controlled). As a result, when reducing power towards idle they will maintain c.2000 prop RPM at higher speeds by setting a progressively finer prop pitch - thus giving a noticeable braking effect. They can be a slightly acquired taste since initial power reductions will give the expected RPM reduction, while reductions towards idle will give an RPM increase. This was something we used to cover in differences training when instructing on them.

Personally, having flown both the early 1.7 and later 2.0 variants, the later variants are far better as long as ongoing maintenance is budgeted for. The day to day costs are lower but some bills can be a bit scary. After 1000+ hours on them in various airframes I would not own one myself but can see how the simplicity and fuel economy would work well for others.