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Upgrading DA42 with CD-155 engines

Although we have few similar threads on this topic I agreed with @Peter to make this as separate article because it’s related to particular aircraft – my DA42 SE-MAD.

Introduction

I made my decision about this upgrade long time ago. Basically, it was my intention since purchasing DA42 because at that time (July 2014) it looked that CD-155 (at that time Centurion 2.0s) STC for DA42 would be approved soon, since Mr. John Crosby had been in the final stage of the process. I still had some 500 hours available on current CD-135 engines and reasonably hoped STC would be available before I had to replace the engines. Diamond didn’t have any plans on developing such STC at that time (or they didn’t want to share any information about that), since they were pushing their own upgrade with Austro engines.

There were three main reasons why I chose CD-155 over AE300:

  • much lower price of the upgrade (this gap has widened even more as time lapses)
  • very close if not better performance in terms of climb and speed
  • maintaining same weight and consequently same stall and other low speeds

Obviously, the only reason why to replace CD-135 with CD-155 instead of going only for new CD-135 was getting better performance.

Operating costs are maybe in AE300 favor (due to TBO rather than TBR) but having in mind initial price difference and 1800 (AE300) vs 2100 (CD-155) flight hours and possible extension, I don’t see much advantage of AE300 for private use. Also, knowing Diamond’s attitude towards customers once airplane sales is done, I’m not sure that anybody can guarantee reasonable overhaul cost for AE300 in future. What ensures me in such thinking is dramatic rise of AE300 upgrade over the years – it started with €125.000 six years ago to reach something between €320.000 and €400.000 without VAT, depending if you go for just NG (engine replacement only) or –VI (full upgrade, including GFC700).

Finally, in January 2015 EASA approved this STC and issued official document on it. Interestingly, very soon after that (March 2015) Diamond and Continental Motors issued press release with information that Diamond’s own STC for CD-155 was approved by EASA. That opened more options (at least theoretically) and I was under impression that competition would result in comparable pricing.

I was closely watching the situation and while Diamond did only one conversion (the one for STC) Mr. Crosby did several ones. According to information from different sources the majority of DA42 users with CD-135 engines just replaced them with new ones, benefiting from the lowest cost – approximately €90.000. The price of my upgrade was agreed long time ago when I first met Mr. Crosby and when we shook our hands and it’s some 40% higher than simple CD-135 engine replacement. The reasons for higher price are obvious – CD-155 engines themselves are more expensive than CD-135 and there are some cowling, radiators and exhaust system changes that are needed.

In November 2017, I made final plan for last few hours left on engines and asked final quotes from Diamond (for CD-155, NG, and –VI upgrades) and from Mr. Crosby. While Mr. Crosby’s offer was as same as we agreed long time ago, I was quite surprised with Diamond’s offers. CD-155 upgrade was 50% more expensive, while NG and –VI upgrades were in range specified above (€320.000 and €400.000 without VAT). So I didn’t have reason to think much and question my initial decision – it was just the last check of current pricing for peace of mind.

I accepted Mr. Crosby’s offer and we closed the deal beginning of December 2017 with idea of actual performing upgrade in spring 2018. I paid the down payment in exact amount of price of CD-155 engines which was of course used for purchasing new engines because Continental Motors required full payment when ordering. The engines were purchased in December 2017 to avoid usual price increase in new year with planned delivery in March 2018.

Last Edited by Emir at 18 Apr 14:39
LDZA LDVA, Croatia

Part one

The choice of the shop was very easy – Aeroservice located at Bled LJBL airport in Slovenia, one of the few shops which has qualified for performing CD-155 upgrade. Besides being geographically close, it’s the shop which has been maintaining my DA42 since I purchased it. On top of that, they have successfully upgraded several DA40, DA42 and C172 aircrafts with CD-155 engines.

My upgrade was scheduled for mid-March, aligning my schedule with shop’s availability which was just about to finalize the same upgrade for Swiss customer. Also, that was aligned with engine delivery time and I only could hope that all parties would keep up with schedule.

Luckily beginning of March Mr. Crosby informed me that engines had already been delivered to Aeroservice and that upgrade could start whenever approved by the shop. So, I flew there few days before agreed date and the works started immediately. First of all, propellers were removed and sent to MT Propeller for rebuild – changing blades while spinner and TKS parts were reusable. I opted for new Scimitar propellers because I had unique opportunity to exchange them relatively cheap.

This was followed by removing old engines and preparing lower cowlings for modification.

And of course, installing two new CD-155 engines.


In the meantime, while waiting props (delivery scheduled for April 18), all tasks related to airframe scheduled maintenance were performed as well as polishing wings and fuselage.

Last Edited by Emir at 18 Apr 14:44
LDZA LDVA, Croatia

Very interesting, thanks for sharing.
Your 42 is SE registered and you fly in Croatia?

always learning
LO__, Austria

Hi Emir,
Please keep it coming, great to see Crosby’s STC finds applications.
More than interested with the development of your story

EP..

So am I and not knowing anything about DA42’s but I do think this looks a very good conversion.

Your 42 is SE registered and you fly in Croatia?

Yes. No problems with CAA of any of the countries.

LDZA LDVA, Croatia

BTW props are delayed for few days – I don’t understand why and I’ll ask for the explanation.

LDZA LDVA, Croatia

Could you take a few pics comparing the 135 and 155 engines?

EFHF

I’m not sure about taking pictures for comparison because new ones are in and old ones are probably packed for disposal – I’ll be in the shop next week. But these are supposed to be the same engines with some differences in software, radiators and exhaust.

Last Edited by Emir at 21 Apr 17:33
LDZA LDVA, Croatia

The CD-155 have beefed up oil coolers which is why one needs to modify the cowling.

LFPT, LFPN
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