Feedback on current DA42 ownership costs

[antoinemo]

Hello Diamond Aviators,

I've been researching the forum for inputs as I build a model for ownership costs of a DA42. Going from a Lycoming DA40 to a Diesel DA42 has obviously many differences in the ownership model. I've found some good information on the forums (especially @chili4way's DA40 budget) but some of it outdated (and we all know how much aviation costs have risen in the last 2-3 years..!), had some high level numbers (not very precise unfortunately) from our DSC, and the old Great Lakes Diamond page had some helpful inputs in the labor hours but the parts costs are also outdated. I thought I would share a first version of my spreadsheet to get some feedback on my hypotheses (especially the maintenance items), see if I'm missing anything in the model. and maybe it can also be helpful to others in the same situation.

Some context:
* We're looking at an Austro-engined, GFC700 (factory or upgrade) DA42, ideally a non MSB 043 (even if it seems like we're getting closer to a fix).
* The plane will be on leaseback with a flight school thus the conservative fuel burn numbers, high insurance costs, consumables, expensive 100hrs.
* I'm not really factoring any unexpected maintenance just yet (apart from the annual which would most likely be one of the 100hr intervals) but this is something we're obviously aware of, especially in a flight training environment.
* For maintenance items, the 200/300/600/900 hrs inspection and TBR are only the marginal cost of that inspection of top of all other inspection that are due at the same interval.

I'm especially looking at feedback on the maintenance items - cost of parts, labor hours, etc.

Here is a screenshot of the current numbers:


And here is the spreadsheet. It should be possible to make a copy should anyone like to do that.

Thank you all for the help!

[Chris]

The spreadsheet looks pretty good to me at first glance. Here are some comments based on comparing numbers with the estimate I received a few days ago for my 1200hr service.

The prop overhaul cost seems slightly low to me. I've had quotes as high as $12.5k per side (in California) and am currently getting my props overhauled at $11k per side plus $350-400 per side (estimated) for in-shop labor for unmounting/mounting/shipping/etc.

I didn't see any budget for TVD inspection and possible flywheel replacements at 600 hours.

Air filter replacement ($700 total) on your spreadsheet was slightly higher than my current estimate ($500 total). Same for gearbox oil/filter change at $2200, though that one is harder for me to break out in my current estimate since part of it is combined with other tasks ($800 + $149 oil + ??).

My bonding inspection was estimated at $800 vs $1200 on your sheet.

I didn't see anything for hydraulic pump filter replacement. I don't recall off-hand if/when that's scheduled, but it's showing up on my 1200hr estimate as a $1063 line item ($862 parts + $201 labor).

I would probably budget for more main gear tire replacements, especially if being used for training. Flat-spotting is not uncommon for less-experienced DA42 pilots.

[tjmoody]

I would pressure-test your annual insurance estimate. The $12k you have in the model is 1.6% of hull value. That is ok for owner-flown operations. However for training operations, I've heard numbers as much as 2-4x higher. I've never gotten training insurance on my Diamond (but I did for a previous non-Diamond plane) so take what I am saying with a grain of salt but it is definitely a number I would check on early with your broker.

[nickname]

As an operator of 2 DA42s flying 50-100 hours per month each, most of the figures are far too low. There are also unpredictable failures that could affect the model significantly that seem to be common in a training setting.

[antoinemo]

Thank you to all 3 of you, very helpful.

- Thanks for the link re the TVD/flywheel inspection. I had not realized that they had such a high failure rate even if no windmill restart is performed. I've added that to the sheet.
- Regarding the other items, our local DSC can be a little bit steep pricing-wise so I'm trying to be conservative with the estimates
- On insurance, our broker has given us a ballpark of 2% of hull value for our operation (I think the number I had on the spreadsheet was for a lower hull value aircraft) but with many restrictions in terms of MEI total experience and time in type, no solo rentals, etc. Certainly something to check - I'll get back to them and get a proper quote established to make sure they didn't miss anything there.
- And thanks for pointing that out Noah. I'll beef up the numbers across the board. We're trying to price the "best case scenario" numbers, and will layer on top of that the unforecast similar to the other types of aircraft that we operate. If there's any training-related maintenance item that comes to mind I'm certainly curious to know.

Thanks again for the help!

[nickname]

Thank you to all 3 of you, very helpful.

- Thanks for the link re the TVD/flywheel inspection. I had not realized that they had such a high failure rate even if no windmill restart is performed. I've added that to the sheet.
- Regarding the other items, our local DSC can be a little bit steep pricing-wise so I'm trying to be conservative with the estimates
- On insurance, our broker has given us a ballpark of 2% of hull value for our operation (I think the number I had on the spreadsheet was for a lower hull value aircraft) but with many restrictions in terms of MEI total experience and time in type, no solo rentals, etc. Certainly something to check - I'll get back to them and get a proper quote established to make sure they didn't miss anything there.
- And thanks for pointing that out Noah. I'll beef up the numbers across the board. We're trying to price the "best case scenario" numbers, and will layer on top of that the unforecast similar to the other types of aircraft that we operate. If there's any training-related maintenance item that comes to mind I'm certainly curious to know.

Thanks again for the help!

As a reference point, we pay approximately 3% of hull value for a training & rental policy and it's "as approved by" with no minimums - but that's due to a collective thousands of hours of multi dual given amongst our instructor group with zero accidents, incidents, or claims. So I'd budget for 3% or more.

[nickname]

Further thoughts after having some more time to look through things:

• I would just include your oil change in the 100 hour inspection since it's done concurrently. Buy Castrol Edge 5W30 A3/B4 in the POH to save money compared to Aeroshell Diesel Oil. It adds up in the long term, especially for consumption between oil changes.
• Buying a 20L pale of the gearbox oil can save some money as well.
• As discussed on other threads, just source the parts yourself instead of buying 100 hour kits.
• Budget for an additional 5-10 hours of labor at a minimum for squawks addressed at 100 hour inspections. Parts cost for said squawks could vary wildly.
• I recommend only replacing the high pressure pump on condition unless warranty or insurance requires it. It's in Chapter 5 and not required to do legally speaking.
• Budget for fuel injector replacement is 10-20% low on parts cost and 50% high on labor cost.
• Expect to replace brake linings every 50 to 100 hours. At least they're cheap and you can do it yourself very easily in 20 minutes.
• Expect to replace main tires every 100 to 150 hours, and don't forget tubes, those seem to be left out.
• The model left out ECU battery replacement every 12 months and the artificial horizon backup battery every 24 months.

[antoinemo]

Fantastic Noah, this is very helpful. Much appreciated!