2001 DA-20 C1 questions

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YCCA
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2001 DA-20 C1 questions

Post by YCCA »

Hello.. I’m looking for a little help on a few topics.. I just recently bought 2001 DA-20 C1 with an IO-240 overhauled engine and prop with about 90 hours and have a few questions.

1. The oil temp and CHTs are way low. Oil temp only gets to the bottom of the green at high power settings and the CHTs never make it to the green arc

2. What am I looking for when I test the alternate air? I can’t find it anywhere or maybe just missed it.

3. The left wing has some play in it. I found the tolerance in the MX manual but is this normal after 4500 hrs? Mech who just did the 100hr said it was getting close

4. How do I know if the electric fuel pump is working airborne? On the ground I can hear it but when I turn it on the pressure does not move at all.. is this normal?

Thank you for any help you guys can provide... Jeff
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Re: 2001 DA-20 C1 questions

Post by RMarkSampson »

Jeff,
I'll take a stab:
1. I installed an EDM-900 so I am spoiled with digital values. Low temps are certainly better than high temps but the only way to know what temps those analog gauges are reading is to calibrate them. A rough way to do that would be to pull the oil temp sensor and put it into a pot of boiling water - at least that way you will have a baseline IVO 212F. My oil temp normally runs 170F'ish so it would run below the boiling water max. A thermometer that can handle the boiling water temp would also allow you to calibrate readings below 212F. CHT run around 300-320'ish so it becomes harder to do a low tech calibration for those temps.

2. Your airbox has a filter side and a non-filter side. No change is good. The engine really should not change rpm between the two - otherwise something is amiss (i.e. one side is clogged).

3. Play? are you talking about the entire wing or are you just checking tolerances on the ailerons? Either way I recommend doing the 1000 hour maintenance - especially if you have concerns about how the wings are mounted to the fuselage. The 1000 hour check pulls the wings to inspect the wing spar box etc. Flipping the wings upside down on a padded table also allows you to closely inspect the aileron and flap hinge points and replace bushings as needed. Pulling the wings is surprisingly simple - due to the DA-20's roots as a glider.

4. Before starting the engine - turn on your electric boost pump. It will push fuel into the regulated side of your fuel injection system and the fuel pressure gauge should show around 3 PSI for the low setting. For the hi-speed "Prime" setting - it will show even higher. Once you start the engine you likely won't see any impact to your fuel pressure reading as your engine-driven pump will dominate - but you should see some change in your idle RPM. My engine idles too rich when the boost pump is on so the RPM is actually slightly lower - it idles a bit faster without the boost pump on.

In the air, you can turn on the boost pump - go lean of peak with the mixture so the engine RPM goes down just a bit. Now when you turn off the boost pump, your engine will sputter, your heart will stop, but hopefully not your engine, you will go back to full rich, you will curse me - but you will also know that your boost pump was working right up until the time you turned it off...

Maybe I should caveat that last one with a "don't try this at low altitude" - that OPCHECK cannot be found in the manual. It took me forgetting to turn off the boost pump, leaning for LOP - and then noticing the boost pump was left on and I should just go ahead and flip the switch to shut it off...
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Re: 2001 DA-20 C1 questions

Post by Pascal »

YCCA wrote:Hello.. I’m looking for a little help on a few topics.. I just recently bought 2001 DA-20 C1 with an IO-240 overhauled engine and prop with about 90 hours and have a few questions.

1. The oil temp and CHTs are way low. Oil temp only gets to the bottom of the green at high power settings and the CHTs never make it to the green arc

2. What am I looking for when I test the alternate air? I can’t find it anywhere or maybe just missed it.

3. The left wing has some play in it. I found the tolerance in the MX manual but is this normal after 4500 hrs? Mech who just did the 100hr said it was getting close

4. How do I know if the electric fuel pump is working airborne? On the ground I can hear it but when I turn it on the pressure does not move at all.. is this normal?

Thank you for any help you guys can provide... Jeff
Same here. Da20-C1s are known to be running cold. It is really hard for the oil temp to be in the green and the oil pressure in my airplane is usually just above the green in cruise. The oil pressure and temps are in the green only on the hottest summer days in my airplane.

As soon as the temperatures fall below 10C, I plug in the Tanis heater several hours before starting the engine, otherwise it takes ten minutes for the oil temps to go up and the oil pressure to go down enough that I can do the run up check.

In the wintertime, I only gradually descend from altitude while keeping the rpm at around 1900 and regularly bump the rpm for a few seconds. I’m thinking about partially blocking the oil radiator with heating ducts aluminum tape this winter.

I don’t really have a way to tell whether the pump is really working while airborne. I just have it inspected thoroughly at every annual.
As for the wing wiggling, My wings did not move at all when I purchased the airplane and I don’t think I would feel good flying my airplane if the wings didn’t feel well screwed in place. I had the 1000 hours inspection performed last winter since the airframe was reaching 5000 hours. This means removing the wings, the ailerons, and the flaps and inspecting everything. Since all this stuff was already disassembled anyway as part of the inspection, I had my mechanic replace every nut, screw, washer, rubber grummet etc with new ones, sourced from Diamond (these are metric).
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Re: 2001 DA-20 C1 questions

Post by Spinner »

3. I assume that you are referring to the axial play of the B bolt. I would suggest borrowing a digital micrometer and having someone help you measure the play. We usually set the parking brake and then have someone at the wingtip and someone at the wing root to measure the movement. The measurement of movement is to be done above the B-bolt. You will have to peel back the tape along the wing root to this point. The play maxes out at .035 but can be adjusted if it is out of those limits (not easily however).
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YCCA
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Re: 2001 DA-20 C1 questions

Post by YCCA »

Spinner wrote:3. I assume that you are referring to the axial play of the B bolt. I would suggest borrowing a digital micrometer and having someone help you measure the play. We usually set the parking brake and then have someone at the wingtip and someone at the wing root to measure the movement. The measurement of movement is to be done above the B-bolt. You will have to peel back the tape along the wing root to this point. The play maxes out at .035 but can be adjusted if it is out of those limits (not easily however).
Yes what you said, the axial play of the B bolt. The mech who just signed off 100 hr said “it was getting close to tolerance” and would have to pull the wings within the next 100-200 hrs to correct. Of course that was the sellers mech and I can’t help but feel this might have been pencil whipped to avoid the hassle of pulling the wings.. We shall see. Thanks for all the responses
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Re: 2001 DA-20 C1 questions

Post by RMarkSampson »

Just noticed this Service Bulletin that just came out in 2017. Maybe it can help with tracking numbers:
https://www.diamondaircraft.com/wp-cont ... -Rev-4.pdf
From the SB: Availability: Contact Diamond Aircraft Industries Inc
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Re: 2001 DA-20 C1 questions

Post by Pascal »

Mark, thanks for that. If someone on this board has implemented this service bulletin, I would be very interested in any feedback you can provide.
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