I am the co-owner of a 2004 model DA-40-180 with 40 gallon tanks, looking to have the MTOW increase kit installed. With a small wife and daughter, I don't run into problems with MTOW often, but it would be nice to have the flexibility.
My partner has no need for the upgrade so I will need to make a case for it. I could use some advice from those who have gone before me:
- Is there any way to determine the value add to the airplane in $$? To me the kit seems like a bargain for 100lb capacity increase, but I haven't been very convincing.
- From someone who has flown both before and after the upgrade, did the flight characteristics change at all? Many of the V speeds move ~1-5 kts in the wrong direction.
- Can someone explain what the kit actually does? I assumed it changed/increased the range of motion of the elevator, but I don't see how that alone would change something like Vx/Vy and best glide range.
MTOW Increase OSB kit 40-057/2
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- Diamond_Dan
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Re: MTOW Increase OSB kit 40-057/2
I had this done a couple of years ago. There are two related kits.
The pricey one is the increase in MLW, which requires changing out the main gear for slightly thinner, more flexible ones. It requires that the plane be reweighed. It has the side effect of trimming about 3 lb. off empty weight. This allows MLW of 2535 lb, an increase of 128 lb.
The second limits up-elevator travel and is fairly inexpensive. This raises MTOW to 2646 lb. It requires that the MLW modification has been done. so there is this dependency.
The stall speeds don't change unless you fly it heavier. The maneuvering speed does increase in a particular range, but this is actually a good thing. Weight affects the speed at which max glide is achieved. It doesn't change the actual glide angle. This is something sailplane pilots use to their advantage on cross-country tasks.
The pricey one is the increase in MLW, which requires changing out the main gear for slightly thinner, more flexible ones. It requires that the plane be reweighed. It has the side effect of trimming about 3 lb. off empty weight. This allows MLW of 2535 lb, an increase of 128 lb.
The second limits up-elevator travel and is fairly inexpensive. This raises MTOW to 2646 lb. It requires that the MLW modification has been done. so there is this dependency.
The stall speeds don't change unless you fly it heavier. The maneuvering speed does increase in a particular range, but this is actually a good thing. Weight affects the speed at which max glide is achieved. It doesn't change the actual glide angle. This is something sailplane pilots use to their advantage on cross-country tasks.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
- Rich
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Re: MTOW Increase OSB kit 40-057/2
BTW, we've been through this exercise before, but it's likely you already have the proper main landing gear. If so, your max landing weight somewhere should be listed at 2535. So you would just need the elevator limiter gizmo installed.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
- Diamond_Dan
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Re: MTOW Increase OSB kit 40-057/2
Thank you Rich - very helpful.
Please help me understand how limiting up-elevator travel will allow me to take off with more weight. I think I am missing something.
I am still very interested in the $$ proposition cost/value if anybody can help me rationalize it.
Please help me understand how limiting up-elevator travel will allow me to take off with more weight. I think I am missing something.
I am still very interested in the $$ proposition cost/value if anybody can help me rationalize it.
- Rich
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Re: MTOW Increase OSB kit 40-057/2
It's to allow you to FLY with more weight.Diamond_Dan wrote: Please help me understand how limiting up-elevator travel will allow me to take off with more weight. I think I am missing something.
Basically, stall-resistance is partly accomplished by limiting how much of an angle-of-attack you can produce. Many planes, from Ercoupes, through Cherokees, and including the Diamonds have elevator travel limited so that you can't easily get into a deep stall. In the worst scenario, that extra weight is rearward, and substitutes for more powerful elevator command. So Diamond further limits the elevator travel to compensate for the most rearward CG condition at the higher weight.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5