Increased takeoff and landing weight

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BlueYonder
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Increased takeoff and landing weight

Post by BlueYonder »

I'm plugging W&B numbers into Foreflight for my 2007 XL. Among the options offered for the plane that year were an increased takeoff weight, and an increased landing weight. Both put the total weight at 1200kg, or 2646lbs.

My POH has documentation showing that the increased takeoff weight modification was made and certified. But there's no equivalent page showing that the increased landing weight mod happened, too. Which, if true, gives this a ridiculously big difference in W&B profile between takeoff and landing.

So here's my question: Did Diamond do this -- upgrade the takeoff weight but not the landing weight? (Seems like a very weird thing to do.) Or is it likely that I'm just missing a page in my POH? And how do I find out what the real story is?

It's a huge difference in the actual useful capacity of my plane, so I'd like to get the right numbers plugged in.
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Colin
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Re: Increased takeoff and landing weight

Post by Colin »

Is there a logbook entry for the work done to increase the takeoff weight? It will correspond to a document that will answer that question.

(From what I remember from talking to the factory people at an AOPA fly-in, the limiting factor is the landing gear. It has to be able to withstand being dropped from 15' fully loaded. Since I always fly at least two hours before landing, I am always under that limit, even if I might be close to the limit on take off. And if the plane is heavy it is usually filled with things I care a lot about, so those landings are super careful, not dropping from even three feet.)
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BlueYonder
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Re: Increased takeoff and landing weight

Post by BlueYonder »

I'm digging in the airframe logs, and found a list of service bulletins listing the specific alterations made to this plane at the time it left the factory. (In terms of documentation, it probably doesn't get better than this.)

Nothing specific about extended landing weights, but there are a few items on the list to do with the gear that might be pertinent:

-- Optional aluminum gear axles
-- Main landing gear struts, smaller main landing gear tires
-- Installation of taller main landing gear

Think this is the kind of stuff that a beefed-up landing gear system might include?
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blsewardjr
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Re: Increased takeoff and landing weight

Post by blsewardjr »

Sara- I thought I knew the technical answer to your question but an examination of the Optional Services Bulletins does not yield a clear answer. The increase in TAKEOFF weight is actually the result of a modification to the elevator which can be done pursuant to OSB 40-057/2. HOWEVER, for this modification to be made, the aircraft must have one of two new versions of the main gear added. It is these main gears that provide for the increase in the LANDING weight. As noted in the OSB, the purpose of the elevator mod is:

"To provide the elevator travel required for take-off mass increase to 1200 kg (2646 lb).
Note: The higher 1200 kg (2646 lb) take-off mass is only approved when 18 mm main
landing gear struts (MÄM 40-123 or OSB 40-025, latest effective issue) or the taller
main landing gear struts (OÄM 40-283 or OSB 40-059, latest effective issue) are
installed on the airplane."

The older OSB, 40-025, states that installation of the new main gear "increases of [sic] the maximum landing mass to 1150kg (2535 lbs)." However, the newer OSB, 40-059, does not have a similar statement. Since you have the smaller wheels, you likely have the taller main gear installed under OSB 40-059. (The taller main gear offsets the smaller wheel and thus restores the correct aircraft attitude on the ground.) As stated in that bulletin, the purpose is:

"To improve ground attitude of airplanes with 15x6.00- 6 main landing gear tires and aft
empty weight center of gravity. Compatible with 1200 kg (2646 lb) take off mass
(OSB - 40 - 057)."

That said, its my understanding that all DA40s with the taller landing gear have a LANDING weight of 2535 lbs. I just can't find it documented in the service bulletins.
Bernie Seward, IR, AGI
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Re: Increased takeoff and landing weight

Post by CFIDave »

The maximum takeoff mass for the Lycoming DA40-180 (1200 kg) is more than its maximum landing mass.
See page 8 of Diamond's official checklist:
http://support.diamond-air.at/fileadmin ... _17_A4.pdf

If you takeoff at max gross weight, either fly around and burn off fuel before landing, or be careful when you land not to "drop it in."
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Re: Increased takeoff and landing weight

Post by BlueYonder »

This forum's depth of knowledge never ceases to amaze me. Thanks for the rundown on the actual modifications required for the 1200kg increase. It looks like I'm covered on both ends, despite only having the paperwork in the file for the takeoff weight increase. Barring any superceding info, I'll enter my landing weight at 2535lbs.

And Dave, thanks -- I did figure that out. The original numbers I was using were something closer to a 200lb difference between the two weights, and I kept thinking: that can't be right. And apparently, it's not.
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Rich
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Re: Increased takeoff and landing weight

Post by Rich »

Sara,
Is it possible that the plane was delivered with the necessary gear and only needed the elevator limit OSB? If the gear was replaced after delivery that should have been entered in the aircraft logs also, as it is work done on the plane. And removing/replacing the gear ain't no small thing (and requires reweighing the A/C), so it would be sloppy record-keeping.

Having had my plane for its entire life from the factory, I have the full history of the evolution of the changes in W/B over the years. Do you have the original W/B report for the plane? It'd show the original max landing weight as either 2407 lbs. or 2535.
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Re: Increased takeoff and landing weight

Post by BlueYonder »

Rich, that would make perfect sense. The original equipment list shows the tall nose gear, so it would follow that the only mod required would be the elevator limit change. And the max landing on the original 2007 cert is, in fact, 2535. QED
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