DA40 Maximum Landing Mass
Someone recently attracted my attention to an interesting part of the DA40 aircraft flight manual: the maximal landing mass. Large airplanes (business jets and airliners) often have can’t land at the maximum take-off weight, because of landing gear structural constraints. If the landing has to be anticipated, the crew must dump or burn fuel, to get the weight within limits (read this post on fuel-dumping).
This is restriction is quite common on large aircrafts, but I’ve never seen it on a single engine plane before. The AFM defines the maximum landing mass as “The highest mass for landing conditions at the maximum descent velocity. This velocity was used in the strength calculations to determine the landing gear loads during a particularly hard landing.”
To talk numbers, the maximum take-off weight is 2535 lbs, and the maximum landing mass is 2407 lbs, 128 lbs lighter. This difference represents 19 US gallons of Jet-A1, or 3 hours of flying at cruise power ! The DA40 has no fuel dumping mechanism.
An “Overweight landing procedure” is defined in the “abnormal procedures” section of the AFM. It consists only in an increase of approach speed. Normal approach speed with a weight of 2407 lbs is 67 knots, and it must be increased to 71 knots for a weight of 2535 lbs. The AFM says no more – specifically, it makes no mention of what has to be done after an overweight landing.
A look at the aircraft maintenance manual do not help. The “hard landing check” procedure is defined, but its sole trigger is when the pilot declares a hard landing. It does not even mentions the maximum landing mass.
The question which arise from these findings is to know how legal it is to fly, in examples, circuits at maximum take-off weight, or take-off with three persons on board, fly for one hour, and land. If any landing above maximum landing mass means inspection by a mechanic, operating the DA40 would require such inspections after most flights…
If any expert wants to comment, this will help making things clearer to me…
3 Comments, Comment or Ping
Jess Sightler
I have no idea as to the answer to your question.
Having said that, I have also only seen this on one aircraft that I have flown. In my case, it was the AMD Alarus, which also has a lower landing weight due to a gross weight increase that did not increase the landing weight.
Anyway, it is an interesting question and I hope someone knows a good answer.
Mar 21st, 2008
Hani
Yes, this was a major disappointment to me when I learnt this (our club recently acquired a DA40). I mean it’s one thing to have a maximum landing weight below max takeoff weight, but when the delta represents 3 hours of flying, this is a pretty significant setback, in my humble opinion. (Full tank give 5 hours of flying, if my figures are right). With passengers and luggage, this means you can’t land with more than 2 hours of fuel! Not exactly “security inducive”!
Apr 24th, 2008
PlasticPilot
Hani, I don’t know which rules the club will define, but other club (LSGL) and school (LFMD) where I operated were all doing basic training (circuits and short flights) with full fuel and sometimes PAXs.
I did not found up to now a rule saying it’s forbidden to land a DA40 at more than MLM. There is this procedure for extra-weight (a bit of extra speed) but that’s it.
I will follow that closely with who you know…
Apr 24th, 2008
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