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Reply To: Diamond

Malmin Ilmailukerho ry Forums Keskustelu Diamond Reply To: Diamond

Miika Asunta

The following is not supposed to be a sermon, and certainly not training material, but I feel I have to write this. I am not an instructor, just a hobbypilot usually listening to what more experienced pilots have to say. I am going to a point out few differences I have found between these aircraft during the self-studying of first days of my summer holiday. I’m new to DA40 TDI so please point out if I’m missing something. I just checked I have flown 19 hours with OH-KAS, there are certainly over 200 hours in OH-SRH. As I wrote earlier, I haven’t flown OH-DDS. Now I regret I haven’t done so.

The airframe is the same in KAS, DDS and STL.

The engine is practically the same in STL, and DDS, as well as in SRH. There may be some difference how propeller is controlled by the Thielert computer between C172 and DA40, eg. how the propeller slows down the plane when power lever setting is reduced.

The fuel system of STL requires special attention. It’s a completely different design from what we have learned in KAS. Main tank and auxiliary tank, with a electric fuel transfer pump and a mechanical emergency fuel valve. Warm fuel returning via pipeline inside both tanks to the main tank, warming up cold fuel.

STL has also a fuel cooling system to be used if ground air temperature is above +20 C to avoid excessive heat in the auxiliary tank. An external mechanical baffle is to be removed from an air intake below right wing. The baffle should be inserted if ground temperature is below +20 C. This is operated by pilot before flight, and is this mentioned in any published checklist? AFM preflight checklist mentions this. We even have the little yellow baffle somewhere in the cockpit. I wondered what it is when I first saw it.

The loading and mass&balance are very different in STL, DDS and SRH.

STL: MTOM and Max landing mass 1150 kg, empty weight 843 kg.

DDS: MTOM 1150kg, but max landing mass only 1092 kg, empty weight 810 kg (hopefully I have current data)

KAS: MTOM 1200kg, max landing mass 1200kg, empty weight 798 kg

STL has an extra permanently installed 5 kg weight in the rear to help with forward CG balance issues experienced in DDS.

These three planes will be different during approach and flare, even if CG is within the limits: STL can be 58 kg heavier than DDS, and KAS can be loaded much heavier than these two.

This implies that if we fly a heavier aircraft, the result of a hard landing will be more dramatic. If we are in a too high landing flare – a typical result of gusting wind – and we have a somewhat exaggerated nose-up attitude, the loss of lift is likely to happen suddenly, accompanied with a tail strike. DA40 will just stop flying. For an average Cessna pilot this will be a surprise, but it will also surprise a DA20 pilot. And if the plane is lighter, it fill fly longer. But how long?

We have two DA40 aircraft in the Malmi hangar without wheel fairings installed. These are usually not used during winter, but in a hard landing these are likely to break first.

I think hard landings can be avoided with training. It is not just bad luck if there’s a hard landing. It is not just bad luck if I forget the tow bar. Accidents are not just bad luck.

How many people and how much fuel you can take? If you can do something at one airplane, it doesn’t mean you can do it in another similar looking plane. OK, every one of us knows this and every pilot it the world knows it because it was taught during the PPL course, and as we have the licence, we know what to do. But without an interactive mass&balance spreadsheet or webpage or other tool, how many of us would do the calculations manually?

Climb performance will be different in these planes. STL will not be a rocket climber like KAS.

Accidents can happen, yes. We have insurance policy, yes. But an insurance does not guarantee the next pilot has an intact plane with clean wings washed from mosquitos and other insects after nice smooth summer evening flight, with a clean unscratched canopy.

We want to keep our planes flying. Of course, in a critical situation human life is more valuable than a plane. But this is not my point here.

Our plane just looks so nice in hangar, that I would like to fly it like that. I bet you want the same!

Aihe: .