I am posting the following in the interest of removing porpoises. Posted at Kevin’s suggestion.
You are correct in your understanding that Wings Aloft now suggests an approach speed of 75 kts in the SR20. Our newly-revised checklist reflects
that. Actually, we did it to match the Cirrus SR20 Pilot Operating Handbook, which suggests 75 knots for both a normal landing and a short-field landing.
This is the only significant content change that was made in the revised checklist - other changes were for editing or clarity, addition of some
metric units for our international customers, and a couple of rearrangements to match more common procedures. Therefore, we believe it just isn’t
significant enough to replace any pages.
To explain the approach speed change: When we originally learned how to fly the SR20 in 1998 and 1999, the Cirrus pilots of the time showed us that the plane is more controllable at 80 knots final approach rather than at 75.
Certainly there is the disadvantage of a longer landing distance, but most of the time that is not a problem, and when the runway is short we use the short field technique and 75 knots. However, while 80 knots is more controllable for approach, we have discovered in the last few months that if a pilot tries to plant the plane on the runway before enough airspeed has
bled off, the plane can bounce substantially, and many less experienced pilots end up porpoising over the runway. This is especially likely if the
plane is nose heavy (forward CG), which can happen in the SR20.
If the approach is flown at 75 knots, the roundout and flare requires more finesse on the part of the pilot: the plane is closer to stall, so it must be in just the right attitude at just the right altitude above the runway in a very short time. The end result is usually a firmer landing than at the higher approach speed. However, it is true that the plane is less likely to bounce in such a way that a porpoise ensues.
And to add one more factor, we find that the landing behavior of the SR20 is affected by landing weight, so a landing at 80 knots at max gross weight is actually very similar to a landing at 75 knots with one person on board and
not much fuel.
In other words, the pilot needs to decide. For consistency with Cirrus, we have put the POH-specified airspeeds in the checklist, and then during flight training we show the pilots how the plane behaves at the different approach speeds so they can make their own choices.
I hope this makes things clearer - if not, please send me any more questions
you may have!
Cirrus Training Manager
Wings Aloft, Inc.