MOSAIC and PA28-181 Stall Speeds?
Exciting news yesterday from Oshkos - the MOSAIC final rule allows Sport Pilots to fly aircraft with clean stall speeds up to 59 KCAS, up from the proposed 54 KCAS, which includes a lot more PA28s.
My question is: what is that speed for my PA28-181 Archer II? Looking at the POH (manual VB-1120), you can read it a number of ways. Reading the stall speed KCAS straight off Figure 5-5, it looks like 59.3 KCAS. Does that round to 59 KCAS? (the final rule isn't 59.0). If you read the KIAS and then convert it using figure 5-3, I get less than 58 KCAS. So which is it? I've asked Piper for clarification via their web site, will see if I get anything back.
Comments
In knowing enough about how things get written (and not having seen the actual narrative), based on "...clean stall speeds up to 59 KCAS..." might likely have an interpretation that rounding down from 59.3 to 59 is not allowable. Put another way, the speed will probably need to equal something less than (but not equal to, or greater than) 59 knots.
I have seen scuttlebutt where the FAA put a lot of good work into letting MOSAIC help the industry. But at the same time, words have meaning and it is best to get clarification direct from the source.
With that, am curious as to whether it is allowable to factor the effect of aftermarket vortex generators on the official tables and new 59 KCAS stall speed. If so, this has the potential to open the slate of Sport Pilot eligible planes even wider.
I cannot imagine the 0.3 on the chart is going to make a difference since the line width itself is a good portion of that! See if this data from the POH section 2 matches your POH:
Looks like 59 KCAS is what Piper considers "Normal Operating Range." Also, from another source of general definitions:
"VS1 is where the white arc meets the green arc, or is commonly referred to as the bottom of green arc, or the power-off stalling speed with gear and flaps up."
Looks like your good.
Regards,
Mike