Just Flight PA-28 Arrow underpowered?

[CopperNu]

@TCPD5091

Where are you reading the TAS number? If it is on the iPad, I believe that TAS number to be wrong. the OAT probe is displaying ISA not OAT. Whatever the OAT is, add 15C to it and use that new temp and set the altitude over the new temp on the airspeed indicator. See what TAS you get on the white band on the bottom of the airspeed indicator. I was using it yesterday and was getting 142 knots TAS at 11,000 feet. Try that and let us know what speed you’re getting. Screenshots are nice, too!

I compared the data and found that the EFB showing the same TAS as LittleNavMap and it is the same as GS if you set weather without wind.

From what I understand is that the OAT gauge is wrong but also the scale of the pressure altitude on the IAS gauge - I think they are both off by the same 15°C and thus result in a consistent TAS readout (which would be the reason that testers didn’t spot this issue).
So if you read out the OAT gauge and dial in this temperature in the IAS gauge, you end up having the same TAS as shown on EFB and in LittleNavMap.

142kts at 11.000 sounds a bit too high for me (I’d expect 138 or so at best power cruise) and I guess the above is the reason.