It could be a number of things.
1. Different test pilot getting the test points for a very subjective test point.
2. Different rotor blades, possibly a difference in abraision strips from C20B testing to C20R2 testing.
3. A less smooth track on the acft that set the C20R2 test points.
4. Rougher air when they flew the C20R2 test points.
Originally Posted by
Hot and Hi
Could somebody explain why the VNE is differs between the two engines, for the same type?
For example, at >2,500 lbs, 30 deg C OAT, and a pressure ALT of 6,000' the VNE for the 500D equipped with a B engine is 103 KTS. With the (more powerful) R/2 engine it is 96 KTS.
On the 500E the respective VNE's are: 102 KTS (B engine) vs 96 KTS (R/2 engine).
(Source: VNE placards from the MD Rotorcraft Flights Manuals: 500D revision 9; 500E revision 14)