AS-350 B2 Power Assurance Check
Does the AS-350 B2 power assurance chart give you fits? I’m just back from the Eurocopter factory and while sneaking a glance over the shoulder of an engineer I jotted down the equations for the B2 power assurance check. Here they are, very simple and tidy and suitable for insertion into a spreadsheet. It's also far easier than attempting to weave a pencil through those confusing charts. Use at your own risk.
'inputs
fat -30 to +50 [outside air temperature]
pa 0 to 12000 [pressure altitude]
Q 50% to 94% [observed torque]
Nr 380 to 400 [observed rotor rpm]
Ng 91% to 98% [observed Ng]
theta = (fat + 273.16)/288.16
delta = (1.0 - (pa*0.001981/288.16))^5.256
Ng = Ng/(theta^0.475)
if SAND_FILTER_INSTALLED
kW1 = -0.4916*Ng^2 + 118.90*Ng - 6504.6
else
kW1 = -0.5240*Ng^2 + 126.83*Ng - 6939.0
kW1 = kW1*SQRT(theta)
kW1 = kW1*delta^.9733
kW2 = 0.12376*Q*Nr
if (kW1 < kW2) then
PASS
else
FAIL