Page 24 - Nov23

have even allowed their idle Np to drop below the limit. If this has happened, simply move the condition levers forward enough to get the necessary propeller speed.
Second, make your final condition lever adjustments to match propeller speed, Np, not compressor speed, N1. By doing so, the airplane sounds better – less out-of-sync drumming – and tends to track straighter while taxiing. Requiring a 1 or 2% split in N1 speeds to match Np speeds is common. If much more than that is required, it indicates that the maintenance shop needs to do a better job of setting the propellers’ low pitch stops to the correct and same, left and right blade angle.
The third comment concerning the use of the heater on the ground is to remember that certain, more important, in-flight users of electricity take priority over the comfort provided by heater operation. These “heater lock-out” items are windshield heat, prop deice and engine lip boot heat, if installed. The pitot cowls fitted to the C90A and after models use exhaust gases to heat the inlet lip, but previous C90s, B90s and A90s – as well as 100s, A100s and F90s – use an electric heating boot on the cowling inlet lip.
“The vast majority of King Airs now use bleed air as their source of incoming cabin air and supplement ... with an electric heater of some type.”
22 • KING AIR MAGAZINE
NOVEMBER 2023