PLT027: Rotor Blade Coning
What code PLT027 covers, why the FAA tests it, and how to study Rotor Blade Coning before your checkride.
Define coning
What this means for your checkride
Coning is the upward bend of the rotor blades that occurs when lift and centrifugal force act on them at the same time. On the ground with the disk unloaded the blades stay nearly flat, but as lift builds during takeoff the blades assume a conical path instead of staying perpendicular to the mast. Centrifugal force pulls the blades outward and gives them rigidity, so the faster the rotation, the smaller the coning angle. If rotor rpm is allowed to drop too low, centrifugal force decreases and the coning angle becomes much larger.
Coning ties directly to rotor rpm management, and understanding it explains why low rpm and heavy loading are dangerous.
Pilots may think coning is a defect or overload sign, when it is a normal result of lift and centrifugal force acting together.
Where to study it
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.