13 Jul Autorotation Entry
Various emergencies, regardless of type, start with the entry to an autorotation. Popular terminology used in the POH’s are: land immediately (which are often taught with autorotation), enter autorotation, or apply autorotation procedure.
They are one of the most frequently practiced maneuvers during flight training. To prepare the students for a true engine failure the instructor would typically, after checks are done, countdown and then roll the throttle off. The student must then learn to react correctly and establish the helicopter in a balanced autorotation. The big problem that the student faces is that the sequence of events are almost always preceded with the feeling in your left hand of the throttle being closed – particularly in helicopters with twist grip throttles. Whether we practice autorotations or engine failures, we roll the throttle off to make controlling RRPM obvious.
At this point you may ask: “So what’s the problem?”
Our left hand has now built in muscle memory to close the throttle when the collective is lowered while our brains are in autorotation mode. We are doing too few power-on autorotations during our flight training. I have seen too many times pilots close the throttle of a serviceable helicopter while they wanted to/needed to land in a hurry. I have watched CPL pilots going through the motions in their minds before a test, rolling the imaginary throttle close on autoration entry – maybe not such a good idea.
Bearing in mind that throttle and engine RPM maintenance is often the instructors problem during emergency practice and the average PPL and sometimes CPL has never really worried about engine RPM control before. This extra burdon and workload during an already potentially stressful situation now keeps your eyes in the cockpit and leads to making bad decisions on the way down. Even flying into something becomes a very real possibility.
So there are 2 problems as a result:
1. The students react almost purely on a feeling of the throttle being rolled closed in their hand and not on the loss of power symptoms.
2. Because rolling off throttle is so practiced as being part and parcel of the procedure we do it without thinking or realising.
My interpretation of “ENTER AUTOROTATION” means to lower collective to the point just before the RRPM wants to start overspeeding. If the POH wants you to roll throttle off it will specifically say so. A power-on autorotation means you can pull collective at any time you change your mind with less workload on the way down.
In my opinion this can be practiced in 2 ways:
Autorotation procedure practice – Always lead with collective fully down then roll throttle off to eliminate the engine in order to practice RRPM control. The student should do everything, including throttle work.
Engine or drive-train failure practice – The throttle could be rolled off by the instructor to simulate the failure and the response procedure is then practiced by the student excluding throttle work. This way we don’t mix things up in our minds and increase our situational awareness.
– Philip Merrick