TR Failure Drills

[NickLappos]

SASless is right on:

TR stuck at Big power is easier than low power. Reducing the RPM is double magic. The tail thrust drops by the rpm squared, so 90% Nr means the tail rotor is down to 81% of max thrust (.90 x .90). Also, the main rotor torque goes up by the rpm drop, so the torque required to hover goes up by 10%, which means more tail thrust is required to provide the anti-torque. The combination of tail thrust down and main torque up is almost perfect to absorb the max tail rotor angle.

TR at low power, or loss of thrust is different. Whatever you do, start from autorotation and end up in autorotation near touchdown. When the nose swings, and you therefore know thrust is lost or stuck low, get near/into autorotation. That is a safe place to be at, and what you should do when you diagnose the problem. If you can stretch the glide while coming home it might be worth a crack, but do it by slowly adding power from a nice trimmed autorotation. Don't mess around and lose that nose-in-front-of-tail thing, because once you get too slow and have too much right (or left) thrust, your goose is cooked, in a spinning fashion.

How do you try to stretch your glide or fly home with a right thrust situation? from a trimmed auto with a landing spot picked out (your escape route) try raising the collective a little. Keep your feet flat on the floor as all that silly pedal pushing will just frustrate you and allow you to forget the situation (because you will be pushing on them and re-learning what TR failure means). As the nose swings right put in left roll to stop the turn rate, and push the nose down a bit to prevent speed loss. Pick a speed about half way between best climb and best range (maybe 110 knots on a fast helo, 90 in a slow helo). Beedy-eye the speed, do not let it decay! Note speed, ROD and roll angle to keep from turning. As you raise power, you will force more sideslip, needing more roll. It will be screwy, and you will feel very insecure (if you have any brains at all, very insecure). If the nose seems to want to break all the way to the right, just drop the collective a bit to control it. Up collective is right yaw, down is left. With some luck, you can stretch your glide a big bunch. A light weight helo can be flown at a very flay angle of descent if you keep the speed up.

If you halve your ROD, you double your range to touchdown, and you increase the number of landing areas by 4 times (more area to pick one out in). At the bottom, just flare the nose up, drop collective and you will be in auto. Burn off the extra speed to get th best auto speed, then stabilize in the auto and make the landing.

All this fly-home theory is nice, if in doubt, just enter auto at the start, and forget the test pilot stuff, autorotate to a landing. Keep your speed up a bit right till touchdown, as you want the slipstream to help the fin keep the nose behind you.