CFI: Kristie H.
Aircraft: Robinson R22 Beta II
Aircraft ID: N8361N
Duration: 0.8hrs
Cumulative Time: 15.8hrs
Best session to date. Well, eventually.
Things started out rather messy. 61N was to be used, the previous night, for an aerial photography session. As such it had the left door and left controls removed to allow for a passenger with a stack of cameras to move freely about. Apparently they also were planning a significant flight since the tanks were maxed out on fuel.
So, it spend the night out in the open, no door in the freezing cold. The windows were covered in condensation and everything needed warmed up before we could start. During the oil check I found that we were a little low and I had to go get some to get back to the school's 5 quart minimum. Line service had not had a chance to replenish the engine oil stash so I had to walk all over the place to find bottles with any oil in them.
Line service is responsible for general maintenance on the aircraft and they are the ones you are supposed to call for any fuel issues. So, I called them and asked to have fuel taken out (as I'm only allowed to fly with 16 gallons. They want to get people flying as fast as possible and filling takes priority. So we had to wait.
Once we had everything checked out and were ready to go we tried to start 61N. No go. Nothing. Starter would turn over, but the engine would not catch. Clearly it was because it spent the night in the cold, wet air. After the 6th try we got it rolling.
Once we got into Charlie pattern we ran a few laps and each one was spot on. I really think the key to it was recognizing ETL... both for take off and for landing. The only way to describe it is that you want to keep in the sweet spot... and that happens to be ETL. You can tell because of the slight vibrations felt through the helicopter. It is very slight at the beginning, builds to a max, and then trails off.
It was easiest for me to Imagine a bell curve. As you approach ETL you start getting small vibrations. You know you are headed the right way or doing the right thing when they build little by little. You want to stick to the green section and ride the vibrations all the way in/out. If you end up doing the wrong thing or don't act fast enough you will end up out of the green.
Ride the vibe all the way and you are good to go. One thing to note is that the helicopter also tells you when you are doing something very wrong with vibrations as well. I'm told they are not little or slight... but really hardcore and bone wrenching. As I said... it is all about feel.
1 comment:
The ETL shudder is very important on a landing. At some point you will make a tailwind landing because of a gust or shear and you'll feel the shudder prematurely when you still have lots of ground speed.
In any landing, it's also a last wakeup call to check the VSI to make sure you're not setting yourself up for a settling with power scenario.
Any time there is a change in vibration level or frequency, the helicopter is trying to tell you something. It may be benign like ETL or like some ship will vibrate at certain air speeds. It may also signal an incipient retreating blade stall or something else. So even a mild, but unexpected, shudder or vibration is trying to warn you of something.
Not all violent vibrations are catastrophic either. I read an account of a Robbing shaking violently. The pilot got it on the ground and discovered that the "never pull down" decal had peeled back about 1/2". That small event caused the rotor T&B to change enough to cause the shake!
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