Saturday, September 18, 2004

Instrument Lesson 6

Today's lesson was fairly uneventful. This was the first sunny day in weeks...of course, when you are taking instrument flight lessons, you kind of hope for clouds. Not today. Not a cloud in sight.

Most of my time lately has been spent in N6033H, but that plane is down for its annual inspection - maybe they'll replace the vacuum pump and/or the heading indicator. The vacuum has been reading consistently around 4.6" Hg, which is slightly below the 5" that the POH calls for. The POH even says that operation below 5" will cause the vacuum gauges to perform erratically. That would seem to describe the behavior of the H.I., since it seems to precess considerably compared to the H.I.s in the other two Warriors. The attitude indicator also has a very slight wobble and tends to indicate a slight left bank in level flight and on level ground. Perhaps that is also due to low vacuum.

With 25 year old aircraft, there are bound to be some quirks, but none of the Warriors have ever let me down - pardon the pun.

So, today I was scheduled to fly N84577, a slightly newer plane by one or two years, but it appears to have many more hours than the other Warriors. This one also has air conditioning (but it is inoperable) as well as an autopilot (also inoperable) and a GPS (with an outdated database). None of these flaws really matter, though. The only problem is that with the autopilot servos still in place, the trim wheel is significantly more difficult to adjust than that of the two planes without an AP. The turn coordinator seems to be more sensitive than in the other planes, though. very slight banks tend to send it off kilter, so maintaining a standard rate turn in mild turbulence is challenging - I can only imagine how hard it would be in rough weather.

Today's lesson included full and partial panel stalls - power on, power off, and power on with turns. It has been quite a while since I did any stalls, but I managed to handle them just fine. We also did full and partial panel recoveries from unusual attitudes. There are two basic procedures for recoveries from unusual attitudes. In each, the first step is to determine the attitude of the aircraft - nose high or nose low. The second step is always to adjust power. If nose low, power is reduced; if nose high, power is increased. The next step for nose low is to level the wings followed by up elevator to return to level flight. For nose high, you first push the nose down, then level the wings. The two things you are trying to avoid are 1. Exceeding the structural limits of the aircraft which can happen if speed is allowed to become excessive. 2. Stalling and/or spinning the aircraft which can happen if speed drops too low or angle of attack is too great.

In the first test today, the plane was turned over to me, but there was no apparent change in airspeed. Changing airspeed is the first indication of attitude, so I had to wait a second and noticed the sound of the engine - the rpms sounded like they were diminshing which would also indicate a nose high attitude. Recovery in this case was very easy since all I really needed to do was increase power slightly and level the wings.

The next few tries, Justin really shook up the plane - thought I'd lose my breakfast for a minute although that has never happened before. On all of them, I recovered according to procedure.

We also practiced partial panel turns to headings using the compass as well as timed turns. Turning to the East or West is easy - just initiate a standard rate turn until E or W shows up in the compass and you'll roll out on the right heading. Turns to northerly or southerly directions are more of a pain. For North, you have to roll out 30 degrees early and for South, you have to roll out 30 degrees late. In every case, it takes a bit for the compass to stabilize although it seems to stabilize better to the East and West. You also have trouble with errors caused by acceleration or deceleration. At any heading other than North or South, accelerating will cause a more northerly indication and decelerating will cause a more southerly indication. I really blew a turn to 120 degrees. Justin was announcing our position and when he does that his hand presses on his yoke and that usually causes the nose to drop a bit. Today, I think he really liked hearing himself talk because his calls took much longer than usual. Anyway, I noticed that I had lost too much altitude - about 150 feet which is not to standard, and I immediately pulled the nose up while I was turning. With no AI and no HI to refer to, I was left with the turn coordinator and the magnetic compass. As soon as I started to climb, the compass began to spin, We decelerated and I was already turning towards the south, so that just made the compass turn faster. I eventually leveled off and turned back to 120.

Returning to the airport, Justin gave me vectors to steer. We were initially given clearance to fly straight in for runway 32 - which would have given me an opportunity to fly the localizer, but about 3 miles out, the tower told us to enter the left base for 23. So much for the localizer. Then as I descended, Justin asked for a soft field landing. I was on a stable descent, so this was going to be easy - and it was. I nudged the throttle just before touchdown to make it as smooth as possible and then let the plane glide until touchdown. I held the front wheel off the ground as long as possible, but then had to break pretty hard to make the turnoff at Bravo-4. That meant the landing took under about 1800 feet, so that wasn't too bad.

Not a bad day - 1.2 total time and the quick runup and takeoff gave me 1.1 of simulated instrument.

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