I've been driving on Chicago roads for 17 years, and summertime around here is always marked by ridiculous amounts of road construction. It seems that every time you turn a corner, another orange construction sign gives you an irritating command. And the delays! Long lines of cars wait to merge into a single lane that isn't going any faster... and don't you hate the drivers that make the problem worse by cruising down the emergency lane and thicken the bottleneck even more?Here's a fun photo of four aircraft lining up for Runway 22L as we turned base for runway 22R today. Pilots don't have an emergency lane that they can use to jockey for a better position. They line up on the taxiway and wait their turn! If only the drivers on the highways would do the same thing... but I digress...
Guess what? Summertime is marked by airport construction, too! Taxiway K is still closed between Y and F, and Taxiway F is closed from Runway 4R all the way back to Taxiway W. As I conducted preflight walkaround of good ol' Cessna 172NT, I looked down F and saw half a dozen trucks with yellow flashing lights zipping around working on the taxiway, kicking up a good amount of dust. Just like the repair trucks on I-94!
A couple irregularities on preflight today. I found a loose screw on the right side of the vertical stabilizer (a.k.a. the plane's tail, shown here to the right). Luckily, the fuel sample cup has a screwdriver attachment, and with a couple turns, the screw was tightened. This is, of course, exactly the reason we do preflight checks. The fuselage undergoes stresses in flight and when landing, and the vibrations alone can be enough to loosen a screw or two. I noticed a second irregularity during the preflight; when I powered on the avionics, and set the altimeter according to the METAR's specifications, the altimeter was reading 560 ft. at ground level. The elevation of Midway Airport is 620 feet, so the altimeter is 60 feet off, which isn't a reason to abort flight, especially because we're a small Cessna flying under VFR, but it isn't a good thing, either! Also noticed just before taxi that the suction gauge was reading outside of the green arc; a little bit high. I asked Tom about these irregularities, and his response, "The readings are a little weird. But it'll be fine."Taxied to the edge of the tower apron, and pulled the throttle out to 1,700 RPMs for run-up checks. I glanced down taxiway F and watched those construction trucks buzzing around. Midway is departing from the 13's today, probably because of the construction. Taxiway F is the only way for us to get to Runway 13R. Tom and I wondered how we were going to get up there... As always, Tower had the solution for us.
"Cessna 172NT, turn right on 4R, turn left to backtaxi on 13R, contact Tower when in position."
Ha! We're using runways as taxiways! At Midway! Weird day.
Taxied into position, contacted Midway Tower. Cleared for takeoff, heading 180. Applied increasing right rudder to counter P-Factor and keep the plane on the centerline. Glanced down at the airspeed indicator, and it showed 40 knots. Just then, the nosegear of the airplane began to shudder.
"Pull back on the control wheel," Tom commanded.
The plane lifted off, and I began a turn to 180. What happened?
"The nose gear was on the ground too long. When you're applying right rudder, you're also turning the nose gear. The shuddering was caused by the friction of the tire turning to the right while the plane rolls straight ahead."
I was waiting for the airspeed indicator to increase to 50-55 knots before rotating, and the shuddering happened at just above 40 knots. Just as I was thinking it, Tom commented, "I think that the airspeed indicator is a little screwy. I'm going to have them look at it."
Chances are that we were rolling at 55 knots even though the airspeed indicator said 40. This can be caused by a blockage in the pitot tube, such as debris or ice. It's 80 degrees today, so I doubt that ice is the culprit, but a tiny bit of dirt in the pitot tube can have significant repercussions. I did look at the pitot tube during pre-flight, and didn't notice anything out of the ordinary, but these strange airspeed indications are a good reason to have the pitot tube checked out.
As I levelled off to cruise altitude, I remembered that the altimeter reading was also a little bit off. These symptoms might be pointing to a blockage in the static port; that's the tiny hole on the side of the fuselage that measures static air pressure, which is used by the instruments to determine airspeed, altitude, and vertical speed. A blockage in the static port can cause all of these instruments to show irregular readings or fail altogether. In a small Cessna such as ours, a failure of these instruments is not as serious as it would be in an aircraft flying under IFR in bad weather, because even in the event of a complete failure of these instruments we will still be flying primarily using visual references. Still, I'll be asking Tom if the problem has been remedied before flying 172NT again.
During today's lesson we will be performing turns around a point and S-turns. Before doing these maneuvers, a pilot must perform "clearing turns", which means that he/she performs a 180-degree turn or 2 90-degree turns to scan the skies for traffic before concentrating on the turns. I am not yet in the habit of doing clearing turns before maneuvers. Tom keeps prompting me by asking, "We're going to do a turn around a point. What do you need to do first?", and I instantly want to answer anything except the answer he's looking for: clearing turns! Safety is paramount when you're a pilot, and performing clearing turns before executing ground reference maneuvers is a very important safety precaution.
All of these maneuvers are conducted at maneuvering speed, which is the highest speed at which full deflection of the controls about any one axis are guaranteed not to overstress the airframe. In this aircraft, maneuvering speed is 97 knots, which is maintained at 2,200-2,300 RPMs. Once we reached maneuvering speed at an altitude of 1,800 feet, Tom asked me to pick an intersection of two country roads down below. The goal is to fly a complete counterclockwise circle around this intersection, tracking a perfect circle over the ground. The wind exerts horizontal force on aircraft, so the pilot must apply varying degrees of bank and stabilizing rudder in order to keep the circle round. For each 90 degree section of the turn, I chose a feature on the ground that was equidistant from the intersection, such as a farm house or a conspicuous line of trees. This process made a lot of sense to me. As long as I kept the sight picture of my reference points and made sure that the plane's arc was wide enough to reach the reference point when the wings were parallel with the road.
Tom quickly quizzed me on how to achieve maneuvering speed in the aircraft.
"Now, what is maneuvering speed in this aircraft?" Tom asked.
"2,200 knots," I responded.
"Wha!?" Tom smiled. "Maneuvering speed is 2,200 knots!?"
OOPS!
"I mean 97 knots, which I can achieve at about 2,200 RPMs!" I corrected myself.
Well, maybe you had to be there, but this was funny! 2,200 knots is 2,200 nautical miles per hour... almost twice as fast as an F-22 fighter jet's maximum speed with thrusters at full! I'll be sure not to say that during my oral exam... such a response is sure to get an eyebrow raise out of my examiner!
Moving on to S-turns. S-turns are similar to turns around a point, but instead of making a circle around a single point, the pilot makes a half circle around the point, then makes a half-circle in the opposite direction around another point further down the same road, to make an "S" over the ground. I was having trouble closing the first half-circle with the wings parallel to the road; in other words, my first circle was too shallow, and my second circle needed to be wider to compensate. On the bright side, I was reasonably good at holding altitude during the maneuvers, although my altitude fluctuations are still outside of tolerances that I will be expected to meet during the checkride. I look forward to continuing to practice S-turns in my next lesson.
With about 30 minutes of lesson time left, we practiced some slow flight and power-off stalls. This is still by far the scariest part of my lessons. Just like practicing stalls, we practice slow flight to get used to how the airplane handles when it is at the very limits of lift. We begin by climbing to 2,800 feet, which is a safe altitude that will permit us to recover from any accidental stall that occurs during slow flight. Our goal is to hold altitude and make shallow turns while the plane is flying just above stall speed. In order to do this, the throttle must be pulled back to 1,600 to slow the plane down (accompanied by activating carburator heat to avoid carburator icing), and I must hold altitude with backward control wheel pressure, setting flaps to 10, 20, 30, and finally 40 degrees. As the stall horn activates, I push the throttle in to around 2,000 RPMs, and the plane will be able to hold altitude at an airspeed of only 40 knots! It's going to take me awhile to feel comfortable when the plane is in slow flight; everything feels wrong! I am deliberately placing the airplane in a configuration which could cause a stall quite easily if I fail to maintain the correct attitude. And the P-factor is so strong in slow flight that I have to depress the rudder very hard just to keep the airplane flying straight, and even then, I'm yawing all over the place. I understand the concept of slow flight, but I'm still very sloppy. I will definitely need more practice in slow flight before I am comfortable with it.
Oh, and on a side note... the stall horn is supposed to sound continuously during slow flight, and this is the moment when another problem with 172NT made itself known. The stall horn would not sound at all. Tom isn't really sure why the stall horn isn't working. There isn't anything electronic in the stall horn... it is simply a reed in the leading part of the wing that makes a whining sound when the wing comes close to exceeding the critical angle of attack that will cause a stall. The best explanation that Tom can come up with is that the reed might simply be so wet that it cannot make a sound. What can we do except be more mindful of our airspeed?
Transitioned from slow flight to power-off stalls. Just like two lessons ago, I would struggle to keep the plane in slow flight, and then pull back all the way on the control wheel until the wing exceeded the critical angle of attack and the wings stalled. The goal is to push forward on the control wheel just enough to reduce the angle of attack and resume normal flight while losing a minimum amount of altitude in the stall recovery. But again, deliberately stalling the plane is very harrowing! During one of these stalls, I felt my heart go straight up into my throat! You know that moment in a roller coaster just when you reach the top of one hill and start to go down another? Same thing here, except in the back of my mind I'm thinking, "There's nothing holding me up!"
Well, I continuously tell myself that the Cessna wants to fly. It wants to recover from the stall. And I can see this in practice because the stall recovery requires very little forward pressure, and the plane begins flying again within a second. Still, stall recovery is another thing I'll have to get used to!
Another lesson is coming to an end, and it's time to head home. Standard approach from the south... and while we were gone, Midway switched to landing 22L and 22R. Tower first instructed us to enter the pattern for runway 22L, but near the end of our downwind, Tower told us to switch to 22R so that he could depart the first of several aircraft waiting to go off from 22L. I had arranged with Tom for him to take the full approach into Midway today, so that I could get this shot of the runway right before we touched down. And of course, Instructor Tom brought her in for a smooth landing, we exited left at F, and I took over the airplane to taxi to the apron. Had plenty of space to park the aircraft this time, and taxied her to the center of the parking space on the first try.Another 2.2 hours in the logbook, totalling 7.9 hours. Continuing to study the Sporty's DVD to review ground reference maneuvers and prepare for cross country flight planning.
Lovin' it.
- Airman Eric
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