This morning the winds were from 050 at 9kts. So runway 7L and 7R were in operation. This meant a long taxi from our hangar and a good time to lean the mixture. Carburetors are calibrated to properly mix fuel with air at sea level. During normal engine operation, a proper air-fuel mixture is fully burned in the engine for optimal performance. When the engine runs at a low RPM (for instance while taxiing), the rich air-fuel mixture isn’t fully burned due to a cooler engine. This causes carbon buildup in the spark plugs and the fouling can result in lower engine performance. The carbon buildup can also occur if the mixture is too rich e.g. at higher altitudes where the air density is lower but unadjusted fuel density remains higher. For better engine performance, less likelihood of spark plugs fouling up and to warm the engine sooner, leaning the mixture is recommended when a long taxi is anticipated.
We start off by performing power-off stall recovery in the clean configuration. I was very slow in powering up the engine to recover from stalls and as a result dropped over 500′ on the first couple of attempts attempt. After many tries, ended up with between 50′-75′ of altitude loss.
Then Steve demonstrated a power-on stall with 2200 rpm on the engine i.e. not fully powered up. Power-on stalls typically occur during takeoff or a go-around. Listen for the stall horn and drop the nose. Steve demonstrated a tendency to spin to the left if the stall is not recognized quickly. If that happens, the first thing to do is to pull back the power and relax the back pressure to increase air speed over the wings to produce lift. Then power up and pull back.
Next was engine out simulation. First trim for a glide speed of 65kts. Then run through a checklist
- Was the fuel selector accidentally kicked around or is the selector still on both?
- Is the mixture rich?
- Is the carburetor heat off?
- Check the throttle
- Check mag switch positions and whether that revives the engine
- Check the primer if it is IN i.e. off.
Once the usual suspects have been eliminated, observe the wind and look for a place to land into the wind. Brown fields better than green (wet). Smooth fields better than plowed fields. If plowed, along the furrows better than across. No railroad tracks. Since we identified a place to land and it was pretty much beneath us, we had to lose altitude quickly. One could either perform 360 turns to lose altitude. Or, in this case Steve demonstrated a forward slip.
Time for a ground reference maneuver – turns around a point. It is important to enter the maneuver downwind and maintain about 800′ AGL. On the first orbit observe the effects of the wind and remember mental landmarks where the turns should occur. Subsequent turns are expected to be more accurate. At one point, Steve suddenly took over controls and performed an evasive action by banking the plane to the right. This was upon spotting another plane in the vicinity. Then back to the ground reference maneuver this time turns to the right.
Finally, time for some touch-and-go’s at Byron. Steve talking on the radio for each leg of the approach to Byron is quite informative. The first landing was pretty hard, second was good and the third was below average.
On the way back to Livermore, we had a close call with a Skycatcher coming towards us. Tower told us that the Skycatcher was 3 miles out at 2000′ and we were at 3100′. A couple of minutes later, the tower informed the Skycatcher (which was now at 2400′) that an inbound Cessna was 1.5 miles in front and suggested that he turn right. As I was commenting to Steve that 3100′ was about our altitude, he gestured me to turn right. While I was trying to process the information, the tower asked us to turn right because of the Skycatcher and Steve jumped on it right away to avoid the oncoming aircraft.
