Points for Pilots

Tallahassee, FL Class C airspace. Our southbound route is depicted by the green line. A recent trip from Texas to Sarasota, FL proved once more the value of ADS-B when we faced bad weather en route. In our plane, the ADS-B information is displayed by the Garmin Pilot on our iPad . The app obtains the relevant information via Bluetooth from the onboard GDL39. The latter unit receives the ADS-B data broadcast by ground stations as well as by other aircraft. But the trip also showed that the information may become corrupted when other iPad apps are invoked in flight, without a hint that things have gone wrong. Here are the details. We take off from the Marianna, FL airport early in the morning. Shortly thereafter we transit the outer ring of the Class C airspace of the Tallahassee airport. That ring demands flight to be below 1400 ft. Selecting an altitude of 1200 ft MSL, we satisfy that condition; see the green route in the above screenshot. As we near the Gulf Coast of Florida...

Rotax 912 engine: upper coolant elbow with flange, cylinder #3. The liquid seen on the bolts is Corrosion X added after installation. By 2017, our Rotax 912 engine had run 1,815 hrs over 22 years.  During that time, the engine always had some small loss of coolant on long trips, as was evident from a slightly lowered coolant level in the overflow bottle.  We attributed the change to evaporation.  So during each oil change, we added a bit of coolant to that bottle.  In recent years, the level in the overflow bottle dropped somewhat more rapidly, and we had to add coolant after each extended cross country tip. We could not see any obvious leaks:  The water pump did not show any leaking coolant in the bleed hole or at its four elbows, all hose connections were dry, and the upper and lower coolant elbows of the cylinder heads showed no loss of coolant. Coolant elbow at bottom of cylinder #1 Then came a surprising change.  We had flown from Ae...

Flight plan with GPS waypoints When we fly a complicated route over rugged and sparsely populated terrain, we would like to file a flight plan that tells the exact route. Unfortunately, today's format of flight plans was formulated in the olden age of Telex communication, where each character was considered an expensive item to transmit. As a result, there is no way to tell the flight service precisely where we are going, even if we add some description of the route in the remarks section. Come the modern way of defining and storing routes to the rescue. In our case, we use the Garmin Pilot, where the route can be graphically modified and then displayed with GPS coordinates for each waypoint.  We use that information as follows. First, we file the regular flight plan, with limited information as constrained by the current form.  We include the phone number of a contact person who will monitor our flight. That is, upon landing at the destination, we have agreed to cal...

Typical windy afternoon at Hale County in Plainview, TX . Toward the end of a commercial flight, the captain always announces, "Flight attendants, prepare for landing." We need to do that, too, when we fly our little planes.  Should be easy, shouldn't it. Well, things can become difficult, as we shall see in two cases. The first one we handled poorly, but the second one, well.  Let's go back to captain Chesley Sullenberger, who landed an Airbus A320 with both engines out on the Hudson River and thus saved all lives. We learned later that he had the habit of regularly checking destination weather, regardless how far away.  It seemed a splendid idea, and we have gotten into the habit of doing that every 30 minutes. It has turned out to be an excellent idea. On to the first story. We are flying from Aero Country, our home base, to Plainview, TX. The main destination runway is being repaired, but the alternate runway has ample length.  While enroute, we...

Red bug at 55 kts is Vref marker During every biennial review, we must demonstrate recovery from a stall. But as J. Mac McClellan writes in the June, 2016, issue of Sport Aviation,  that process evidently has not helped reduce the number of fatal stall/spin accidents.  He compares the practicing of stalls for general-aviation pilots with the ironclad rule of the airlines according to which airspeed may not go below Vref, defined as 1.3 times the stall speed. No wonder the airlines have virtually no stall/spin accidents! So why not adopt this same rule for our small planes? One may argue that this cannot be done since Vref depends on the configuration of the aircraft and payload. But there is a conservative approximation where we take max weight and consider the stall speed without flaps and with flaps in landing configuration. In each case, the stall speed is multiplied by 1.3 and the resulting value is marked on the airspeed indicator. This produces one mark for enr...

Pressure sender installation The Rotax 912/914 engines store engine oil in a separate tank. The oil pump sucks the oil out of the tank and pushes it into the engine.  Blowby p ressure in the crankcase then returns the oil from the engine sump to the tank.  Oil pressure and temperature are measured at the oil pump, to be displayed on the cockpit instruments.  What can possibly go wrong, and how can failures be diagnosed? This post addresses that question. Oil Level During preflight, the propeller is repeatedly pulled through until a burping sound coming from the opened oil tank indicates that engine blowby has pushed all oil in the engine sump back into the tank.  At that time, the dipstick of the tank correctly indicates the oil level. If a hot engine was stopped for an extended period, say at least 12 hours, then typically 10 or more blades must be pulled through before the burping sound occurs.  Pull the blades slowly so that the compress...