Points for Pilots

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...

Access hole to tail cone: 14 in. tall, 17 in. wide During the past 20 years, our Zenith 601HDS, N314LB, has flown 1,725 hrs, all with the original Rotax 912 engine.  During the most recent annual, we checked the tail cone as usual, using a bright light and scanning everything. It all seemed okay, until we suddenly noticed tiny cracks in the L-shaped stiffeners of the bottom plate that were hard to see from the cockpit. Crack in stiffener Almost every stiffener had cracked at least once! Quite a shock, but in hindsight not so surprising. The outside of the bottom plate experiences positive pressure during climbs and negative pressure in cruise. Thus, the skin is flexing time and again. Of course, a better design would have used a curved bottom part, which avoids the flexing problem altogether. The easiest fix seemed riveting new L-shaped stiffeners to the old ones so that they together formed a U channel. Our friend Jack not only gave us the right material, .032 in. Al...