Points for Pilots

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...