Reply-To: "Dudley Henriques" From: "Dudley Henriques" Newsgroups: rec.aviation.student Subject: Why We Don't Pull Mixture!!! Organization: International Fighter Pilots Fellowship Message-ID: Date: Sat, 27 Jan 2001 14:55:27 GMT Keep in mind ladies and gents, that it's not my intention to start a war about this subject. Some of you have had positive experiences in dealing with this issue, and that's good. Every experience, whether positive or negative should be a learning experience in an airplane. We all agree on that! What we would like to do is keep those negative examples to a minimum, since the overall goal is to remain in one piece after the lesson is over. Now, why is it unnecessary to pull mixture to idle cutoff in a single engine airplane to demonstrate to a student that the glide characteristics will be changed with the propeller stopped? Let's deal with this one question, because when it comes right down to it, it's this that seems to be causing some confusion. It's not written in stone how an individual instructor is allowed to demonstrate a particular maneuver or aspect of flight training to a student. The powers that be have decided long ago that if left alone, most CFI's will naturally find the best solution as it relates to their individual teaching methods. The fuzz concentrates on the finished product of that teaching during the flight test. The examiner pulls the throttle for either a high or a low altitude emergency; then watches as the applicant either solves the problem that's presented, or screws it up. Either way, it's the result that is judged. In teaching students forced landings and in-flight emergencies, most of us who have been doing it for awhile have learned that the statistics involving simulated emergencies turning into actual emergencies are eye opening to say the least. Fortunately, in teaching emergencies, it just so happens that the optimum method for doing this coincides with improving the stats. If you examine the plus and minus sides of this issue you begin with the goal; that being to impart on the student the knowledge and skill required to react properly and perform properly in an emergency situation; in this case, an engine failure. Pulling the mixture to idle cutoff is viewed by some as beneficial in two areas. 1. Presenting the student with a sudden, startling problem so that he/she can obtain experience with the "shock" that always accompanies a total engine failure. 2. A demonstration to the student of the different glide characteristics between a windmilling propeller and a stopped propeller. Now, on the surface this appears to be a worthy goal, but let's go a bit deeper into the problem; examining it more closely. What's the down side on pulling the mixture to idle cutoff? 1. Shock cooling 2. Broken mixture cable 3. Fuel related problems on restart 4. Broken starter 5 Unforeseen engine component failure that denies restart ....and on an actual dead engine approach followed to landing.....errors in judgement resulting from any mistake....the inability to solve a problem presented at touchdown by incursion or obstruction. Now, let's take this and put it in perspective. Does the risk justify the means? The answer is an emphatic NO!!! The reasons for this were discovered years ago, and here they are. 1.Pilot shock during total engine failure will occur regardless of a prior demonstration. The proper way to reduce it's impact is through a careful presentation to the student, given on a continuing basis; stressing that it should be EXPECTED, and dealt with as the first item on the emergency checklist.[ i.e..shock felt...shock expected...shock gone...handle emergency!] This process with proper training can be reduced to seconds. Without proper training it's worthless to induce pilot shock. The result is usually a brain freeze followed by confusion and over tasking. In general, just yanking the mixture to idle cutoff is considered bad instructional reasoning. 2. The windmilling propeller problem as opposed to the stopped propeller. It goes without saying that a stopped prop will change the glide ratio. To kill the engine to demonstrate this is not necessary; and for this reason. Assuming a high altitude engine failure that has been determined as unsolvable through normal checklist procedures,regardless of the glide ratio,[stopped or windmilling] after the airplane has been stabilized at max glide, the completion of the forced landing is accomplished by VISUAL CUES. This means that REGARDLESS of the glide ratio presented by the prop condition, the pilot should be reacting to what the AIRPLANE IS TELLING HIM/HER at ANY SPECIFIC INSTANT IN TIME. I can't stress this enough. Forget the graphs and charts. You should already know that the glide ratio is less with a windmilling propeller. Expect that! Your only concern should be placing the airplane at a chosen key position at the right altitude. With the airplane stabilized at max glide, the sink rate becomes a constant. What you have to do is choose the correct angle of bank to produce the turn required to put you where you want to be....period! The bottom line on all this is simply that if taught correctly, a student pilot and the airplane need not be subjected to the risks stated above in order to learn proper emergency procedures. Most of us in the instruction community don't pull mixture and cut switches for the reasons I have given here. Granted, you will find those who believe yanking mixture and cutting switches is good practice. It's up to each pilot out there to find out for themselves what is correct and not correct. I strongly suggest that before you decide which is the right approach to this problem, you seek out competent FAA opinion on the matter. -- Dudley A. Henriques International Fighter Pilots Fellowship Commercial Pilot/CFI/Retired