Plane & Pilot
Tuesday, June 4, 2013

Hot Starts


Fuel injection is a wonderful feature—most of the time. In hot-weather restarts, however…


Obviously, you can't expect to have much success with hot starts unless the airplane's ignition system is in optimum condition. That means plugs properly gaped, shower of sparks or impulse coupling working correctly and battery well-charged. Engine design doesn't help much in that fuel metering at low idle speeds is often poor to terrible. That's one reason some engines tend to lope and miss at idle.

I used to have consistent hot-start problems in my Mooney until a clever mechanic concluded my shower of sparks was only barely working. He replaced the unit and, voilà, problem solved.

As mentioned above, every airplane/ engine combination will have its own hot-start procedure, but there are a few general rules for managing hot starts. The comment above by the Phoenix pilot may work for you. Leave the throttle and mixture in the shutdown position, turn on the pump and hit the starter. This will sometimes prompt the engine to fire, if it has only been shut down for a few minutes. When it does start to kick, slowly advance the mixture. You may need to leave the pump running for quite a while to keep everything turning.

Another technique that sometimes works if your first try isn't successful is the Max Conrad method. Conrad used to tell me this worked for him every time, no matter what the temperature, humidity, pressure, wind, stock market condition or your personal biorhythms. Push the throttle and mixture full forward, and turn on the pump for a good 20 seconds.

Conrad used to say, "This is almost guaranteed to create a flooded-start situation. Now you have a known condition. Pull the mixture to idle cutoff, leave the throttle against the forward stop and crank." Conrad said when the cylinders begin to vote on running, slowly retard the throttle and advance the mixture to "catch" the start.

Whatever technique you use, remember never to run the starter longer than 30 seconds and allow several minutes between attempts to let the starter cool. Also, remember to cease and desist altogether before you grind the battery down to nothing. The worst consequence of a hot start that goes bad is that you may have to wait until things cool down. Better to have some battery left for later, when you can start the engine normally.

Hot starts are a fact of life if you plan to realize maximum utility from your airplane. Learn the best method of using them, and you very well may be able to avoid the madness.



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