The perfect start

There are a few times when pilots become especially self-conscious about being observed by others: when talking on the radio, when landing, and when starting the engine. Of the three, as I’ve written before, starting a piston engine is by far the worst — you shout “CLEAR!” to make sure everyone on the crowded apron is watching, then deliver a loud commentary on your progress (or lack thereof) with a loud CHUFF-CHUFF-CHUFF-CHUFF. If it goes on too long, people start either to stare at you, or even worse, to look away in embarassment. Eventually, if the engine doesn’t fire, you stop for a while to let things cool down, then repeat the whole humiliating process. At this point, a well-meaning instructor or mechanic might take pity on you and walk over to give you a hand, before both your battery and your ego run completely flat.

Hot starts can always be tricky, especially with fuel-injected engines, but winter starts have their own sets of problems. This winter, however, I’m happy to report that my newly-overhauled engine has started on the first try every time, within 1-4 seconds of hitting the starter. I’ve been leaving my Tanis heater plugged in, so that the whole engine is uniformly heated whenever I want to fly. When I’m at a remote airport for a couple of hours, I keep my priorities straight, by putting the insulated cover over the cowl to hold in the heat before I put my own coat on.

A different starting technique

I’ve also been using a different starting technique. My first AME showed this to me a few years ago, but I didn’t fully understand it at the time; since then several other pilots have mentioned it on mailing lists (note that this applies to carbureted engines; it will be slightly different for fuel-injected:

  1. open the throttle all the way
  2. close the mixture to idle cutoff
  3. prime a few times (see below)
  4. crank the engine
  5. as soon as the engine fires, pull the throttle down to close to idle and push the mixture to full rich at the same time

There is no fixed rule for how many times to prime — it depends on how warm the engine is, how your primer works, and how many cylinders have primer lines connected to them (since each squirt will be divided among all the cylinders). In my Warrior, with three of four cylinders connected to the primer, I typically prime 3-4 times for a cold start and 1-2 times for a hot start. Flooding isn’t a big risk, since there’s no fuel flowing to the engine at first beyond what you supply manually with the primer.

My plane also has a reasonably new starter and copper (rather than aluminum) electrical wiring, both of which are important for starting. My battery is near its last legs, and I should replace it soon to make sure my luck holds up.


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4 Responses to The perfect start

  1. Paul Tomblin says:

    That’s very similar to the starting technique I was taught for our fuel-injected Lance – you leave the throttle, prop and mixture exactly where you found it when you get into the plane (ok, you might advance the mixture to prime and then bring it back to idle-cutoff). Crank, and when it catches advance the mixture. So far it’s worked first time, every time, hot or cold. Supposedly starting fuel injected engines while hot is a bit of a black art, but I’ve never had a problem with this method.

    (BTW: You have an empty <li></li> pair in your mark up which is making your numbered list screw up.)

  2. david says:

    Thanks, Paul — I’ve fixed the numbering.

    I suspect that most of the time, the problem with starting is too little or too much fuel. If I’m right, then this technique works well because it lets you start with a small, measured amount of fuel in the cylinders with no additional flow — if there’s too much at first, it will drain down over the next few seconds until you have the right fuel-air mixture, since no new fuel is coming in.

  3. John says:

    Here’s another priming approach that works well for tempermental, fuel-injected engines (like the IO-550N in the Cirrus SR22). Prime the engine in the manner called for by the check list. Then wait three to five minutes. Record the ATIS, call clearance delivery, whatever … Then start in the normal fashion.

    In my experience, most starting problems come from too much fuel. Then if the engine is reluctant to start, most pilots do something that puts even more fuel into the equation. I’ve found that minimal priming has always been the most successful approach. Or switch to a turbine engine … 😉

  4. Jim Howard says:

    I’ve found that the IO-360 in my Cardinal starts when cold every time when I follow the checklist, which is prime with fuel pump to 5-6gph, mixture full lean, throttle cracked.

    If I know I’m going to do a hot start I make sure to shut down by running the engine to 1200 rpm and pull the mixture. Then when I start it by up I just turn the key without touching a thing. As soon as it starts to fire ease in the mixture. Works every time. This is the recommended procedure by the Cardinal Flyers Orgainization.

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