Chieftan Engine Start

[boofhead]

In cold weather it seems the mighty Chieftan is a tad hard to start. My boss thinks that if the engine has to be started twice or if it coughs the passengers will lose confidence in the pilot. He has a point but I have seen even the most experienced pilots have trouble occasionally.
The book says six seconds of prime with throttle half inch and that used to work for me, but at this company the Maint Mgr wants 3 seconds with the throttle full open.
Seems the same to me but what do I know.
If it works it works great but if it does not start on first rotation you just know it is going to try its best to make you look a fool, and I don't need help to prove that.
If the temps are below freezing it is easy to over prime but if not enough prime it fires but will not run. A fine balance that is hard to achieve knowing the boss is looking down from his window. If you don't get her running within a few minutes of pulling the airplane out of the hangar you might not get her running at all.
The hangar is not too warm and I think that is part of the problem. the airplanes do not have engine heaters.
Some days the temps are -15 or -20C and the minimum allowed is -35C. In those conditions in the field we use engine covers during turn around, which work great. I will start her up every two hours or so to keep everything warm. A warm engine is not a problem. Always starts immediately then.
I thought I had it skun the other day but after the three seconds I forgot to pull the throttle back to idle before starting and when it started it got rich real quick, with a little backfire before I could get it evened out. Most embarrassing.
The only thing that saved me from a roasting was that another pilot could not get his engine started at all so they concentrated on him, but I know they will not forget me next time. No sense of humour at all.
But if anyone has tips or tricks that work, please pass them on.

[Tee Emm]

Ask any Chieftain pilot for his advice on how to start a Chieftain engine in various weather conditions and you will find all will have a different personal technique. So you have to think outside the square.

Firstly, what does the POH say about engine starting?

Secondly, seek the advice of the pilot that pays your wages. Then use his technique:ok:

[ironbutt57]

but at this company the Maint Mgr wants 3 seconds with the throttle full open.

Then have the maint mgr start the engines..the pilot is responsible to follow all approved procedures...so have the maint mgr publish his ideas as an approved procedure....on that note....I flew those for five years, and used the the following technique..

1 Throttle full forward
2 Boost pump on
3 Mixture advanced to full forward and back to idle cut-off over a count of 5 sec
4 Boost pump off
5 Throtttle back to 1/2 inch forward of idle
6 Crank the engine, at first firing advance the mixture to full rich quickly
7 After the engine stabilises, lean mixture slightly and allow eng to warm up with cowl flaps closed at 1000 rpm

[Gulfstreamaviator]

I used same procedure.

2500 hrs on type.

BUT

When "hot" always actually very difficult.

[Tinstaafl]

I operate a PA31. Only difference between hot & cold starts for me is throttle full open & a short prime for hot, and throttle cracked & a longer prime for cold. I can't recall the last time I didn't have 1st time start.

[boofhead]

What's the theory on those two cases? Why throttle open on one and closed on the other? When cranking, do you have the throttle closed all the way or cracked a bit? If it does not immediately fire, what do you do; give it more prime or let it die and start again?

[Big Pistons Forever]

7 After the engine stabilises, lean mixture slightly and allow eng to warm up with cowl flaps closed at 1000 rpm

The POH specifies that the cowl flaps be full open for all ground ops........

[sevenstrokeroll]

why not get there early, run the engines for a few minutes with no one around and then come up to the loading area.

we did that at an airline that used similiar engines in a different type of plane.

[Tinstaafl]

Because when cold it starts very quickly. When hot a short prime tends to make it way too rich to startl so quickly. Cranking with the throttle fully open expedites reaching a combustable mixture which reduces cranking time to close to the cold start time.

[Checkboard]

Temperatures -15ºC to -20ºC?? :confused: Where in the Pacific ARE you? :ooh:

[boofhead]

North Pacific. Alaska.

[fantom]

Never mind all that; how about we spell it correctly?

Chieftain.

[boofhead]

Yep, you are right. Chieftain. Maybe that is what is causing the problem; the airplane is insulted.

It is also a lot warmer here this week, around +3C which is shirtsleeves weather and the airplanes love it too.

I operate many types of piston engine here, from round engines to Rotax, and the Chieftain engine is the only one that gives me grief. I can usually prime the heck out of a cold engine and it will start, but not this one. It seems to be very critical to having just the right amount of fuel. Too little and it will not fire, or will only cough. Too much and it will not start.

I would love to find a reliable priming or throttle setting to guarantee a smooth start and keep the boss happy.

[Yankee Whisky]

Once a working procedure is found, stick to it ! Although I have flown with the Continental O470-11 (updraft carb) the book procedure calls for primer injection and that seems to cause hung starts quite often.(100LL,87 and Mogas)
I found out that using the throttle acceleration pump once or three times (depending on temp) starts the engine at first crank. Cranking must be immediately after the last throttle pumping action to prevent a carb intake fire. It helps if the ignition is also "ON" as I have seen many pilots forget to switch them on when cranking an engine ! That, and setting the mixture at full rich !:ok:

[boofhead]

I did not think this engine had a throttle pump?
It certainly does not have a carburetor.
Would there be a difference in elec pump output, maybe putting more fuel in one engine than planned? It seems to be the right engine on both of our airplanes that fail to start most.
I want to have a procedure that all the pilots can use, and the one we use now is not fool proof.
The pilots start the engines as soon as the airplane is pulled out from the hangar, but the hangar is not very warm. The engines seem warm enough but we don't wait too long before starting them, then we warm them up to about 50 deg oil temp and shut down to refuel. Finally load the passengers and start again with the engines still warm.
Normally works just fine but occasionally it does not and then the pilot gets the hot seat because it is assumed that it is operator error and so far I have not been able to find a reason why this is not so.
The passengers are not impressed either, even if the OAT is below -20C and the wind is 20 knots right down the throat of the engine.
Some of the most experienced pilots fail to get a good start sometimes, and if the throttle/mixture is not just right, there is also a period after start before the engine finds its rhythm.
Not a big deal in the greater scheme of things but it causes grief.

[TSIO540]

I've operated Pa-31's down to about -5C. We used to set throttles full open, mixture rich, pumps on for about 3 seconds (or as required to get about one second of fuel pressure indication), then mixture ICO, throttles cracked til you hear the switch click (about half an inch), mags on, crank until it fires... then rich... (One at a time)

Occasionally after start the engines would struggle to accelerate much past 800-900 rpm with an indicated manifold pressure of 20" which does not respond to throttle movement because the mixture was too rich... So a little bit of mixture leaning smoothed it out and rpm stabilised with a drop in manifold pressure to a more normal <10" approx.

The POH requirement for cowls open on the ground was explained to me as being there to prevent hot spots around engine seals and rubber pipes.

[Uplinker]

As a slight aside, I am always amazed that in these days of most new cars being available with fuel injection and sophisticated engine management systems - meaning that they always start first turn of the key in any weather; That aircraft piston engines are still using carburetors, primers, mixture controls, carb icing controls, booster pumps etc. etc. all operated manually by the poor sweating/freezing pilot!

Obviously, aircraft engines require more redundancy than a car's single system, but that would not be difficult to arrange.

[hawker750]

If you think starting a TSIO540 is tricky try a TSIO720 on a hot day, best have a couple of spare starter motors and 3 or 4 spare batteries!

[Oakape]

While I never operated in such cold temps, I found that after a couple of start attempts you never knew quite where you were.

After a couple of start attempts I used to just flood the thing so I knew where I was. Mixture full rich & 5 seconds minimum on the boost pumps. Then throttle wide open & mixture cut-off. When she fires, close the throttle & then advance the mixture.

Good luck!

[Tinstaafl]

That's pretty much my technique for any warm or hot start.