Starting Cessna 421 Engines when hot!
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Starting Cessna 421 Engines when hot!
Done anyone have the best way to start the engines on a Cessna 421 when they are warm? They are fine when they have been left to cool for a couple of hours or so, but if you want to shut down, gas and go, it can be a little embarrassing when they take 10 mins to start. I had someone give me one way today involving fuel pumps, mixture and a bit of magic, but does anyone out there know of a recognised way of stating them when warm?
Many thanks
B and Y
Many thanks
B and Y
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I suffered the same problem as you with the warm GTSIO. So much so that I was nearly knocking the battery out.
A Kingair pilot walked over who apparently had a 1000hrs on 421's and showed me this technique which works for me :-
Throttle 1" open
Mixture ICO
Fuel pump Low
Engage starter and bring up the mixture simultaneously.
DO NOT PRIME.
Hope this works for you.
A Kingair pilot walked over who apparently had a 1000hrs on 421's and showed me this technique which works for me :-
Throttle 1" open
Mixture ICO
Fuel pump Low
Engage starter and bring up the mixture simultaneously.
DO NOT PRIME.
Hope this works for you.
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I flew an IO520 powered 206 for many a year in FLA. I had the same problem. I always tried to park into the wind, and open the oil filler and dipstick doors. This helps cool the engine as you fuel. I was told the problem stems from fuel in the injector line vaporizing and not entering the combustion chamber correctly (which sounds reasonable).
And like your first response, the answer is to turn on the fuel pump low, throttle 1" in, and get it cranking, then introduce fuel by pushing in the mixture with a 1-2-3-4 count.
FR
And like your first response, the answer is to turn on the fuel pump low, throttle 1" in, and get it cranking, then introduce fuel by pushing in the mixture with a 1-2-3-4 count.
FR
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I found one of two methods that I would use. Sometimes it would require a stab at both to get them spinning.
1.
No prime, mixture ICO, throttle 1-2 inches open. Either use the fuel pump on low from the beginning, or turn the pump on when the engine starts to take, and then slowly introduce fuel with the mixture control. I found this a little bit of a hit and miss game.
2. (this always worked for me, except for one day....)
Run the prime pumps with mixture ICO and throttle wide open for 20-30 seconds, then stop the pumps.
Then : mixture ICO, throttle fully open. Crank engine.
When it starts to take, bring the throttle back slowly and increase the mixture simultaneously, basically swapping the positions of the levers -
one forward, and one back - slowly!! You will soon find where the mixture lever does its best work with hot starts, and you will see that you dont have to shove it all the way up.
I find that doing that a few times in succession ie. closing and opening throttle and mixture in opposite directions in decreasing amounts, while the engine is trying to tick over, works every time - and as I said, you will quickly find exactly how much mixture she wants once you have mastered this technique, as they all differ and too much can mess up your efforts.
Sometimes you can give it a little extra help with the fuel pump if its really struggling.
Helps if you have three hands.
(I know it sounds a little convoluted - found it quite difficult to describe - but PM me if it doesn't make sense and we can work it out.)
Later
IRP
1.
No prime, mixture ICO, throttle 1-2 inches open. Either use the fuel pump on low from the beginning, or turn the pump on when the engine starts to take, and then slowly introduce fuel with the mixture control. I found this a little bit of a hit and miss game.
2. (this always worked for me, except for one day....)
Run the prime pumps with mixture ICO and throttle wide open for 20-30 seconds, then stop the pumps.
Then : mixture ICO, throttle fully open. Crank engine.
When it starts to take, bring the throttle back slowly and increase the mixture simultaneously, basically swapping the positions of the levers -
one forward, and one back - slowly!! You will soon find where the mixture lever does its best work with hot starts, and you will see that you dont have to shove it all the way up.
I find that doing that a few times in succession ie. closing and opening throttle and mixture in opposite directions in decreasing amounts, while the engine is trying to tick over, works every time - and as I said, you will quickly find exactly how much mixture she wants once you have mastered this technique, as they all differ and too much can mess up your efforts.
Sometimes you can give it a little extra help with the fuel pump if its really struggling.
Helps if you have three hands.
(I know it sounds a little convoluted - found it quite difficult to describe - but PM me if it doesn't make sense and we can work it out.)
Later
IRP
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Hot starts on Cessna 421 B engines.
I flew them for many a long year and no real troubles in starting them when hot.
Used to flood the engine, then idle cut-off, throttle set about an inch or so, then crank. When the fuel mixture reached the starting ratio, the engine would commence to start, then idle cut-off gradually up to normal and away you would go.
It worked for me.
Tmb
Used to flood the engine, then idle cut-off, throttle set about an inch or so, then crank. When the fuel mixture reached the starting ratio, the engine would commence to start, then idle cut-off gradually up to normal and away you would go.
It worked for me.
Tmb
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Thanks everyone. The ICO and use of fuel pump method that you have described was pretty much what we used yesterday, although it was a bit rushed so it never quite sunk in what was going on. Seeing it in writing gives me a good idea of what needs doing, so I will use that method next time to avoid the worry of running the battery down and getting stuck somewhere! Thanks again.
B and Y
B and Y
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Going into the POH, dated 1 Nov 1979 it does actually say: 'Engine mis-starts.......is more apt to develop in hot weather or when the engines are hot. If it occurs, repeat the starting procedure with the throttle approximately 1/2 open, the mixture in ICO and the Primer Switch off. As the engine fires, move the mixture control to full rich and close the throttle to ide.'
So it is similar to the advice above, but I think that the use of the fuel pumos and the techniques in previous posts are going to be more successful - we will see!
So it is similar to the advice above, but I think that the use of the fuel pumos and the techniques in previous posts are going to be more successful - we will see!
B&Y
If you are from where your profile states I suggest you drop into the hangar at Connington. I believe the guys in there have experience of looking after the 421.
Otherwise PM me if you would like to chat about your a/c.
MM
If you are from where your profile states I suggest you drop into the hangar at Connington. I believe the guys in there have experience of looking after the 421.
Otherwise PM me if you would like to chat about your a/c.
MM
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Have heaps of time behind IO520s' in both singles and twins. The problem with hot starts on fuel injected engines is that the fuel in the injector lines vaporises due to the heat of the engine so that when you start there is mostly air instead of fuel being injected. The problems would occur with hot starts after the aircraft had been shut down for about half an hour.
Starting prior to that I would not prime the engine, may occasionally require a touch of boost pump but more importantly not going full rich on the mixtures. Most engines are set to run very rich and I found this would often flood the engine when it had just started.
After half an hour and up to an hour I would leave the mixtures in ICO and the throttles closed and run the boost pumps for up to a minute. This had the effect of putting cold fuel through the lines up to the fuel metering unit. Once you have cold fuel in the lines, prime the engines as per normal then start. Note this can only be done on Continental engines which have the return fuel line from the metering unit to the tanks. Do not do this on a Lycoming.
Starting prior to that I would not prime the engine, may occasionally require a touch of boost pump but more importantly not going full rich on the mixtures. Most engines are set to run very rich and I found this would often flood the engine when it had just started.
After half an hour and up to an hour I would leave the mixtures in ICO and the throttles closed and run the boost pumps for up to a minute. This had the effect of putting cold fuel through the lines up to the fuel metering unit. Once you have cold fuel in the lines, prime the engines as per normal then start. Note this can only be done on Continental engines which have the return fuel line from the metering unit to the tanks. Do not do this on a Lycoming.
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I agree, it can be a pain to start the engines when hot. It was the one thing I disliked on my 421. My own technique was idle cut off, pump on 30 seconds, pump off, advance mixture to fully rich and close to ICO rapidly (no more than two seconds for complete cycle). Throttle two inches open. Start cranking with starter, engine would fire within 20 seconds, when it starts to fire - smoothly advance mixture to fully rich (approx 2 - 3 seconds from ICO to full rich). Set throttle to 1200 and then do other side.
In over 400 hours of flying the 421, that hot start technique never failed. It did take me a few hours in the early days to find the correct technique though!!!
In over 400 hours of flying the 421, that hot start technique never failed. It did take me a few hours in the early days to find the correct technique though!!!
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I also endorse the "fuel purge" technique (which many of the above include variations of). The feature that makes all these combinations succeed is running the pumps with the mixture at cut-off for long enough to put cooler fuel into the pipes. I suspect that some of the other steps are voodoo, but once you have purged the vapour from the pipes, whatever works for you... will work.
