Engine starting problems
Joined: Feb 2006
Aviation Qualifications: LAME
Posts: 1,129
Likes: 168
From: Station 42
Easy when you know how. 
I've heard some horror stories about running the battery down in the middle of nowhere because a hot injected engine wouldn't start. Someone told me he was once reduced to throwing a bucket of water over the engine to cool it down...
I've heard some horror stories about running the battery down in the middle of nowhere because a hot injected engine wouldn't start. Someone told me he was once reduced to throwing a bucket of water over the engine to cool it down...
Joined: Sep 2007
Posts: 31
Likes: 0
From: Iceland
Just wait till you start flying aircraft with fuel-injected engines: It is some kind of a black art: many have tried, few have mastered. Sometimes it just seems that moving the throttle/mixture in some random order works best 
Thread Starter
Joined: Feb 2006
Posts: 352
Likes: 0
From: Daventry
Car engines
I can't understand why they don't start as easily as car engines,they are very similar in many ways,must be mainly down to having mags.Pity they don't have coil ignition just for starting.
You don't have to think about different techniques for starting different brands of car.
MM
You don't have to think about different techniques for starting different brands of car.
MM
Joined: Jun 2003
Posts: 13,787
Likes: 0
From: EuroGA.org
If an engine doesn't start using the POH procedure, get it serviced!
The fuel servo may be knackered and needs an overhaul.
For example, my engine - while starting as per the book every time - used to really shudder on shutdown. Nobody thought it was abnormal. However, when it recently went to the USA for the SB569 crank swap, the firm noticed this and said it wasn't right, and they found a leak in some fuel control valve in the fuel servo; it wasn't closing properly and some fuel was getting through, preventing a clean shutdown. Now it's fine. But nobody in the UK would have noticed this.
That fuel servo would not have been looked at until overhaul @ 2000hrs which for most private pilots is "never". And even then I doubt the usual UK engine shop would have noticed anything.
The thing which also helps hugely is the installation of the new Skytec lightweight starter. I got the latest NL model fitted. This is a lot more efficient because the permanent magnet has been replaced with a wound magnet; it rotates the engine several times faster than the stock starter, making cold starts instant and hot starts sorted within 2-3 seconds.
The fuel servo may be knackered and needs an overhaul.
For example, my engine - while starting as per the book every time - used to really shudder on shutdown. Nobody thought it was abnormal. However, when it recently went to the USA for the SB569 crank swap, the firm noticed this and said it wasn't right, and they found a leak in some fuel control valve in the fuel servo; it wasn't closing properly and some fuel was getting through, preventing a clean shutdown. Now it's fine. But nobody in the UK would have noticed this.
That fuel servo would not have been looked at until overhaul @ 2000hrs which for most private pilots is "never". And even then I doubt the usual UK engine shop would have noticed anything.
The thing which also helps hugely is the installation of the new Skytec lightweight starter. I got the latest NL model fitted. This is a lot more efficient because the permanent magnet has been replaced with a wound magnet; it rotates the engine several times faster than the stock starter, making cold starts instant and hot starts sorted within 2-3 seconds.
Joined: Apr 2008
Posts: 1,086
Likes: 36
From: France
None of you guys have to swing the prop, do you? Believe me, if you do you soon learn what your engine needs. Arms wear out much faster than starter motors.....
We did have an interesting one on our cub. 150 horse lyc, with a starter motor. Zero time engine and mags, got progressively harder to start, hot or cold. Found out it was the spark generator for the shower of sparks mags that was dying. Apparently this isn't considered part of the
engine.
The engine would actually start, which was probably some sort of miracle.
After several hours scrabbling around at the back of the firewall managed to replace the buzzer (which still _sounded_ like it was doing its stuff). Now we are back to starting on second blade.
For interest.....
Cold start pull the prop through 12 blades
Four strokes of primer
pull through 12 more blades
get in
mixture rich
switch on power to starter motor ( the separate switch is to allow a hand swing with the shower of sparks mags)
pump throttle twice then closed
both mags on (on key)
engage starter motor
when the engine fires gently advance throttle
check oil pressure etc....
Hot start
mixture rich
switch on power to starter motor
Pump throttle twice
throttle closed
mags on both
engage starter motor
etc....
The same engine in other aircraft usually has impulse mags, which are cheaper and easier to find. Most 150 cubs have no primer, and all the priming is on the throttle, with the mags on switches. We have a lot of little configuration oddities, probably due to the aircraft being a conversion from a 135, done in holland by the navy.
Used to fly a taylorcraft which would regularly catch fire on start. The prop swinger would wear a cap for this reason, which nicely covered the air intake to starve the flames. Saved filling the enging with gunge from an extinguisher. Interesting aircraft, combined all the worst points of the auster and the cub and none of their good points, but it was cheap to hire, which helped pay for the wear and tear on headgear. Still, at least the designer was capable of learning from his mistakes
We did have an interesting one on our cub. 150 horse lyc, with a starter motor. Zero time engine and mags, got progressively harder to start, hot or cold. Found out it was the spark generator for the shower of sparks mags that was dying. Apparently this isn't considered part of the
engine. The engine would actually start, which was probably some sort of miracle.
After several hours scrabbling around at the back of the firewall managed to replace the buzzer (which still _sounded_ like it was doing its stuff). Now we are back to starting on second blade.
For interest.....
Cold start pull the prop through 12 blades
Four strokes of primer
pull through 12 more blades
get in
mixture rich
switch on power to starter motor ( the separate switch is to allow a hand swing with the shower of sparks mags)
pump throttle twice then closed
both mags on (on key)
engage starter motor
when the engine fires gently advance throttle
check oil pressure etc....
Hot start
mixture rich
switch on power to starter motor
Pump throttle twice
throttle closed
mags on both
engage starter motor
etc....
The same engine in other aircraft usually has impulse mags, which are cheaper and easier to find. Most 150 cubs have no primer, and all the priming is on the throttle, with the mags on switches. We have a lot of little configuration oddities, probably due to the aircraft being a conversion from a 135, done in holland by the navy.
Used to fly a taylorcraft which would regularly catch fire on start. The prop swinger would wear a cap for this reason, which nicely covered the air intake to starve the flames. Saved filling the enging with gunge from an extinguisher. Interesting aircraft, combined all the worst points of the auster and the cub and none of their good points, but it was cheap to hire, which helped pay for the wear and tear on headgear. Still, at least the designer was capable of learning from his mistakes
Joined: Jan 1999
Posts: 6,209
Likes: 2
From: north of barlu
IO450
I have had reliability issues with light weight starters, I doubt that this will be a problem that you will have due to the low engine start to engine hours ratio that you run as a private owner.
However those of you that have more than one engine start per 45 min of engine time may well want to think very hard before fitting a light weight starter.
However those of you that have more than one engine start per 45 min of engine time may well want to think very hard before fitting a light weight starter.
Joined: Jun 2003
Posts: 13,787
Likes: 0
From: EuroGA.org
True A&C, my 1st one burnt out after 2 weeks. Mind you, it was (not a Skytec) a 2001 stock which had never seen a drop of oil. It was an AOG job and I got ripped off £1000 - the real price is about $450.
The Skytec starters come in different versions. The original 'lightweight' one draws a huge current - see that URL I posted. The NL version draws much less.
The Skytec starters come in different versions. The original 'lightweight' one draws a huge current - see that URL I posted. The NL version draws much less.
Joined: Nov 2003
Posts: 636
Likes: 0
From: notts
Prime concerns
Going back to the simple normally aspirated systems.
When using the primer should the cylinder be flooded the fuel will run back into the hot air box just as it may using the throttle to prime.
There is no difference in that respect therefore whether OVERPRIMING using the throttle or the primer. Undertaken properly it is his view and mine that priming is best done using the accelerator pump which leads to better starts and is least likely to flood a cylinder. Most racing motor engineers i've spoken to hate the idea of neat fuel being sprayed into cylinders. Cylinder wash being the main concern. Also with a hot engine an exhaust fire is more likely even with light priming when using the primer.
When using the primer should the cylinder be flooded the fuel will run back into the hot air box just as it may using the throttle to prime.
There is no difference in that respect therefore whether OVERPRIMING using the throttle or the primer. Undertaken properly it is his view and mine that priming is best done using the accelerator pump which leads to better starts and is least likely to flood a cylinder. Most racing motor engineers i've spoken to hate the idea of neat fuel being sprayed into cylinders. Cylinder wash being the main concern. Also with a hot engine an exhaust fire is more likely even with light priming when using the primer.
Joined: Mar 2007
Posts: 420
Likes: 0
From: Right here
Just wait till you start flying aircraft with fuel-injected engines: It is some kind of a black art: many have tried, few have mastered. Sometimes it just seems that moving the throttle/mixture in some random order works best
One thing could be when priming by the book; fuel pump on, then move mixture towards full rich until you get an indication on the fuel "flow" (=pressure) gauge, then mixture cut-off and fuel pump off. The amount of priming you get that way will depend on how fast you move the mixture. Mixture full rich, fuel pump on, indication on fuel flow gauge, wait one second, fuel pump off, mixture cut off; seems to work better and more consistently. No priming when hot; the worst that can happen if you underprime is that it won't fire at all, so then you just stop what you're doing, prime, and crank again, it will fire.
Joined: Jan 2008
Aviation Qualifications: ATPL
Posts: 38
Likes: 63
From: The Smaller Antipode
Engine Starting
Now for something totally different ! How do you start a 1960 VW 1200 cc Beetle engine without impulse mags. as fitted to my Druine Turbulent ? and pls.don't say 'with difficulty' - I know that ! Squirting neat Avgas down the carb throat and pulling 8 blades sometimes works. I always achieve a start, but never really know what combination of choke and throttle worked that time. Thanks.
Joined: Sep 2003
Posts: 0
Likes: 0
From: UK,Twighlight Zone
Just wait till you start flying aircraft with fuel-injected engines: It is some kind of a black art: many have tried, few have mastered. Sometimes it just seems that moving the throttle/mixture in some random order works best
Joined: Jan 2006
Posts: 157
Likes: 0
From: Agion Oros
Engine Starts
This is all getting very protracted. best advice is what 'fireflybob' said, start the engine as directed by the aircrafts POH, which is part of the C of A, if that repeatedly fails refer the matter back to the engineer, it could indicate an underlying problem!
Joined: Sep 2002
Posts: 487
Likes: 0
From: Daventry UK
I agree that it's getting protracted, but at least part of that is because some POH's are remarkably silent on the issue. The PA-28-161 POH for instance says to prime if the engine won't start, but makes no reference as to how, or how much, to prime.
As I said earlier, I'm convinced that much of this problem stems from 'difficult' engines that engineers and / or owners fail to rectify. In practice in most cases the underlying machinery is capable of satisfactory starting without extremes of cranking and priming. It is the same owners who will end up paying for new starter motors or much worse and I suggest that it is short sighted not to deal with these issues when they arise.
As I said earlier, I'm convinced that much of this problem stems from 'difficult' engines that engineers and / or owners fail to rectify. In practice in most cases the underlying machinery is capable of satisfactory starting without extremes of cranking and priming. It is the same owners who will end up paying for new starter motors or much worse and I suggest that it is short sighted not to deal with these issues when they arise.
