Priming inflight
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Priming inflight
What are the possible consequences of priming a piston engine in flight when the engine is running?
Re: Priming inflight
It runs rich momentarily & you waste fuel.
"Carelessness and overconfidence are more dangerous than deliberately accepted risk." -Wilbur Wright
- Cat Driver
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Re: Priming inflight
Why would you even think of priming in flight?
The hardest thing about flying is knowing when to say no
After over a half a century of flying no one ever died because of my decision not to fly.
After over a half a century of flying no one ever died because of my decision not to fly.
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Re: Priming inflight
If the engine has failed and you have checked all the obvious things, and have time for more troubleshooting, it is worth trying a shot of prime to see if the engine will run. I have heard of a case where the pilot was able to use the primer to get enough engine power extend the glide enough to make it to a nearby airport.
One issue that does not seem to be well known in flight schools is that an unlocked primer could bypass enough extra fuel to to give the engine such an over rich mixture that it will run rough. If the engine is running rough and you have checked for carb ice and the mixture control, it would be worth giving the primer knob a pull to see if it was locked in.
One issue that does not seem to be well known in flight schools is that an unlocked primer could bypass enough extra fuel to to give the engine such an over rich mixture that it will run rough. If the engine is running rough and you have checked for carb ice and the mixture control, it would be worth giving the primer knob a pull to see if it was locked in.
Re: Priming inflight
'Been there, done that... I was able to stretch the glide and warm the engine enough and use carb heat, that at a lower altitude I could continue with great caution (it was a night flight, so I was well motivated to remain airborne). Carb air temperature indicator installed shortly after! It is necessary to find a partial throttle setting appropriate to pumping the primer steadily.I have heard of a case where the pilot was able to use the primer to get enough engine power extend the glide ...
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Re: Priming inflight
One might want to go to altitude, ( over an airport or lake ) pull the mixture and feed in primer to keep the engine going at cruise, you will loose some power as you reach the bottom of the stroke ,,,,,
Re: Priming inflight
Because every checklist involves checking the primer being locked. Hence, the question, what would happen if the primer were unlocked or an accidental shot of primer was sprayed!Cat Driver wrote:Why would you even think of priming in flight?
Re: Priming inflight
You suspected carb ice? and priming helped warm the engine?PilotDAR wrote:'Been there, done that... I was able to stretch the glide and warm the engine enough and use carb heat, that at a lower altitude I could continue with great caution (it was a night flight, so I was well motivated to remain airborne). Carb air temperature indicator installed shortly after! It is necessary to find a partial throttle setting appropriate to pumping the primer steadily.I have heard of a case where the pilot was able to use the primer to get enough engine power extend the glide ...
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Re: Priming inflight
And how does one accidentally give the engine a shot of prime in flight?what would happen if the primer were unlocked or an accidental shot of primer was sprayed!
The hardest thing about flying is knowing when to say no
After over a half a century of flying no one ever died because of my decision not to fly.
After over a half a century of flying no one ever died because of my decision not to fly.
Re: Priming inflight
Primer wasn't locked, moves slowly out due to vibrations, you notice it and push it back in to where it belongs in a reflex.Cat Driver wrote:And how does one accidentally give the engine a shot of prime in flight?what would happen if the primer were unlocked or an accidental shot of primer was sprayed!
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
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Re: Priming inflight
I should not have asked.Primer wasn't locked, moves slowly out due to vibrations, you notice it and push it back in to where it belongs in a reflex.
So what you are saying is the pilot did not check the primer was locked before take off and while flying noticed it was unlocked and had vibrated out so instead of slowly pushing it back in and locking it the pilot jammed it back in and temporarily increased the mixture to over rich?
Yeh, that sounds believable and reflects on poor airmanship and poor training more than anything else.
The hardest thing about flying is knowing when to say no
After over a half a century of flying no one ever died because of my decision not to fly.
After over a half a century of flying no one ever died because of my decision not to fly.
Re: Priming inflight
He was asking hypothetically.
I know what happens. Nothing, really. Engine will run rough for a few seconds, then continue on. Was that so hard?
I know what happens. Nothing, really. Engine will run rough for a few seconds, then continue on. Was that so hard?
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Re: Priming inflight
No it was not so hard.I know what happens. Nothing, really. Engine will run rough for a few seconds, then continue on. Was that so hard?
There are many types of engine priming.
Some are more effective than others.
Which method of priming do you think is most effective and will induce more fuel into the engine, throat priming or cylinder priming?
The hardest thing about flying is knowing when to say no
After over a half a century of flying no one ever died because of my decision not to fly.
After over a half a century of flying no one ever died because of my decision not to fly.
Re: Priming inflight
You forgot the third kind, manifold priming.
Each has its advantages and disadvantages. Cylinder priming gets the fuel right into the intake port, but usually not all cylinders have primers. Throat primers will supply all cylinders, but you have to get the charge into the cylinders with cranking otherwise the fuel can condense and drain into the air box. Manifold priming is in between, closer to the cylinders than a throat primer, but able to supply more than one cylinder.
With the engine running, things are moving so fast it doesn't matter where the primer is. Either you really rich out a few cylinders or partially rich out all of them.
Each has its advantages and disadvantages. Cylinder priming gets the fuel right into the intake port, but usually not all cylinders have primers. Throat primers will supply all cylinders, but you have to get the charge into the cylinders with cranking otherwise the fuel can condense and drain into the air box. Manifold priming is in between, closer to the cylinders than a throat primer, but able to supply more than one cylinder.
With the engine running, things are moving so fast it doesn't matter where the primer is. Either you really rich out a few cylinders or partially rich out all of them.
Re: Priming inflight
I noticed my Lycoming only has primers on 3 cylinders. What is the purpose of 3 instead of 4?
"Carelessness and overconfidence are more dangerous than deliberately accepted risk." -Wilbur Wright
Re: Priming inflight
Is there anything plugged into the 4th cylinder? Manifold pressure gauge?
Re: Priming inflight
Just a solid plug.
"Carelessness and overconfidence are more dangerous than deliberately accepted risk." -Wilbur Wright
Re: Priming inflight
The purpose then would be it's cheaper (or for a homebuilt, less work). I flew one last month that only had two cylinders primed.
Re: Priming inflight
So what you are saying is that no (student) pilot ever made the mistake of not properly locking the primer? I've seen it happen, so yes, it is believable. Even if you push it back in slowly, you are still priming the engine in flight. It's something you are not supposed to do, which makes the question of "what would happen if..." very interesting.Cat Driver wrote: So what you are saying is the pilot did not check the primer was locked before take off and while flying noticed it was unlocked and had vibrated out so instead of slowly pushing it back in and locking it the pilot jammed it back in and temporarily increased the mixture to over rich?
Yeh, that sounds believable and reflects on poor airmanship and poor training more than anything else.
As an AvCanada discussion grows longer:
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
-the probability of 'entitlement' being mentioned, approaches 1
-one will be accused of using bad airmanship
- Cat Driver
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- Posts: 18921
- Joined: Sun Feb 15, 2004 8:31 pm
Re: Priming inflight
Without sounding pedantic on this issue I was merely stating that the use of the primer if one is in the airplane is something that the student should understand and use properly during basic training, reflex actions are not a sign of proper training, thinking before acting is.So what you are saying is that no (student) pilot ever made the mistake of not properly locking the primer? I've seen it happen, so yes, it is believable.
The correct use of engine controls was one of the most frustrating problems I had with instructors when I owned a flight school.
It was common for them to set a power setting and then control taxi speed with the brakes, then on take off they just slammed the throttle full in like it was some kind of contest to see how fast they could get it from taxi RPM to full power.
When I read the above it said " you " not the student.Primer wasn't locked, moves slowly out due to vibrations, you notice it and push it back in to where it belongs in a reflex.
The hardest thing about flying is knowing when to say no
After over a half a century of flying no one ever died because of my decision not to fly.
After over a half a century of flying no one ever died because of my decision not to fly.