Cowls closed or open on first engine start?
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Cowls closed or open on first engine start?
Whats better - leave the cowls open for the first engine start on a relatively cold morning or leave them closed to heat the engine oil up faster.
Any pluses or minuses with either approach??
Thanks ppl.
Mr G.
Any pluses or minuses with either approach??
Thanks ppl.
Mr G.
Grandpa Aerotart
If you remember to open them before it is an issue then probably no big deal...but I know I would forget sooner or later.
If you look at the first 10-12 inches of each blade you will see that they are round...no aerofoil shape at all...the only air going through the cowl at idle is what will be sucked in the front by the venturi effect of air going past the cowl flaps and sucking air out.
I tend to think it doesn't get cold enough in Oz to be bothered given the risks of eventually forgetting them and taking off with closed cowl flaps.
If you look at the first 10-12 inches of each blade you will see that they are round...no aerofoil shape at all...the only air going through the cowl at idle is what will be sucked in the front by the venturi effect of air going past the cowl flaps and sucking air out.
I tend to think it doesn't get cold enough in Oz to be bothered given the risks of eventually forgetting them and taking off with closed cowl flaps.
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Close them.
Start the engine, wait till the oil temp needle moves into the green and corresponding increase CHT needle.
Open cowl flaps to taxi and temps should be good by the time you line up.
Works well for C185`s and 188`s, particularly when you are paying the maintenance bills..
For shutdown 2 minutes at idle, flaps open. check mags- idle cutoff and close cowl flaps.
Deters the birds and snakes coming up from underneath into the cowl while parked in the open.
Start the engine, wait till the oil temp needle moves into the green and corresponding increase CHT needle.
Open cowl flaps to taxi and temps should be good by the time you line up.
Works well for C185`s and 188`s, particularly when you are paying the maintenance bills..
For shutdown 2 minutes at idle, flaps open. check mags- idle cutoff and close cowl flaps.
Deters the birds and snakes coming up from underneath into the cowl while parked in the open.
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I personally keep the cowls closed for start up and taxi and then I have made them in my checks to open them as I enter the runway.
Keeping the cowls closed will warm the engine up a little quicker (less cold air escaping out the cowls). I also keep them in the closed position when I shut down, again to keep the engine bay area warmer (in the event I have a fast turn around, plus it also saves on re-warming the engine for extended periods of time)
Hope this helps!
CMN
Keeping the cowls closed will warm the engine up a little quicker (less cold air escaping out the cowls). I also keep them in the closed position when I shut down, again to keep the engine bay area warmer (in the event I have a fast turn around, plus it also saves on re-warming the engine for extended periods of time)
Hope this helps!
CMN
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I have to agree with Chimbu's first instincts.
If I were you Chimbu I would stick with what you are doing. The advantages are minimal, the cost if u get it wrong ....................
Well I guess its a don't come in on Monday situation.
If I were you Chimbu I would stick with what you are doing. The advantages are minimal, the cost if u get it wrong ....................
Well I guess its a don't come in on Monday situation.
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Question to ponder....
Is there an opposite to shock cooling, i.e. heating the cylinders to quickly, like putting a cold glass into boiling water, could it cause cracked cylinders?
Yes a genuin question for the techies
Is there an opposite to shock cooling, i.e. heating the cylinders to quickly, like putting a cold glass into boiling water, could it cause cracked cylinders?
Yes a genuin question for the techies
Mr Garrison,
Well spank my arse and call me Charlie
.
By the way children, Mr Head says "just do it the exact way they write it in the POH or AFM, that way your butt is covered. Remember there is nothing funny about being exposed".........
Well spank my arse and call me Charlie
.By the way children, Mr Head says "just do it the exact way they write it in the POH or AFM, that way your butt is covered. Remember there is nothing funny about being exposed".........
Metrosexual
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I seem to remember something form a Piper manual (Aerostar or Chieftain??) recommending the cowls open for start. Had something to do with damage to the electrical wiring in the engine bay if you run the motor with the cowls closed at start.
Always had them open for start - never had a problem letting them idle up to op temp 'naturally'....
Always had them open for start - never had a problem letting them idle up to op temp 'naturally'....
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I can't imagine that cowl flap setting would cause much difference in how quickly the engine warms up unless the OAT was really cold (-10 or less) and there was a strong wind blowing.
Also, wouldn't having the cowl flaps open allow a more even temperature between cylinders (front compared to back)?
Cheers,
NK.
Also, wouldn't having the cowl flaps open allow a more even temperature between cylinders (front compared to back)?
Cheers,
NK.
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Read the aircraft manufacturer's POH. If it says cowl flaps open before engine start then simply accept that. Severe overheating of electrical leads and associated engine components can occur if you ignore the manufacturer's POH advice. Never blindly accept another pilot's advice on anything - stick to the POH and the lawyers won't eat you up if something should go wrong.
I don't know what type your talking about but for the old piper
Start engine, close the cowls
Do runups etc, shut down at terminal. Leave checklist at cowl flaps open.
It'll keep em warm, and yes Oz does get cold. Plenty of Valley towns on the east coast get as low as -10 on a winters morning. obviousy in summer why bother.
Sometimes there is no drama taking off with em closed, because you are supposed to monitior temps on your departure anyhow. so you'd notice a strange reading before you got any probs. Having said that, i wouldn't do it on purpose. The C310 on a summers day would be an obvious mistake.
Speeds high, yes. Shock cooling is the more common case, but the problem is really with rates of change. from memory the ol PA31 would always be around 350~400F by 500 feet no matter what temp you started at. going from 100F to 400 in less than a minute is just as bad as the opposite.
Anyways its snowing out, and i think that is my longest post ever.
Powder to the people.
Start engine, close the cowls
Do runups etc, shut down at terminal. Leave checklist at cowl flaps open.
It'll keep em warm, and yes Oz does get cold. Plenty of Valley towns on the east coast get as low as -10 on a winters morning. obviousy in summer why bother.
Sometimes there is no drama taking off with em closed, because you are supposed to monitior temps on your departure anyhow. so you'd notice a strange reading before you got any probs. Having said that, i wouldn't do it on purpose. The C310 on a summers day would be an obvious mistake.
Speeds high, yes. Shock cooling is the more common case, but the problem is really with rates of change. from memory the ol PA31 would always be around 350~400F by 500 feet no matter what temp you started at. going from 100F to 400 in less than a minute is just as bad as the opposite.
Anyways its snowing out, and i think that is my longest post ever.
Powder to the people.
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Agree with everyone on the POH. Why do something contrary to the POH just because it sounds good. The guys who designed and manufactured these aircraft have a reason why they they include certain procedures in their checklists. As for engine oil, aircraft engines and oil heat up very quickly anyway due to a high viscosity index (similar viscosity over a range of temperatures).
The engine is designed to operate over a very wide range of temperatures so if you use the manufacturers recommendations you can't go wrong. Aircraft engines are designed to be run hard. They are robust so I don't know why people baby them!
The engine is designed to operate over a very wide range of temperatures so if you use the manufacturers recommendations you can't go wrong. Aircraft engines are designed to be run hard. They are robust so I don't know why people baby them!
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A company I worked for a few years ago operating Aero Commanders the company procedure was to have the cowl flaps closed all the time. If you needed to open them for overheating there was something wrong with the engine. I operated them from Melbourne to FNQ and no problems with temps!!
The company owns approx 40 aero commanders now with no problems having cowl flaps closed. The boss is an aircraft engineer who Rockwell go to have questions answered on the aircraft they built and designed.
Anyway just one type of aircraft/engine (lycoming IO540) from memory.
Non turbo so that can make a difference to whether they are needed.
The company owns approx 40 aero commanders now with no problems having cowl flaps closed. The boss is an aircraft engineer who Rockwell go to have questions answered on the aircraft they built and designed.
Anyway just one type of aircraft/engine (lycoming IO540) from memory.
Non turbo so that can make a difference to whether they are needed.
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The POH or AFM must be the guide to what to do.
Remembering there are different design features in many aircraft. The C310 is a classic, still called cowl flaps, but they are used in a very differet way, to that which most would call normal.
My point is that different manafacturers use different methods of skinning the same cat. One method will nor nessecarily work for all aircraft types.
1. Know your aircraft POH/AFM,
2. Know your systems,
3. Know your Operations Manual/Procedures.
4. If you fly more than one type (especialy by manafacturer), then things may be different.
5. Be wary of Instructors/Owners telling you how to do things unless it is in the book/'s.
Richo
Remembering there are different design features in many aircraft. The C310 is a classic, still called cowl flaps, but they are used in a very differet way, to that which most would call normal.
My point is that different manafacturers use different methods of skinning the same cat. One method will nor nessecarily work for all aircraft types.
1. Know your aircraft POH/AFM,
2. Know your systems,
3. Know your Operations Manual/Procedures.
4. If you fly more than one type (especialy by manafacturer), then things may be different.
5. Be wary of Instructors/Owners telling you how to do things unless it is in the book/'s.
Richo
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Originally Posted by Richo
The C310 is a classic, still called cowl flaps, but they are used in a very differet way, to that which most would call normal
R
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I recall from a few years back that the C310 POH required the cowl flaps to be open on descent to keep the engine warm, therefore open most if not all of the time. I still don't know why. It must have been something to do with the design of the engine naucelle where the cowl flaps are inside the naucelle and are situated on top of the engine, as opposed to the conventional, under the engine design.
Originally Posted by Rat****
I musta been asleep during endorsment training on the C310. Tell me more about the "very different way" ??
R
R
If you "open the cowl flaps" prior to take off on a hot day (well, any day almost) just watch those CHT needles rise...
Must be a North American winter thing.
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GA Joe.
You said:
So God Almighty does live at Essendon on the northern tarmac after all. What juvenile rubbish you write on these esteemed pages.
You said:
The boss is an aircraft engineer who Rockwell go to have questions answered on the aircraft they built and designed.