Cowls closed or open on first engine start?
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People, people, I don't believe what I read here
CAR 138 Pilot to comply with requirements, etc of aircraft’s flight
manual, etc
(1) If a flight manual has been issued for an Australian aircraft, the pilot
in command of the aircraft must comply with a requirement,
instruction, procedure or limitation concerning the operation of the
aircraft that is set out in the manual.
Penalty: 50 penalty units.
(2) If a flight manual has not been issued for an Australian aircraft and,
under the relevant airworthiness standards for the aircraft, the
information and instructions that would otherwise be contained in an
aircraft’s flight manual are to be displayed either wholly on a placard,
or partly on a placard and partly in another document, the pilot in
command of the aircraft must comply with a requirement, instruction,
procedure or limitation concerning the operation of the aircraft that is
set out:
(a) on the placard; or
(b) on the placard or in the other document.
Penalty: 50 penalty units.
All the pistons I've had the privelige to sit behind included operating instructions for preheating and oil dilution if starting below a given temp. And ALL included starting/warm up with cowl flaps open. CHT only reads just that, not whats happening in the rest of the engine. What I read here is a testament to the abuse engines will withstand and still operate. 1930's design and understressed is saving a lot of ass'es out there I think.
CAR 138 Pilot to comply with requirements, etc of aircraft’s flight
manual, etc
(1) If a flight manual has been issued for an Australian aircraft, the pilot
in command of the aircraft must comply with a requirement,
instruction, procedure or limitation concerning the operation of the
aircraft that is set out in the manual.
Penalty: 50 penalty units.
(2) If a flight manual has not been issued for an Australian aircraft and,
under the relevant airworthiness standards for the aircraft, the
information and instructions that would otherwise be contained in an
aircraft’s flight manual are to be displayed either wholly on a placard,
or partly on a placard and partly in another document, the pilot in
command of the aircraft must comply with a requirement, instruction,
procedure or limitation concerning the operation of the aircraft that is
set out:
(a) on the placard; or
(b) on the placard or in the other document.
Penalty: 50 penalty units.
All the pistons I've had the privelige to sit behind included operating instructions for preheating and oil dilution if starting below a given temp. And ALL included starting/warm up with cowl flaps open. CHT only reads just that, not whats happening in the rest of the engine. What I read here is a testament to the abuse engines will withstand and still operate. 1930's design and understressed is saving a lot of ass'es out there I think.
Grandpa Aerotart
Have pondered and think i will keep doing what I have been doing for 25 years
BA...not everything in a POH is gospel just because CASA threatens 50 strokes of the cane for not doing it.
As an example mine says don't fly LOP and that is a crock written by the ill informed overseen by the company Lawyer.
So if you factor the takeoff distance from the performance data in the POH do you risk 50 points...or if you don't and crash?
BA...not everything in a POH is gospel just because CASA threatens 50 strokes of the cane for not doing it.
As an example mine says don't fly LOP and that is a crock written by the ill informed overseen by the company Lawyer.
(1) If a flight manual has been issued for an Australian aircraft, the pilot
in command of the aircraft must comply with a requirement,
instruction, procedure or limitation concerning the operation of the
aircraft that is set out in the manual.
Penalty: 50 penalty units.
in command of the aircraft must comply with a requirement,
instruction, procedure or limitation concerning the operation of the
aircraft that is set out in the manual.
Penalty: 50 penalty units.
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Chimbu,
With you all the way. Our ops manual (it is approved by CASA isn't it?)included take off data which didn't comply with the regs or flight manual. But when it comes to engineering matters I'm inclined to go with the engineers. When the US Navy told me how to operate thier big radials I figured they knew what they were talking about. Was my faith misplaced? BTW agree fully with the LOP and sure you are familiar with John Deakins treatise. I recall flying with one guy in a 182 who flew with full flaps open and closed for taxi. Don't think thats what Cessna had in mind.
With you all the way. Our ops manual (it is approved by CASA isn't it?)included take off data which didn't comply with the regs or flight manual. But when it comes to engineering matters I'm inclined to go with the engineers. When the US Navy told me how to operate thier big radials I figured they knew what they were talking about. Was my faith misplaced? BTW agree fully with the LOP and sure you are familiar with John Deakins treatise. I recall flying with one guy in a 182 who flew with full flaps open and closed for taxi. Don't think thats what Cessna had in mind.
Grandpa Aerotart
Brian I once poured my heart and soul into writing an Ops Manual for a corporate jet operation. I reckon I spent easily 40 hrs a week for 6-8 mths just doing that, on top of everything else.
When it was finshed our ATO read it and suggested it was one of the best he'd seen..."Gee thanks..how long before CASA reads, digests and approves it?"
"Oh CASA will never read it!"
CASA is a rubber stamp operation with a big stick...and precious little understanding, much of the time, about what they are actually rubber stamping.
To add insult to injury, after it was approved, a less than competent, and completly dishonest non flying 'manager' refused to issue it to the pilots and CASA did precisely nothing about it....it just never got printed while I was there.
I wouldn't pi$$ on CASA if it was on fire.
Sorry...CASA is one of my sore points...best not think about them...Hooosaaahhh
When it was finshed our ATO read it and suggested it was one of the best he'd seen..."Gee thanks..how long before CASA reads, digests and approves it?"
"Oh CASA will never read it!"
CASA is a rubber stamp operation with a big stick...and precious little understanding, much of the time, about what they are actually rubber stamping.
To add insult to injury, after it was approved, a less than competent, and completly dishonest non flying 'manager' refused to issue it to the pilots and CASA did precisely nothing about it....it just never got printed while I was there.
I wouldn't pi$$ on CASA if it was on fire.
Sorry...CASA is one of my sore points...best not think about them...Hooosaaahhh
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Open's the go for all ground ops.
You will strugle in vain to find any science based article on the subject that suggests otherwise. And no the POH is often not a science based document, but a start point till you grow wisdom. The issue of CHT's s only part of the story, engine accessories, magneto's, hoses, turbo's etc last longer if temperature's are kept lower.
There are some good article's out there that take information from aircraft setup to measure temps from many points on the engine during the various stages of ground and flight. This research points to things like poor air flow through the engine bay during ground ops, due lack of pressure differencial between top and bottom deck. The result being uneven cooling which can lead to cylinder disstortion and induce significant levels of hoop stress in cylinders in some instalations.
Of course having said all this there may some circumstance where it may be prudent to clöse or partially clöse them, I imagine some installations may have difficulty getting the oil temps up in artic conditions.
A number of aircraft can probably tolerate closed cowls on the ground, a la the Shrike without inducing visible damage, so you end with people extolling the virtue of closed cowls for all sorts of wierdo reasons, if these people appear older and wiser, you will probably adopt the advice as gospel and there by another myth or old wives tale is put or kept in circulation.
Shock cooling/heating is another area that has grown to mythical proportions over the years. Yes there is basis to it but many would not be aware.
Some areas of internet research for cowl flaps are the Sacremento Sky Ranch, CAFE Foundation, and AVwebs engine articles, if any one is interested, these are a good starting point.
Regards
M
You will strugle in vain to find any science based article on the subject that suggests otherwise. And no the POH is often not a science based document, but a start point till you grow wisdom. The issue of CHT's s only part of the story, engine accessories, magneto's, hoses, turbo's etc last longer if temperature's are kept lower.
There are some good article's out there that take information from aircraft setup to measure temps from many points on the engine during the various stages of ground and flight. This research points to things like poor air flow through the engine bay during ground ops, due lack of pressure differencial between top and bottom deck. The result being uneven cooling which can lead to cylinder disstortion and induce significant levels of hoop stress in cylinders in some instalations.
Of course having said all this there may some circumstance where it may be prudent to clöse or partially clöse them, I imagine some installations may have difficulty getting the oil temps up in artic conditions.
A number of aircraft can probably tolerate closed cowls on the ground, a la the Shrike without inducing visible damage, so you end with people extolling the virtue of closed cowls for all sorts of wierdo reasons, if these people appear older and wiser, you will probably adopt the advice as gospel and there by another myth or old wives tale is put or kept in circulation.
Shock cooling/heating is another area that has grown to mythical proportions over the years. Yes there is basis to it but many would not be aware.
Some areas of internet research for cowl flaps are the Sacremento Sky Ranch, CAFE Foundation, and AVwebs engine articles, if any one is interested, these are a good starting point.
Regards
M
.
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Going through the manuals I have the military ones provide guidance. One says open for all ground ops (including arctic conditions and includes a cautionary note about not closing to hasten warm up due to possible breakdown of portion of the ignition harness) where as another type has if OAT is below minus 23C to close flaps until oil reaches 70C or cylinder head 150C. I guess it may reflect the lack of testing done on GA types if the POH does not offer guidance. Many bemoan the quality of GA manuals after all.
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I recall an owner that had the cowl flaps fixed open on a Cessna 210 in order to reduce servicing costs on the linkages. You have to be really hurt for money if you cannot afford work on cowl flap linkages during the 100 hourly. CASA even approved the AD that let him do it. What the CASA airworthiness people failed to realise was that the POH called for the cowl flaps to be immediately closed if a engine fire occurred. Pretty hard to do that in flight when they are fixed open.
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Originally Posted by A37575
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:
So God Almighty does live at Essendon on the northern tarmac after all. What juvenile rubbish you write on these esteemed pages.
After reading your posts I have come to the conclusion it is okay for you to express an opinion as that is what this forum is about however I am not allowed to do that. All I was doing was express an opinion on how on aircraft operator/engineer operated his aircraft which for someone who shells out alot of money to maintain he must have some idea. Again not trying to say this is my knowledge on the subject. As questions where raised on the operation of cowl flaps and I was just extending the experience of one operator. So A37575 you post about your experiences of a 210 operator doing his thing. Who says he is wrong or right its his aircraft!!! Get off your high horse and just read other peoples posts as aircraft are not operated the same everywhere in GA. Even in the airlines aircraft are operated to SOP's which differ from airline to airline and even (oh heavens here it comes!!)
the aircraft manufacturer. Even though airlines are more and more aligning their SOP's to the manufacturer. As you should know! however we are not talking about the airlines. Its about GA? So before you go criticising anyone else even GOD!! from Essendon!! Why don't you just listen to what people have to say. Even though I know its hard for you. Can't teach an old dog new tricks!
Last edited by GAJoe; 12th Aug 2006 at 18:01.
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Originally Posted by A37575
I recall an owner that had the cowl flaps fixed open on a Cessna 210 in order to reduce servicing costs on the linkages. You have to be really hurt for money if you cannot afford work on cowl flap linkages during the 100 hourly. CASA even approved the AD that let him do it. What the CASA airworthiness people failed to realise was that the POH called for the cowl flaps to be immediately closed if a engine fire occurred. Pretty hard to do that in flight when they are fixed open.
IF the Pilot Operating handbook says Cowl flaps open for start, Open them, Especially if she is a tricky one to start for added cooling of the starter and associated solonoid. Once A/C has been started close them if cold or if the temps are green, it was a hot start, and, you need the extra cooling, open them for taxi. Taxi runup with cowl flaps as required ensuring your temps stay in the green. Lining up open them and close when airborne as required. It is bad to run the head temps too cold and at between 30K and 50K for a overhaul on your engine coming from the operators cheque book, you may want to fly as whats best for the engine.
Dont open the cowls on finals, else you will shock cool the motor and who wants a cracked head or worse. Open in the go around as required, i generally won't open the cowl flaps in climb unless its a long climb or the temps are rising. Remember you dont need to open the cowl flaps full either. Partial opening may be all that is required to keep the temp in the green. When i've been low on a hot day i have used partial cowl flaps for extra cooling to keep the temps managable and sensible.
I basically monitor the temp guage and use the tools at my disposal to keep the temps in an acceptable range. Good engine handling is paramount especially if you progress into equipment with forced induction such as turbo or superchargers.
I would also refrain from leaving a parked A/C with the cowl flaps open.
AIRMANSHIP comes into this, you can fly the plane, OR fly the plane well.
Shock cooling eh? I for one don't really believe in such a thing and my belief was further cemented when I read an article on AvWeb on the very topic...
Thoughts?
Thoughts?
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Experiment then, you have your MP at around 12" on base in most Small piston CSU type setups. On final, open your cowl flaps and watch the two temp guages (paying attention to the runway of course
oil temp wont fluctuate much, but your cyl head temp will rapidly drop! (hopefully you own the plane and not your employer, cause i may fly this plane one day)
Tell me this is good, especially if you can consider metal fatigue, and of course the differant rates at which the head will cool to the block it is bolted too due to differant metals/grades/composition etc!
oil temp wont fluctuate much, but your cyl head temp will rapidly drop! (hopefully you own the plane and not your employer, cause i may fly this plane one day)Tell me this is good, especially if you can consider metal fatigue, and of course the differant rates at which the head will cool to the block it is bolted too due to differant metals/grades/composition etc!
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Hi 4 spooled,
Cooling is often most rapid after shut down, are you advocating not shuting down the engine?
You mentioned you moniter the cht on long climbs, and only open cowls as temps climb, how many cht probes you got, if it's just the one how the hell do you really know what the others are up to?
You mentioned it is bad to run cht's to low but you didn't state a value, love to know what is to cold, I have read one tech article on this subject, what research article/s are you referencing here.
Shock cooling has a bit to do amongst other things with the tensile strength of the alloys in the head. If your engine temp is already low ie. approach phase, the tensile strengths are quite high and you are most unlikely to induce shock cooling resulting in cracking. Again at some point you are going to have to turn the mother off. Or even heaven forbid fly through heavy rain.
Love to here back on the temp low research articles.
Regards
M
Cooling is often most rapid after shut down, are you advocating not shuting down the engine?
You mentioned you moniter the cht on long climbs, and only open cowls as temps climb, how many cht probes you got, if it's just the one how the hell do you really know what the others are up to?
You mentioned it is bad to run cht's to low but you didn't state a value, love to know what is to cold, I have read one tech article on this subject, what research article/s are you referencing here.
Shock cooling has a bit to do amongst other things with the tensile strength of the alloys in the head. If your engine temp is already low ie. approach phase, the tensile strengths are quite high and you are most unlikely to induce shock cooling resulting in cracking. Again at some point you are going to have to turn the mother off. Or even heaven forbid fly through heavy rain.
Love to here back on the temp low research articles.
Regards
M
then I'm always half right.....or half wrong
So maybe CASA's penalty is only 25 lashes instead of 50 lashes?
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Too hot is outside and above the green range, as is, too cold below. If you open the cowl flaps on final, you have gone from normal operating temps in the green range, to below this rather quickly.
The subsequent idling from the runway to the parking area followed by shutdown checks all at 1000 - 1200 rpm etc is usually enough time for the engine to cool down to be safely shut down.
Some operators even require that the CSU is not to be "fine" on finals but rather left in circuit power settings along with closed cowl flaps, so max thrust is not available on go a around or if you forgot to put the pitch fine before applying go around power, you get a bit of run away pitch on your hands, which never makes the pax feel terribly at ease!!
Sunfish, like your style hahahaha
The subsequent idling from the runway to the parking area followed by shutdown checks all at 1000 - 1200 rpm etc is usually enough time for the engine to cool down to be safely shut down.
Some operators even require that the CSU is not to be "fine" on finals but rather left in circuit power settings along with closed cowl flaps, so max thrust is not available on go a around or if you forgot to put the pitch fine before applying go around power, you get a bit of run away pitch on your hands, which never makes the pax feel terribly at ease!!
Sunfish, like your style hahahaha
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GA Joe. Sorry if I hurt your feelings. No offence meant. Aviation is full of perceived "Legends" and no shortage of personal opinions on how to skin a cat or operate an engine and how to fly an aeroplane. "He is a legend in his own mind" is an apt description of some I know and strange thing is that someone can crash an aircraft out of his own stupidity but his praises will be sung from on high by former or current students.
To refer to a certain LAME as so grand that even the aircraft manufacturer's bow to his knowledge is surely just a teensy-weensy bit exaggerated, don't you think? As you rightly say, GA aircraft are often operated differently to the designers recommendations by different operators. Believe me when it comes to the crunch, in court the lawyers for the dead, maimed, or merely badly frightened will opt for the designers (manufacturer's if you like that word) technical expertise rather than a mere pilot's personal opinion. The POH advice is hard to refute in court. You can rubbish my references to manufacturer's recommendations as much as you like - but believe me, you would be done like a dinner if you went against those recommendations and cost someone some money through negligence and bad judgement.
To refer to a certain LAME as so grand that even the aircraft manufacturer's bow to his knowledge is surely just a teensy-weensy bit exaggerated, don't you think? As you rightly say, GA aircraft are often operated differently to the designers recommendations by different operators. Believe me when it comes to the crunch, in court the lawyers for the dead, maimed, or merely badly frightened will opt for the designers (manufacturer's if you like that word) technical expertise rather than a mere pilot's personal opinion. The POH advice is hard to refute in court. You can rubbish my references to manufacturer's recommendations as much as you like - but believe me, you would be done like a dinner if you went against those recommendations and cost someone some money through negligence and bad judgement.
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A35755 I can concur with GA Joe, Rockwell do I belive seek GAMs advice and operational knowledge on Shrikes, after all why wouldnt they there probably the largest operator of this type.
4 Spooled not sure I would agree to much with this green arc stuff, you really need to know some real numbers here. I'll bet my bottom dollar the top of the green is far to hot and enters into the regime of seriously diminished tensile strength for cylinder head alloys.
If you can lay your hands on a tensile strength v temp graph printed by lycoming back in 1966 it clearly shows a steep decline after about 200c. You'll also find these same numbers reflected in Pratt and Whitney manuals. Off the top of my head it's something like 232c for crz and 5 min at 265c. No shades of colours stuff here but real numbers, it even sounds bloody convincing 232 not just rounded off to 230, this comes from proper tensile yield value tests. All this shades of colours on temp gauges, I'm sure stems from the design desire to make it all appear simple stuff for begining pilots.
Been a little while since I flown a type with a green arc for a cht but I seem to recall the low end is quite low and can't ever recall temps dropping out of it on approach. Sounds suss to me but you reckon you've seen it, I'll have to take your word for it.
Regards
M
4 Spooled not sure I would agree to much with this green arc stuff, you really need to know some real numbers here. I'll bet my bottom dollar the top of the green is far to hot and enters into the regime of seriously diminished tensile strength for cylinder head alloys.
If you can lay your hands on a tensile strength v temp graph printed by lycoming back in 1966 it clearly shows a steep decline after about 200c. You'll also find these same numbers reflected in Pratt and Whitney manuals. Off the top of my head it's something like 232c for crz and 5 min at 265c. No shades of colours stuff here but real numbers, it even sounds bloody convincing 232 not just rounded off to 230, this comes from proper tensile yield value tests. All this shades of colours on temp gauges, I'm sure stems from the design desire to make it all appear simple stuff for begining pilots.
Been a little while since I flown a type with a green arc for a cht but I seem to recall the low end is quite low and can't ever recall temps dropping out of it on approach. Sounds suss to me but you reckon you've seen it, I'll have to take your word for it.
Regards
M
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Why over complicate things in thie air "the bottom of this line is about this temp, the top is this etc"
In the POH it states anything is acceptable in the green arc..... keep the temp there!! simple!
In the POH it states anything is acceptable in the green arc..... keep the temp there!! simple!
Dont open the cowls on finals, else you will shock cool the motor and who wants a cracked head or worse.
Shock cooling I think, is a bit a of a furphy. I don't no how many times I've seen pilots constantly fiddling with the power settings on descent to avoid shock cooloing the engine. No more the 1" MP change per minute and it has to be at such and such a power setting 5 miles out, so on and so on.
Yet those same pilots in a Chieftan for example at top of climb, will pull the MP back to 31" from 38". A whole 7" all in one go!
In fact the power reduction at top of climb is where you will find the greatest change in CHT's, other than at start up. Not on descent.
232c for crz and 5 min at 265c
In the POH it states anything is acceptable in the green arc..... keep the temp there!! simple!