Loud "bang" during hot start

Twice recently I've heard a single loud "bang" during a hot (or really warm) start. Both times I realize I didn't prime as much as I usually do. What could this be (backfire, something else)? Do I need to check for damage anywhere?

I have an IO-540 w/ an impulse coupled mag and a Lightspeed plasma. I start on both (as I always have).

Thanks...

-Rob

Mine has too

Rob,

My hot start procedure if shut down in less than one hour is the following: no priming, open throttle 1/2-full open, start(have to crank longer than cold starts), mixture full rich, throttle to idle. I have slick start on LH mag and RH mag is grounded during start. It backfires about half the time during my hot starts. If one has a better procedure, I would like to know too.

On my IO-550 Bonaire Ag-Truck;

Hot Starts: Mags on both, mixture rich, throttle full forward, run the boost and high/emergency until flow needle registers, once needle moves: leave boost on, turn off the high/emergency, throttle back to idle/cracked, and start. No pop, bang, or kaboom for me.

Well for a start it is not a back fire. It is most likely an "after fire" in your exhaust.

A hot start will most likely result in for a second or so a few very lean charges going through that are not fired, and as others do the exhaust gases ignite the unburnt ones in the exhaust.

Hot start, Mixture ICO, throttle cracked about where 1700 RPM would be, I do not think the half way mark is necessary. And when it fires may well be too far, so as you crank and it first coughs into life, roll the mixture full rich, then lean back half way, turn on the boost pump to stop heat soaked pumps from vapour locking, and lean right back to peak rpm at a taxi speed.

Release brakes and taxi away.

Never failed in 600 hours

RV10inOz said:

Well for a start it is not a back fire. It is most likely an "after fire" in your exhaust.

A hot start will most likely result in for a second or so a few very lean charges going through that are not fired, and as others do the exhaust gases ignite the unburnt ones in the exhaust.

Hot start, Mixture ICO, throttle cracked about where 1700 RPM would be, I do not think the half way mark is necessary. And when it fires may well be too far, so as you crank and it first coughs into life, roll the mixture full rich, then lean back half way, turn on the boost pump to stop heat soaked pumps from vapour locking, and lean right back to peak rpm at a taxi speed.

Release brakes and taxi away.

Never failed in 600 hours

Click to expand...

My hot start technique is pretty much identical and works consistently.

Gooday DM,

You would hope so, its not like they are all radically different fuel systems

I have seen so many discussions on hot starts of various sorts, but once you understand what is going on in the fuel system, it becomes easy. Often the strange variations fluke success most of the time but fail once in a while, yet people persist with them not thinking about why.

Cheers
DB

Thanks, guys... my starting technique is similar, so I suspect the difference is indeed that I didn't prime enough in these two instances. Any possibility of exhaust damage?

-Rob

Rob,

NO NO NO,

WHERE DID I MENTION, OR DAVID MAIB MENTION "PRIMING"

That is for a cold start

Read my post again!!!

You priming when hot may well be the problem!!

COLD START
Prime for 3 seconds with WOT and full rich, watch fuel pressure rise to 20+PSI and count to three, close throttle and crack to a point that would give 1200 RPM and mixture idle cut off. Crank till she fires, then ramp up mixture, once stable lean to peak rpm an just past.

HOT start..... Read my post again. Do exactly what I say.....do NOTHING else.

It is that simple.

If n out go see David Maib.

I will try it with 1/2" or so open throttle next time. I am assuming no priming is necessary due to fuel that has ran out through injectors that I hear a few minutes after shut down. Thanks Rob for asking and for the answers guys.

On cold starts, I turn boost pump on with throttle 1/4" open, mixture idle cutoff, watch for good fpres, mixture rich for 4-6 sec depending on engine temp, idle cutoff, then start. No problem on cold starts. I am sure going to get some hot start practice soon with 90F temps around the corner.

Hot starts on an injected engine should not require priming. The fuel in the spider lines will boil on shutdown as the lines heatsoak and the fuel will squirt into the manifolds, so you are essentially starting a flooded engine.

On my IO360, hot starts are Mixture cutoff, throttle open, crank. On the first engine cough, continue crank and quickly shove mixture full rich first, then throttle back, I usually catch it right as it rises through 700 rpm. Works like a charm for me, but every engine has it's quirks.

I've always primed for a few seconds before a hot start. Maybe a coincidence, but I tried not priming once, and that was the first time I heard this loud noise during startup.

Is the theory behind afterfire and not priming for a hot start that the extra fuel will end up going through an open exhaust valve into the exhaust? If so, why isn't that a concern for cold starts, too?

Appreciate the info...

-Rob

On my hot starts I flush the lines for a second or so with the boost pump. If I don't the engine will start to quit right after it is running and I have to catch it with the boost pump to keep it running. It is warm starts that I hate after the plane is sitting for a couple of hours. I know not to bother trying to start it like a cold start then either. It never works.

Think cold carby car engines, choke required but not hot

The HOT PRIME is done on TCM engines but with mixture at ICO because you are not priming the engine with fuel, just the fuel pump.

So again I say to others reading this follow my instructions and lead a happy life. Those other variations might work for some most of the time, but when your battery gives up in a far away place one Sunday afternoon .......you know the rest

Like Troy I have had it fire off during a hot start, I push mixture in fairly quick and it quits. Prime a little and it fires up fine. I wonder if running boost pump would get enough fuel flowing quicker to keep it going during the mixture push?

Also do you guys push mixture in slowly or quickly? I quickly switch over to pull throttle out to keep it from revving so high. Of course I have been following Lyc manual and setting throttle half to full open during hot starts.

For reference. I have standard Vans engine and fuel servo. I only burn 100LL.

Wayne, I set the throttle so that it will be about 1500 RPM +or-. I move the mixture in at a moderate speed when the engine starts running and I find that being ready to turn the boost pump on as the mixture is pushed usually insures that it keeps running. The only thing I do differently than David Brown is that I have not been immediately pulling the mixture back to a ground lean position. I usually wait just a bit until I am sure the engine is going to keep running before ground leaning. I am going to give David's methodt a try next time I have to start it while hot.

David,

Maybe you think I pull it back really quickly, that may not be exactly what I do, it does not matter either way, I just d not leave an engine fully rich or half rich.....in an agressively leaned state you can't take off with the mixture set that way. If you only have it leaned a quarter of the way and forget you take off in detonation city!

So I think you are doing it perfectly. If you wait a few seconds and lean aggressively and slowly so you do not kill it again, all is good in the world.

After a while you just "know" where to yank it back to.

Your method is exactly the same as mine, maybe I just do it all a few seconds quicker.........but hey, this is the human RACE

Ground lean for me is about 1" out. At this mixture setting it hesitates if I push throttle forward. Now it is just automatic after startup and after landing to lean it out. Plugs clean as a whistle at 25 hrs. That was with all of the rich break in too. My field elev= 663'. You guys are a big help.

Wayne I appreciate you are doing an OK job of ground leaning, but please get out of the habbit of using "rules of thumb".

At a high altitude this may not be such a give away

I strongly suggest that you lean on the ground as I explained, thats all the way till RPM rises and then just tsarts to fall.

This is ALWAYS the right amount, and it will vary depending on where you are and the day.

Think about it for just a minute or three

Cheers

DB



PS: and what if someone else is learning from you? 1" for them may be really bad. If you did that on my quadrant it would not be a good thing. However if you stick to the scientific method, you will only teach good habbits to others and not start more OWT's etc.

I understand that I will need to lean more at higher elevations. This gets me close enough for ground operations at my home field. At such low power settings the engine will not be damaged if slightly richer than the perfect lean and it will quit if I over lean. Pulling the mixture until it starts to die then richen slightly works too and I don't have to look down at the EFIS. Different methods just like in starting. I will try your way too. Aviation and hvac is just full of "rules of thumbs".

I use the engine monitor's lean page in flight, so no rule of thumb leaning upstairs. Thanks for the advice.

Great Wayne!

It is never about engine damage at low settings, it is all about if you forget to go full rich at takeoff, and some day someone will. I have seen it myself!

Teaching good habbits rather than a rough rule of thumb has to be better.

Also here is another tip when Leaning to a LOP setting, either use a Big Mixture pull and then use LEAN FIND to see which one peaks first, then back off, or use the old method and then from the lean side do it again.

You might be surprised at the different result.

The lean find functions seem to be a bit behind the pace some times and I find more consistent results by getting way past LOP, then set the Lean Find, sneek up on peak of the first one, turn the Lean Find off even just note the EGT and lean back, 10LOP or 40LOP etc depending on the power setting or power I want.

A few other tricks deployed with Carby fixed pitch engines seems to make it better this way too!

RV10inOz said:

............... A few other tricks deployed with Carby fixed pitch engines seems to make it better this way too!

Click to expand...

Are you saying you've had success with LOP ops in a carbureted engine? If so, please share the technique(s).

Pete,

I sound like a cracked record but you guys who live in the USA and have never done an APS seminar amaze me. The very best of education right on your doorstep, under your noses and yet most will not take the trouble to attend.

There is one in July a bit before Oshkosh by the way.

The secrets are in education, I could tell you that I have been running an RV7A of Jamie Lee's LOP, and he does now too. It has an O360 and Catto prop. I have run and shown an RV6 owner with O-320 and Sensinich the same (it ran better) and it had nothing but a single EGT and CHT. I can quote you others as well, but I think you get the point.

Al lot of this comes down to experience and understanding along with clever use of carby heat and an engine monitor. What concerns me is that some folk will try to make rules out of advice and then complain when the rule does not work. So anyway, here goes.

1. You may have such poor F/A distribution you will never get acceptable LOP ops. If you are unlucky, well check all these first before giving up. Intake leaks, Spark plugs gapped 0.016-0.018 and less than 5000 ohms. Check timing is in spec.

2. Fly a ROP power setting at cruise altitude and watch the EGT numbers for spread, this is the only time EGT spread really means anything. Using increasing amounts of Carby heat watch for the spread to change and note when the change results in the lowest spread.

3. If you have a Carb Temp, take note of this. This is your target carby temp for ALL future operations. If you do not have a carb temp you need to use this method each time to find the right temp given the day and OAT etc.

4. Lean like you would an injected engine, probably best to get them all over peak and a fair bit, even if it is rough, then sneak up till the first one peaks and then back off from there. With a FP prop the egt numbers will go all over the place so its not easy.

5. if all of your CHT's are less and youhave not lost massive speed you will be about right.

There is always a slight and i mean slight harshness, not roughness when LOP, this is cycle to cycle variability and is normal, even when ROP it is happening, you just do not know it!

http://www.advancedpilot.com/

DO the APS course online or do the seminar. The online course will help you hugely understand what is going on.

Thanks for the info. Any difference in technique or outcome with a C/S prop?
My engine setup is clearly too basic at present. No Carb temp, and no multiple-cylinder CHT/EGT. Looks like an engine monitor in my future.
What fuel-flow difference do you experience from ROP to LOP in carb. engine, and how much speed do you lose?

Pete

.......Not sure I deserved the finger-wagging in your first paragraph just for asking an honest question, however.

Hehehe

Finger wagging applies to everyone, you too Seriously, we spend all this money on aircraft avionics headsets, flying lessons Instrument ratings and yet nowhere in our training is this stuff covered, and worse still the opposite is true, we learn garbage.

I speak from experience, it took me years to work it out too.....except I am half the planet away from the APS guys.

Anyway, you will notice even my harsh comments are meant with good intention or humour.

OK CSU's, the RPM being stable helps, as RPM changes Mass Airflow changes, fuel pumps and flows alter a bit and so the "moving goal posts" make it fun.

My crystall ball says EMS-D10 could be the answer

Fuel flow, well that depends on what you are doing now, but at high power settings ROP vs a LOP it could be 40+ %.

Miles per gallon is the key, and as an example the other day at I think 13000' I did a 10-20LOP Vs 75ROP and it was 20-25% more fuel for about 5% in speed, rough numbers off the top of my head, but as you can see that is a big saving. Down low where higher powers and more ROP you need to be, the margins blow out further.

Doing the APS cousre, you will learn fascinating concepts from the engine curves, and it all makes sense after a while.

Cheers

DB

RV10inOz said:

4. Lean like you would an injected engine, probably best to get them all over peak and a fair bit, even if it is rough, then sneak up till the first one peaks and then back off from there. With a FP prop the egt numbers will go all over the place so its not easy.

5. if all of your CHT's are less and youhave not lost massive speed you will be about right.

Click to expand...

If the induction system is carburetted, won't the small cylinder-to-cylinder variation in mixture mean that even if you manage to get LOP without rough running, at least one cylinder will be uncomfortably close to peak?

I thought that running continuously at/near peak was one of the worst things you could do to an engine in the long term (I count preiginition as a very short term problem ) Maybe it doesn't matter at 65% cruise power?

- mark

RV10inOz

DB knows his engine stuff.
After getting a preview during a Skype session
with David, I will definitely take the APS course
To undo some of my misconceptions about engine management
and get on the "green of peak " bandwagon.

BANG! ;-)

Too lean mix when the engine fired. The BANG came thru the fuel controller, so you might inspect your air filter assy. An after-fire (exh manifold fire) makes more of a POOF sound, or no sound at all.

A bit more 'prime' with the elec boost pump (tho you are NOT actually priming for a hot start - you are only filling the fuel distributor and lines) will help keep this from happening.

When we start the big round motors, we say the BANG is from too much air, and everyone understands that. When those engines actually start, but idle with a blubbering sound, that is a sign of not enough air. Makes sense, eh? It's not too hard to get it right on a regular basis, but each ship, even with the same engines, has a different personality.

You can get 'em bangin' away on descent if you don't adjust the mix as you lose altitude, too. (R985, at least) This causes 'Sore Arm Syndrome' as your wife punches you in the shoulder as the ship sways from right to left (C45) as the engines alternately quit and re-start, all the while bangin' away.

BTW that BANG on start-up lets all round motor pilots in the area know that YOU are buying the 1st round that night. I'll bet I can get all the free drinks I want next week at the Doolittle reunion, as warm weather pilots move to colder weather... Won't happen to me, that's for sure.

Carry on!
Mark

I figured one of my hot starts was too lean as it started right up the second attempt after 3 sec of boost pump on/mix rich. Mine popped on one occasion when I released key switch which allowed right mag to be energized at 25 deg btdc.

How many RV-10/IO-540 drivers have taken the APS course? Approximately how much does it cost? If one leans properly on the ground, takes off full rich at sea level noting egt at 500', lean to maintain that egt until TOC, pulls throttle/prop back to 65% pwr or less, sets mixture for 10-30 LOP(no my injectors are not balanced)...what damage are we doing to our engine? It is not rocket science or we would see more NTSB reports with engines exploding vs loss of control while maneuvering at low level.

I don't know about the rest of you, but I don't have a money tree in the yard and I don't make six figures. At $6/gal fuel, hangar rent, insurance, taxes and a family that sacrificed alot to become debt free at 38 yo, then obtain ppl and build an RV-10...we are taking some well deserved family vacations! I may regret it later but sorry, no APS for me for awhile. Contrary to what the average person thinks...most GA pilots are not rich and few EXP pilots are or we would have just bought a private jet and professional pilot to fly it.

Wayne,

I am more than impressed on your finnacial model, and like you debt free etc at 43 I was not quite as quick, mind you $250K in school fees etc might have sped the process up a bit, but I digress.

Your operation is fine and fuel saving, mind you it could be refined a little. Who says you must use 65% or less? Why not 80% at low level and run LOP. Just make it 40-60LOP though. Most efficient is WOT, then pick an RPM that suits, then lean.

HP is mass airflow on the rich side, and fuel flow on the lean side.

What I can see here is you are operating just fine, but according to a set of "Rules of Thumb", and while that works, and is great, how good is your understanding? Mine is at the point where I know a darn lot more than I used to, but I realise now there is a darn lot more I want to learn. And who knows where it will end. I am amazed at what I once did not know, and even now I am not sure what I still dont know.

So, you and your family are cruising along over the Rockies at night and fat dumb and happy at FL140 and the lowest safe is no much below that, kids playing angry birds on their ipods, wife looking at the pretty stars and moon, few whisps of cloud creating an awesome picture.

You notice a drop in egt on Cylinder 5 and a few seconds later a CHT climbing up. You set your red line CHT at 500F because that is the Book Limit. The alarm will not go off for ages if it climbs that high, but luckily you happened to see it.

What is happening in Cyl 5 and what should you do?

YOU HAVE LESS THAN 60 SECONDS TO ANSWER THIS.

If you do not know exactly what to do, please invest in $395, don't do it because I said so, don't do it for your own ego or whatever.....think of your lovely wife and children who just died in this mind flight.

Some of you may find this a bit alarming and confrontational. But I gave a lecture just last weekend, and much to my surpise a guy in the audience had this exact thing happen, just over water not the Rockies. He had a certified aircraft with only one single EGT/CHT. By sheer fluke he did the right thing. He was 60 seconds away from going swimming in a rather shark rich environment. His engine just lived long enough to make a small sandy strip on the island closest to him.

He had a 1 in 4 chance those probes were on that cylinder, otherwise he would never have known.

He is now pricing up an EMS this week. Or so he promised.


Disclaimer: I have no financial interest in APS or any of the affiliated companies, I tuned my own injectors, made my own turbo injector rail kit, and apart from being a student of Data Backed Science which the APS guys have been promoting for years, and an APS student, and a life long student, that is it. I do have the benefit of being an engineer, in mechanical and electrical, raced cars and built my own race engines. I am not more than a blip on the radar of George Braly's knowledge base, but I do strongly believe my safety is infinitly enhanced by being a life student of theirs and the science of combustion in aero engines.

If the induction system is carburetted, won't the small cylinder-to-cylinder variation in mixture mean that even if you manage to get LOP without rough running, at least one cylinder will be uncomfortably close to peak?

I thought that running continuously at/near peak was one of the worst things you could do to an engine in the long term (I count preiginition as a very short term problem ) Maybe it doesn't matter at 65% cruise power?

Click to expand...

Mark,

Good questions, first preignition is a short term problem, and will kill your engine if not addressed pronto. Preignition has nothing to do with peak EGT, what you may be worrying about is Detonation, and this is a really interesting thing, mild detonation is actually not that harmfull, Chieftan engines operate there a lot of the time, and it keeps cylinders and plugs and valves nice an clean, medium is not so friendly, and raises cylinder temps and if it gets worse, extreme detonation can get away.

At 65% power it is not likely you can create detonation at all. So the question is this, which side of peak egt is it easy to mishandle the mixture knob to create detonation........Answer is on the Rich side. Go look at the graphs. And you will need to be at a higher power than 65% to do it.

You should watch the dyno computer graphs at GAMI when George induces detonation. Quite impressive.

I thought that running continuously at/near peak was one of the worst things you could do to an engine in the long term

Click to expand...

At or near peak EGT is a good and valid place to be, especially when on the Lean side of peak, heck slightly ROP in the FL's is quite good too, but you burn a lot more fuel for the extra few knots. I did this the other day just messing around, FL130 and I got no more than 5% more speed for I think 25% more fuel.....what do you think I did after that litte game?

The secret is not running high power such as up the beach at 500 feet and full bore while leaned to between 40F LOP and over peak to say 75F ROP and byond down to about 180-200F ROP. Why? because that is the zone where detonation is likely to happen. I have seen this on my EMS, its not hard to do.

If the induction system is carburetted, won't the small cylinder-to-cylinder variation in mixture mean that even if you manage to get LOP without rough running, at least one cylinder will be uncomfortably close to peak?

Click to expand...

No, if you are in a cruise at say 7500 feet, WOT, and with a carby engine and even a fixed pitch prop the RPM will end up back at 2350-2450 onve LOP, the last cylinder over the fence might be only at peak or just 5F LOP, this is perfectly valid. Funny enough this lines up with about the old 23/2300 rule of thumb, and all is good.

With this setting if you have a fuel flow of 7.85GPH (29.7LPH) or less you will be LOP.

Now how can you tell? Well consult the curves from APS, look at what the CHT will do once LOP, it will drop, so if you saw the last cylinder start to drop it must be over the hump! RPM will have fallen from say 2450 to 2350 due to HP falling, and the airspeed will have dropped accordingly. All the info is in front of you, you just need to know what it is actually telling you....... did I ever mention education?

So how do you get a carby engine LOP? Well most will just. Some installs better than others, a trick is carby heat, the atomisation in your carby is far from perfect and every bend it goes around the heavy drops tend to not want to be a flowing gas, the best way is to use carby heat that generates the OPTIMUM air temperature for your engine. No two installations are the same so chances are no two optimum temps will be either.

So how do you find this spot? Set up ROPmaybe even at 75ROP at 7500' minimal harm there, and look at the difference between the egt numbers, or EGT spread. This is the only time EGT spread is useful. Now slowly introduce carby heat until you see the EGT spread get to its smallest difference. If you have a carby temp probe, take note of it.

Once you have this temp noted, just use this in flight at any time, altitude, or OAT and apply heat until you get this carby temp. Your egts spread should be at its minimum now, so you short cut that process, now lean to LOP.

If you do not have a carby temp to short cut with....too bad, you have to do the find minimum egt difference each time.

If you do not have an EMS.....buy one.

Having said that I get an RV6 with O-320 and FP prop LOP quite OK with no EMS.....but it takes practise.

So there you go, all the secrets out of the bag.

Now as for my post above, this info and a whole heap more, and a thorough understanding of cause and effect await you, but do not nickel and dime your education. Your life one day may depend on it.

All the best,
David Brown


PS.... I better do some work now.....gotta earn a crust some how!

RV10inOz said:

So, you and your family are cruising along over the Rockies at night and fat dumb and happy at FL140 and the lowest safe is no much below that, kids playing angry birds on their ipods, wife looking at the pretty stars and moon, few whisps of cloud creating an awesome picture.

You notice a drop in egt on Cylinder 5 and a few seconds later a CHT climbing up. You set your red line CHT at 500F because that is the Book Limit. The alarm will not go off for ages if it climbs that high, but luckily you happened to see it.

What is happening in Cyl 5 and what should you do?

YOU HAVE LESS THAN 60 SECONDS TO ANSWER THIS.

If you do not know exactly what to do, please invest in $395, don't do it because I said so, don't do it for your own ego or whatever.....think of your
lovely wife and children who just died in this mind flight.
Some of you may find this a bit alarming and confrontational.

Disclaimer: I have no financial interest in APS or any of the affiliated companies, I tuned my own injectors, made my own turbo injector rail kit, and apart from being a student of Data Backed Science which the APS guys have been promoting for years, and an APS student, and a life long student, that is it. I do have the benefit of being an engineer, in mechanical and electrical, raced cars and built my own race engines. I am not more than a blip on the radar of George Braly's knowledge base, but I do strongly believe my safety is infinitly enhanced by being a life student of theirs and the science of combustion in aero engines.

Click to expand...

First, remember to fly the plane. My wife will have the nrst airport page up on the 496 and select "direct to" our chosen landing site. I will select gps2 on my grt and turn towards it. At the same time thinking of the possibilities...

1. Detonation- reduce power and enrich mixture, land as soon as possible.

I have my cht alarm set at 435F. I will try to avoid flying over mountains at night, plan night flights with a full moon, always have 2 hrs+ fuel on board and fly as high as possible.

I actually like scenario based training. I know you are intelligent. I have not met a builder or pilot yet that I have not learned something from. We all have to be somewhat sharp or we would not be building, flying or dreaming on vaf. I just was getting the feeling that maybe you were not allowed to share what you have learned about engine management with us and were pushing APS quite often. I do appreciate all of your advice, no matter what tone you use(always wearing nomex).

Wayne, I make no apologies for the tone of my posts, often the reader inserts their own perception of tone. The big problem for forums like this. Mind you, protecting your investment and family is no time for politically correct stuff either.

As for the protecting what I learned, there could be an argument that if I had paid for (and attending Ada from here costs me way more than you) an education, why should you and others get it for free. That sounds fair right? In fact I actually do think that is a fair call, but given the knowledge is out there anyway, and George, John and Walter share it all openly anyway, its no big deal.

The Big deal is in one or two posts on VAF I can not do anything like the educating they do in a weekend. Simple as that.

The thing is, all I can do is show you a glimpse of what you do not know already and open your eyes / mind to the world of more training and understanding. Right now neither you nor I can be sure if you REALLY understand something I posted. In a open classroom with real engines on a Dyno.....you will understand.

That is the reason I push the APS courses so hard....I know first hand....I learned heaps through my own self study and my own experimenting, with an engineers mind and some good gear, but until I understood stuff from grass roots, the rest was all just stuff I read about. I reckon I only know about as much as george Braly has forgotten, so I am not the end of the story, just a beginning.

Now back to the quizz...........understand this, I am going to be harsh on you, OK.....but for good reason, you might see why at the end.

First, remember to fly the plane. My wife will have the nrst airport page up on the 496 and select "direct to" our chosen landing site. I will select gps2 on my grt and turn towards it. At the same time thinking of the possibilities...

1. Detonation- reduce power and enrich mixture, land as soon as possible.

I have my cht alarm set at 435F. I will try to avoid flying over mountains at night, plan night flights with a full moon, always have 2 hrs+ fuel on board and fly as high as possible.

Click to expand...

Let me tear this apart into bite size pieces, remembering the scenario I gave you. No applying any of your own twists to it

1. Hitting the NRST and going there is great, takes about 5 seconds to do all that stuff out of the 60 you had. Remember you are over the middle of the Rockies and no airports for a really long way.

2. Detonation: WRONG DIAGNOSIS, I said falling EGT and rising CHT (and fast just like detonation)
Reducing power is not possible or very limited, given where you are and the Lowest Safe, you need as much power as you can get, and 5 out of six are working well.
Land as soon as possible: Well that is a no brainer when you hear the answer and I would say you are 100% right, but you only have 55 seconds left before you are engineless.....and well you know it might be 30 minutes to the nearest airport.
Enrich Mixture: yeah but how much? at 14000 feet how much? Do you do just a little and see what happens, or do you go full rich and put up with an engine that under performs and coughs a bit due way too much fuel?

I have my cht alarm set at 435F. I will try to avoid flying over mountains at night, plan night flights with a full moon, always have 2 hrs+ fuel on board and fly as high as possible.

Click to expand...

Lets deal with this one for a bit, If you had not noticed the EGT drop and CHT rising, and you were looking at the moon and stars, then your alarm goes off at 435, by the time you actually look closer at it its racing through 450, and by the time you do the NRST......you have a failed engine

Wayne and anyone else reading this, please, PLEASE set your alarms at 400 max and if they have a yellow at 380. There is no down side to doing this and only upsides for doing, it buys you time, so no arguments whatsoever please.

I agree, avoid the Rockies at night and fly as high as you can etc etc etc, but that was not the mind flight was it But I am glad we all think that way. There are times when I am over far more remote country at night down here than you guys can imagine, so its a big deal.


So back to the answer: I think you saved yourselves, but I am not sure. You had 60 seconds before it all went pear shaped, and an outlanding up there would most certainly not end well.

Had you said GO FULL RICH.........I would say yes you were saved. Pulling back power might help, but you could not afford that, or not much anyway. Drifting down is not much better when its a rocky cliff.

So what causes a falling EGT and a rising EGT? A broken ceramic on a spark plug and a chunk falling off, Pre-ignition sets in. That spark plug is now a glow plug and the only thing that will stop it is an overly rich mixture that the glow plug cant get the charge away under "preignition terms", yes it may run a bit rough from overly rich but it will run, and the damage done will hopefully be not to sever to last another 30 minutes.

Of course on the lean side of peak you could make the mixture so lean it stops too.......hehehheheh but so will all the other cylinders And that is only an option in a Baron or similar twin.

False diagnosis is just as bad as no idea. Can you be correct all the time, probably not, but the education you get can help. If nothing else it can save you money over time.


By the way, I was running some engine health classes on the weekend at a major national fly in, mainly about Leak Downs, Borescoping and EMS's and education, so I asked the audience at the beginning about that mind story, and came back to it later, and gave them a minute to tell me what to do before they killed me .......one bloke saved my bacon. He said full rich, and only because he had this happen to him. He had a single probe CHT/EGT and was just lucky the preignition event happened on that cylinder. He had no idea what was wrong but just went full rich. He made it to a sandy airstrip on an island close by. One cylinder was toast, but it survived long enough. He only just caught a glimpse, it took not long at all. He had a broken ceramic.

I was amazed I had someone in the class that had this event, salvaged it correctly, not knowing why or how he did, and did not end up being shark food. He is now a big believer in engine monitors!


So again I say.........we do not know what we do not know, me included. There are many more things like this an EMS can tell you, even just maintenance things, so I reckon a small price to pay, and a likely payback.

Cheers!
DB

Posts like these make us think and study

Instead of just staying current, I want to be proficient in my -10. Back to the OP...proficient at hot starting my engine too. Sorry about the thread drift. Thank you for the learning experience DB and others.

Going to Osh this year David???

Wayne, I admire your commitment to not just be current but be proficient. I strive the same, few hundred hours, IFR and accept all I can learn and nothing but the best. Glad you do too!

Yes going to Oshkosh We can even practise hot starts at that time of year!

Would love to catch up, share a coldie!