Oracle1

The term was used deliberately and is a parody of a comment by our Prime Minister no less, however the term's usage is totally appropriate in this instance.

cockney steve

@ no hoper I was,of necessity, somewhat simplifying. The vast majority of SEP's are Carburetted and the starting-procedure is , in technical terms, the epitome of crudity....Basically, you squirt a few dollops of fuel into the inlet tract, then crank, thus your induction-air evaporates this puddle of fto oo rich to fire first time, but continued cranking will lean-out as the puddle reduces, to the point where the ratio is right...the engine fires, and typically a sooty cloud of exhaust is ejected as the engine "catches" and the operator resets Mixture and throttle. if, indeed, during this brief period of starting (accelerating from cranking-speed to , say 900 rpm idling......the mixture-ratio is in the "danger of detonation" range, it is unlikely to do so, simply because the engine-loading is so light......no doubt, with the correct laboratory setup and the engine on a test-stand, you could produce this and analyse the real-time combustion events.

For all practical purposes the firing-to-idling phase is so brief, and lightly-loaded, that detonation is not an issue.

WRT to permanent-magnet," high-speed" (a relative term!) starters. They are approved!

Again , you raise a red herring....IF the starter was sufficiently fast to throw-out the impulse coupling, that would indicate that the engine manufacturer thought retardation and impulse were not required at that rotational speed....QED.

Have hand-cranked stationary-engines with impulse couplings and twirled it fast enough to start without impulse....no broken wrist or thumb!....likewise many motor vehicles and the odd few marine engines.
Normal Lycosaurus piston engine timing is fixed and works extremely well, simply because !- the average pilot is not an engineer and would be incapable of operating an Advance-retard mechanism correctly,
2... the engines are, effectively, operated as "constant-speed" devices therefore timing can be fixed and optimised for that speed.

No Hoper

Cockney steve, if you are "flood" starting your engine I would suggest altering your technique which will eliminate the the various issues you are having.
As for this anecdotal high speed starter that is able to rotate the engine at an RPM to lock out the impulse coupling, please supply brand name.

Jabawocky

I see a new topic emerging here. Starting Carby Lycomings!

This as described above has been one of pure bastardry for decades. The primers on the humble carby engines are a source of mostly trouble. Besides the hard starting issue, the risk of flooding, and all that goes with it, there is leaks in the cabin and induction leaks in the engine.

Most of these aircraft have no EMS so the leak in the engine is rarely found, or not found promptly.

Take your simple O-320/360, remove the primer, plug the port and live happy ever after. The start technique is simply start cranking, and after the blades move give a couple of sharp push/pull's through the full movement of the throttle and it will start every time. Hot or Cold.

As explained by Steve above getting the "right" Fuel Air ratio is what it is all about.


yr right
I really do feel that with your vast years of experience you would be a little more perceptive. Creampuff has quite a significant engineering training and some other high level diverse qualifications that would surprise you.

Have you had a go at the 25 question fun test in the free trial on the APS website? I am happy to compare your results with Creamie's in private for you if you like. I am sure he will not mind. It is a Fun Test.

Do you need the link again?

Ultralights

what would be fun? everyone taking the short test, then comparing their results here!! for all to see, and maybe learn!

Tankengine

The most important point to take from Jaba's last post for me is that you start cranking BEFORE pumping the throttle!
I have seen air cleaner fires and damage from the old pump, pump pump, crank. (simple really-inverted carby)
Despite this I have seen the wrong method written into ops manuals.

No Hoper

If you be pumping that acc pump as described you are back at flooded engine, surely?

43Inches

If you have trouble starting an 0-320 D3G in a Warrior it's broken or you're doing something very wrong.

Do not pump the throttle, this only results in an nice bonfire under the engine.

Definitely do not prime with the throttle. As stated above this just puts a trail of fuel dripping out the bottom of the engine ready to light off with the slightest back fire.

The correct amount of prime is basically all that is needed for the conditions.

I know this because I've had to clean up the mess numerous times after Cessna pilots, including instructors jump across to PA28s and try to start them with throttle pumping. My theory is the Cessna 150/152, 172 have a higher speed starter than the PA28 which allows the fuel to be sucked through. The PA28s much slower starter I reckon inhibits much fuel being drawn through until it fires and speeds the process up, so throttle pumping just puts a pool of fuel dripping out the bottom.

Depending on the engine the fuel may not even make it into the engine to flood it, the flooding may occur in an even more undesirable location.

yr right

Jaba
Cream puff can be a rocket scientist he can pack shelves in Walmart for all I care. The response he got is what he deserves. To attack my credabilly I will not stand for. Ask the casa solicitor that tried the exact method to me in court. I made him look like a fool and destroyed him in the court. I will not stand for some one that dose not know me and what I stand for period. Like said I don't care what he dose. And I stand by my record of providing 100 % safety in all what I do in regard to aircraft maintenance. If this don't suit some people here on this forum so be it.
I might add the the org use gstio here dose not do lop. We also have no dramas with our engines. Tcm whilst the basics engine looks the same the manufacture and the materials has changed considerably over the years.

I will also add that I and ever lame can only set an engine to the data that is provided. The pilot can destroy and machine at his will. I and every other lame have know control over that.

Easiest way to start a carb engine is to prime get out hand swing the prop serval rotations hope back in and hit the starter with mags on. It will start every time 1st time if every thing is up to speed. But hey what would I know.
Cheers

Hempy

yr right,
As I read this thread I don't see anyone here doubting your ability to maintain aeroplanes, obviously you can if you've held a job for as long as you have. What I see is people who know more about the subject of engine management than you do telling you that your training is outdated and if you intend to pass advice on engine management to pilots then perhaps you should educate yourself on current best practice first. Keep fixing your planes mate.

Creampuff

So anyway…

On the subject of priming, does anyone have trouble starting CMI engines when they’re hot? Some people have successfully tried the ‘run the electric fuel pump for a minute or so with the mixture to idle cut off, then prime per cold start’ method, but others haven’t tried it or have tried it without success.

I’d be interested in hearing whether people have tried it with success.

T28D

Puff, yes running the pump works to flush cold fuel through the upper deck fuel manifold and distributer valve thingo at ICO, then go for a normal start.


Problem only comes if you then screw up and miss the start, a hot flooded engine is a difficult start without a burn't out starter motor, better to go back inside and have a cup of coffee and start all over again in 20 minutes.

Aussie Bob

Personally I have never had much success running the pump. Two methods I use:

1. Idle engine then stop using the mags (turn off key). Do not touch mixture, leave rich. Then, no prime, start like car, use high prime to keep running. Great for stop/start

2. Use half of normal cold prime then crank while opening throttle. Most will start somewhere around 3/4 open. Pull back throttle, use pump to keep running. Great for a 15 minute stop.

yr right

T2rd

Negative. Once the mixture is placed into ICO no fuel is past to the fuel nozzles at all ie upper deck.

Creampuff

Hi T28D

Not sure of the brand/model engine you’re talking about there. On a bog standard injected CMI engine most or all of the fuel should be blocked by the FCU (being in ICO) and therefore not make it through to the manifold and injectors. (Although the tech data for the FCU does show that a conforming item can still let a little fuel through. It's also different on turbo models, though, because apparently the mixture mechanism is in the EDP, not FCU.)

The aim of the technique, as I understand it, is to flush cool fuel through the heat-soaked EDP (not the manifold or beyond).

yr right

ICO is what it dose at the fcu any leakage that may come out is stoped the a little known function of the spider valve(distribution valve ) it also has a cut off built it to it. but hey you would all know that wouldn't you.
Cheers

43Inches

Never had any problems starting Conti TSIO-360 rich whether hot or cold, unless of course you flood it priming with the pump. I did find sometimes the 200hp ones didn't want to stay started without the fuel pump on occasionally when very cold.

The more important issue is when you stuff up the priming and it doesn't start, then it needs divine intervention to get it going;

sounds about right.

I can't recall if I've used the non-turbo ones.

The funny one was the PA31, I have been told about 50 different starting methods, the one that worked the best almost every start was the one in the book.

yr right

WTF
1. Idle engine then stop using the mags (turn off key). Do not touch mixture, leave rich. Then, no prime, start like car, use high prime to keep running. Great for stop/start




OMG

yr right

Aussie Bobs new book entitled


How to perfectly Hydraulic your engine in one easy step.


Seriously you cant be serious and if you are that you wouldn't let me work on your aircraft I think my later statement of me not working on it is a truer statement.
Cheers

Creampuff

For people who fly behind CMI engines, this is one of many useful on-line articles: Continental's Cram Course: TCM's Aviation Technician Advanced Training Program - AVweb Features Article

Apropos of the function of the manifold on CMI engines, from the article:That’s why you need to take a close look at the bleed vent on the manifold during pre-flights. If there is blue staining, it indicates the diaphragm is damaged.