Forced Landing trouble check drill

[Centaurus]

During the forced landing engine failure trouble check, do you agree that part of the trouble check (assuming a mysterious failure) should include operating the primer (Cessnas and Warriors et al) then try a re-start?
I notice that in all manuals that I have read on the subject of practice forced landings without power, there is no mention of using the primer as part of any attempt to re-start in flight.

[Tinstaafl]

I included it in trouble check drills I taught ever since I saw how an unlocked primer can stop the engine.

It occurred on the ground with a student once but I'm bright enough to extrapolate! :)

[tacpot]

Centaurus has asked an odd question, and then gone on to cloud the issue with an even odder comment (IMHO)!

I don't agree that operating the primer as part of your investigation into the cause of the failure is a reasonable thing to do. As Tinstaafl says, operating the primer is likely to lead to the engine STOPPING, not causing it to burst back into life following a mysterious stoppage. If fuel starvation was the cause of the stoppage, I think it highly unlikely to primer could suck any fuel in (where would it suck it from) - and if it did manage to suck in some fuel, so what - the only impact would be to supply a drop of fuel to an engine that has stopped because it has run out. If you operate the primer quickly while the engine is still coughing and spluttering it, will just cough and splutter some more and die about one turn of the crankshaft after it would have died if you had not operated the primer. So no gain there, and if you operate the primer after the engine has died, you just get a primed engine. The action would not, in my opinion assist with the fault diagnosis.

Centaurus' odder comment was that use of the primer help, or indeed be needed to, re-start an engine after it had stopped. I think this very unlikely unless you have spent ages descending and the engine had got cold like wot it is in the morning.

[Tinstaafl]

Ensuring that the primer is locked helps with fault diagnosis. If an unlocked primer is the cause of the stoppage then correcting that problem may be all that's needed to restart the engine.

[Chuck Ellsworth]

Im a bit puzzeled about how an unlocked primer can stop an airplane engine in flight.

Can anyone elaborate on what make of engine this phenomenom occurs with and just how this can happen?

..............

:) The hardest thing about flying is knowing when to say no. :)

[Don D Cake]

AFAIK an unlocked primer will allow fuel to be drawn into the engine cylinders through the priming system and cause an over-rich mixture.

[Newguy]

Cat Driver.
This can happen to engines in most training aircraft, certainly Lycoming. If the primer is out during flight too much fuel is drawn into the carb causing a 'rich cut', too much fuel and not enough air for proper combustion.

[Chuck Ellsworth]

Buster:

O.K.... however I have never experienced such a failure in flight. I have experimented with unlocking the primer to see just what effect it has and it can or will run rough, however with the throttle in the cruise position I have never experienced a complete loss of power.

Don't get me wrong I am not saying it won't happen on some engine, carb. setups, I just never experienced it.

Another observation... with regard to a primer becoming unlocked in cruise flight, that would be a remote possibility, because if it was not properly locked after priming for the engine start it would in all likelyhood unlock either during taxi ( where it can definately stop the engine ) or during the take off climb segment of the flight.

Any further ideas on my comments? Cause I sure as hell do not pretend know everything about airplanes.

................
:) The hardest thing about flying is knowing when to say no. :)

[Newguy]

Cat Driver
The fact that an unlocked primer can cause rough running is good enough for me to make sure that it is locked when I have an engine failure. It may not be the primer that has caused the problem but the idea of the engine failure cx is to eliminate all the possible causes,or hopefully find the problem. As you say it is only a remote possibility but for all the time it takes its worth checking. Even if it had been locked, the locking pin could have broken!!! ok so that really is a remote possibility but we read strange things in accident reports all the time.

[Don D Cake]

A quick Google using "primer unlocked accident" found these easily.

<a href="http://www.canard.com/ntsb/LAX/88A050.htm" target="_blank">accident 1</a>

<a href="http://www.canard.com/ntsb/FTW/89A017.htm" target="_blank">accident 2</a>

<a href="http://www.eagletribune.com/news/stories/19991114/LN_005.htm" target="_blank">accident 3</a>

It's enough for me to make sure the primer's locked and stays locked....

[Newguy]

Cat Driver, I forgot to mention, if you've pulled the primer out in flight to check what happens, you're a braver man than I.

[Chuck Ellsworth]

Hey guys:

I was not suggesting that checking the primer was incorrect after an engine failure, I was merely pointing out that a primer is extreemly unlikely to cause a complete loss of power.

Continental 0-200's are generaly primed into the intake above the carb as I recall. Lycomings generally are primed straight into the cyl. heads , it varies on the engine how many cylinders are primed.

So to reiterate, all I was doing was trying to clarify the cause of a complete engine failure in flight. To be more precise when instructing students in forced landing procedures we are normally at a sufficient altitude to complete all nessary checks. The only exception would be an engine failure right after take off, going through a lenghthy check list would be the last thng you would do in that case.

The three accident reports that were posted reinforces the point I was trying to make. Unlocked primers do not result in complete engine failures.

As to my unlocking the primer in flight why should that prove to be problimatic?

..........
:) The hardest thing about flying is knowing when to say no. :)

[Tinstaafl]

Because it will change the mixture. Depending on circumstances eg throttle & mixture settings, Density Ht, Carby Ht/presence of intake icing etc it can be enough to give you an engine failure.

As for checking it immediately after take-off, I think we have a difference in terminology/procedures. What I give below are very generalised & often change depending on a/c type.

Vital or immediate actions: Things to be done as soon as an engine failure is recognised

*Carby Ht: ON
*Mixture: RICH
Fuel pump: ON
Fuel: ON or change tanks

Then:
*Pick a place to land & establish a flight path to get to it
*Get a MAYDAY broadcast
*Look after the pax

Troubleshoot checks:
In a nutshell try everything else that might get the engine running.
*Recheck the vital actions (in the initial...erm... 'excitement' it's easy to mis-select something.
*Try each mag. in turn
*Primer: Locked
*Exercise the throttle
*Exercise the mixture

So, in the EFATO primer isn't appropriate BUT in other cases where there is time to troubleshoot then it is.

Hope that clarifies things a bit.

[Chuck Ellsworth]

Why, oh why, do I get myself into these discussions on the flight instructor forum????

I guess I will never learn.

Tinstaafl..... my last question on my last post was rhetorical, if you would read one of my first posts on this subject you will note that I only commented that I have unlocked the primer in flight to demonstrate to some student somewhere in the dim past that the engine would run excessively rich and lose power, it would not however quit completely.

I will once again confess to being my own worst enemy by even trying to comment on an instructor forum.

From now on I will desperately try to be less opinionated about flight training. <img src="wink.gif" border="0"> <img src="wink.gif" border="0"> <img src="wink.gif" border="0">

.................
:) The hardest thing about flying is knowing when to say no. :)

[Tinstaafl]

[quote]...I have never experienced such a failure in flight. I have experimented with unlocking the primer to see just what effect it has and it can or will run rough, however with the throttle in the cruise position I have never experienced a complete loss of power.<hr></blockquote>

Later you refer to teaching PFLs.

No mention of you experimenting with a student on board. Only that you did it.

As for problematic: Isn't the unlocked primer(s) mentioned in the accident reports indicative of 'problematic'?

[Chuck Ellsworth]

OK Guys:

Lets do this once more.

The three accident reports do not state that an unlocked primer caused the engine to stop. Except for report #2 which suggested that excessive fuel burn led to fuel exhaustion over a period of time not stated. The unlocked primer was noted as maybe a contributing factor to running out of fuel.

Report #3 is pure rubbish, just read the idiotic descriptions of the probable cause and check who wrote it.

Several 0f you claim an unlocked primer will cause a complete stoppage of the engine.

Please tell me when this has ever happened.

For what it is worth the last time I instructed at the PPL level was some time ago, however it seems to me that a lot of flying instructors make the most basic things into bigger issues than they really are.

Anyhow guys show me proof that an unlocked primer will cause a complete stoppage of an engine on these basic trainers.

................

[Tinstaafl]

As I said in an earlier post: I saw an engine stop on the ground due to an unlocked primer. How much more 'proof' does one need?

[Chuck Ellsworth]

Tinstaafl:

From your profile it is difficult to determine if you are a licensed, working flight instructor.

In any event I had assumed you and I are discussing the an unlocked primer causing a complete engine failure in flight in the air.

Then this morning I went back and read all the posts on this subject and I note your opinion is based on that you can extrapolate.

Flying instructors have a duty to teach and pass on information based on facts, not their ability to "extrapolate" in the discussion we are having regarding unlocked primers the facts are that a light aircraft engine such as for instance the Cessna 150 can stop at idle RPM on the ground, however the stoppage could also have been attributed to carb. ice something that is normal for this engine..Cont. 0-200.

Once again I stand by my statement, a unlocked primer will not on its own cause a complete engine stoppage in flight under cruise power, where I came into this discussion.

Please do me a favour and find positive proof that shows my statement to be incorrect.

Now I hope this will end this discussion and you have a nice day.
<img src="wink.gif" border="0"> <img src="wink.gif" border="0"> <img src="wink.gif" border="0">

..................
:) The hardest thing about flying is knowing when to say no. :)

[Newguy]

Cat Driver,
I hav'nt read through all the previous post's but from memory I dont think anybody has said that an unlocked primer WILL on it's own cause an engine failure. What we are saying is that it MAY cause engine failure and that, if for example the mixture was already to rich this possibility is increased. As you have stated, at idle power an unlocked primer CAN cause engine failure. Why temp fate by pulling it out in flight?. Does it demonstrate anything to the student that you cant show them on the ground?.To get back to the origional question, which if I remember was should we check the primer after an engine failure, I think we are all agreed that it can at least contribute to a complete failure so YES we should check that it is locked as part of the restart drill.

-------------------------------------------------
stop animal testing
use taliban prisoners instead

[Tinstaafl]

And our duty as a flying instructors is to ensure that we teach in accordance with the a/c manual.

Cessna & Piper both specify that the primer is to be locked prior to take-off. Not one of their inflight procedures specifies the use of the primer with the possible exception of an inflight restart. Don't have access to a manual to check...

Cat, to answer your (unspoken) query. No, I'm not now an instructor. I last instructed in 1999, having instructed since 1989. My instructing experience ranged from aero club to airline college; PPL, CPL, IR, night, multi, instructor, aeros and CFI positions for schools that taught these. There were also a few test approvals that came with the CFI jobs.

[Chuck Ellsworth]

Buster Gonad:

Hi again. <img src="wink.gif" border="0">

To answer your question, I am not tempting fate by unlocking the primer in flight for the simple reason it is a non event.

However I have another question for all the instructors that read this forum.

Speaking of tempting fate why would you fully feather an engine during flight?

My thoughts on this is that by feathering an engine you have now turned a normal flight into an emergency situation.

What is wrong with simulation of feather?

There that should bring a few comments.

This is getting to be fun when I have nothing better to do.

..................... . :) The hardest thing about flying is knowing when to say no. :)

[Code Blue]

Cat Driver:. . [quote] Speaking of tempting fate why would you fully feather an engine during flight?<hr></blockquote>

'cos - as you no doubt know - TC requires that each ME trainee does an air start or has one demonstrated for real as a prerequisite for the check ride.

I'm sure you can do better! <img src="wink.gif" border="0">

[Chuck Ellsworth]

Code Blue:

If you read the Transport Canada requirements for mulit engine training you will note the wording is fullfeathering and unfeathering procerures must be demonstrated.

I sign that the procerdues were demonstrated, that covers the legality. I do not however full feather an engine in flight for the purpose of training.

Why is it that T/C inspectors do not ask the trainee to full feather in fligtht when they are doing the check ride for the new rating?

. .So those who wish to expose themselves to unnessary risk can feather both at once for all I care, I do not feather in flight unless there is a mechanical failure that requires full feathering.

I learned my lesson many years ago about feathering an engine in flight for the purpose of training. Twice I was inable to unfeather, the first time I almost lost the airplane, the second time it was just embarrassing.

.............. . :) The hardest thing about flying is knowing when to say no. :)

[ 21 January 2002: Message edited by: Cat Driver ]</p>

[Code Blue]

Sorry for the delay - just moving 35cms fresh snow to allow Mrs Blue & Bluettes to open the door :)

TP219E fifth edition para 1 (a) 3. :

"..letter of recommendation must specifically state that the candidate has received in-flight training in actual propeller feathering, engine shut-down and restart and propeller unfeathering procedures. "

I do that part within glide distance from a handy 11,000' piece of asphalt.

As to why it's not a check ride item, like you I can only speculate.

Rgds. .CB

[john_tullamarine]

I read this thread with a touch of bemusement.

In respect of any specific engine, has anyone thought either to

(a) review all relevant engine manufacturer's guidance material ?

(b) email/fax the manufacturer's tech support organisation for further guidance ?

Regardless of the subject under discussion, ought one not consider the following points ?

(a) if one doesn't KNOW the details and operating characteristics/problems of a gadget/system in gory detail (ie at a design, test, and maintenance level), then perhaps one (as a pilot) is better placed to abide with the manufacturer's published guidance material in lieu of inventing one's own interesting techniques ?

(b) following on from (a), there is a principle in various disciplines which wanders along the philosophy of doing no (further or increased) damage .... ie minimising the likelihood of further complicating the problem due to well-meaning, but perhaps technically flawed, intentions.

(c) how does one approach the problem of justifying one's actions in court after the accident ?

[Chuck Ellsworth]

Well, Code Blue lets examine another aspect of this shutting down an engine in flight just to show that the feathering / unfeathering mechanism does work.

Aside rom my contention that you are creating an emergency situaition that did not exist before you shut the thing down, here is another question.

We both know that multi engine training is performed year round in Canada, do you really believe that anyone shuts down an aircooled piston engine at the temperatures we have in winter in Canada? Like for instance Winnipeg at 40 below zero?

Maybe you could comment on what temperature you would shut down an engine? What would be your lowest temp.you would shut down an engine for training purposes?

I do not fully feather and restart any piston engine airplane in flight for the purpose of training. Transport Canada in this instance have mandated a potentially dangerous procedure for no logical reason.

By the way their own inspectors will not ask for a full feather due to the danger involved.

..............

:) The hardest thing about flying is knowing when to say no. :)

[spaceman]

My 2c regarding primers and forced landing etc. My flying school had a c172 that was running like a wooly goat whilst on the ground, and upon inspection it was found that the needle valve from the end of the primer was missing, thus allowing excess fuel in, and rich mixture etc. In flight, it was fine for the majority of the time, just occasionally it was prone to a 5sec or so burst of rough running every couple of hours (that usually seemed to happen at night). Noticed fuel figures were slightly high (around 35 L/hr). Once this problem was identified and rectified, the fuel cons. reverted to a more normal 31-32 L/hr, and the rough running on the ground ceased. Not to say that an unlocked primer will necessarily have the same effect, but I'd expect it to be similar. As for an unlocked primer causing a complete engine failure?? I'd doubt it, but an excessively rich mixture caused by an unlocked primer associated with quite a high density altitude would almost certainly cause partial power loss. Hence I teach my students primer locked as part of a forced landing trouble check (as per the operating handbook!!!!!)

Cheers,

spacey

[SimJock]

For what it's worth, I flew a solo cross country for 40 minutes with the primer in a warrior inadvertently unlocked. I thought it ws locked, but it was stiff to operate and obviously hadn't latched properly. Apart from a bit of rough running, most noticeable at low rpm, the engine operated OK until I came to turn it off at destination and found I couldn't. Even with mixture fully lean the engine just kept turning over so I had to remove the key to kill it. When I reported the problem back at base the FI immediately knew the cause and told me how lucky I had been the engine hdn't stopped in flight.

[Angle of Attack]

Just saw this topic, and thought it would be handy to know that I knew a guy once doing glide descents in a C150 on a hot 30C&gt; day at high altitude, and when he went to apply power there was no response, did the trouble checks, found primer unlocked and power restored, initially rough as guts but he got the engine back, combination of high density altitude, low power, over rich cut occured. I don't agree that just because its a remote possibility the check should'nt be done, it should be because it saved this guys bacon and I knew him personally. As for full engine shutdowns, this topic is like stalls, are stalls dangerous, well YES they are if you do them at 500 ft agl, but they are perfectly safe at high altitude. Same thing with shutdowns, if your doing it at 4000ftagl close to an aerodrome, no problem. I would'nt call single engine an emergency situation otherwise we'd get a mayday call from all those singles flying around the country. So there you go.

[yxcapt]

Regarding feathering of a prop, In the US it is required to be demonstrated on the rating ride. I have my students shut down and restart the engine at least twice during their training. My personal requirements for this is a temp above 40F, 3000 feet AGL and have 2 airports with in power-on gliding distance. I have had to land the airplane 2 or 3 times with the prop feathered (in 17 years of instructing). Wouldn't you rather have a pilot experiance flying with a prop feathered during training rather than by himself during a real emergency. I beleave it's a real confidance builder.

For single engine aircraft engine problems, I use the A,B,C,C method.

A=Airspeed best glide. .B=Best field. .C=Checklist items. .C=Communications.

Check list items: I teach a flow pattern starting at the fuel selector and across the panel and around to the door. It covers everything on the manufactures checklist and then some. You may have to think outside the box to save your backside.

[Chuck Ellsworth]

Yxcapt:

I like your ABCC check list as it starts with the most common cause of an engine stoppage and from there is logical. ( Note there is a difference in engine stoppage and an engine failure due to breakage. )

It is not my intent to say that the shutting down of a piston engine engine by feathering it in flight is excessively risky, I am only expressing my feelings on the matter. As to the benifits of a student looking out at a feathered prop and that will give him/her confidence should they have to shut one down due to an actual failure? Well if they actually have to shut one down I would suggest that looking at the stopped prop would be the last thing on their mind.

I am a little curious about your having to land several times with one feathered, was it due to the engine actually failing or because you could not restart after a practice shutdown?

................. . :) The hardest thing about flying is knowing when to say no. :)

[Checkboard]

I was demonstrating the feather to a student, when he suddenly reached over and pushed the prop lever forward as the prop was approaching the feathered position.

When I asked him why he did this, his answer was "The prop looked like it was going to stop!"

Now he was a highish time single pilot, and single engine instructor, and he had never seen a prop stopped in the air. (ie, shut down a single, and the prop usually keeps turning).

Although he had completed the multi theory, he simply had never thought about or grasped the idea that a feathered prop doesn't rotate, even though he knew that it was turned 90° to the airflow.

Now this might be an extreme case, however it underlines the simple fact, in all training, that actual experience beats all the theory you can lay your hands on.

Every initial twin rating should include a full feather and in-flight restart, and preferrably two - one demonstrated, one monitored.

[ 25 January 2002: Message edited by: Checkboard ]</p>

[Chuck Ellsworth]

Checkboard:

WOW::: you must be kidding that any pilot with an instructors rating never put it together in his mind that a feathered prop means the prop is stopped!!!

Hey you are just kidding us??

Now as to your definitave statement that every new student should be taught full feathering and restart in the air, of course you are as entitled to your opinion as I am to mine.

My reason for not full feathering a piston engine in flight just to show someone what it looks like is based on safety considerations. As to teaching them how to restart, well the need to restart an engine that you shut down because of a failure is more remote than having to shut it down in the first place.

But for the sake of discussion lets assume that you wish to restart an engine that was feathered because of a failure, I would suggest that following the restart check list will in most cases get the thing going again, assuming it will restart.

In the final analysis we each have our own methods and reasons for the way we teach and mine are based on exposure to the learning process and always erring on the side of safety if it does not compromise the learning process.

............... . :) The hardest thing about flying is knowing when to say no. :)

[Centaurus]

What prompted my original post was an incident that happened to me while carrying out stall recovery practice in a C150. The propeller simply stopped turning as the aircraft stalled.

Having quickly sent a Mayday while setting up a forced landing pattern (actually due to lack of suitable landing area on the ground at the time, I had intended to ditch it in a river mouth near some yachts where some delicious babes appeared to be lounging on the deck) - I gave the primer a couple of hasty shoves and then turned the key to start. The engine started immediately and from then on no problem.

Which later made me think it would be a useful Pprune subject. The theory being that if the engine stops in the air for an unknown reason, then a re-start may be feasible providing you give it a prime or two. Thus the trouble check might include a restart attempt.

[Checkboard]

Actually , as part of my instructor rating, my CFI had us deliberately stop the prop on a C150 by holding it in the stall, and then restarting it with both dive starts, and key starts. It was an interesting demo - and inspired great confidence should the same thing happen in flight later.

Cat, each pilot must make decisions on flight safety, and deliberatly feathering a good engine is increasing flight risk slightly - however I would say that all training involves greater risk levels than standard operations.

An instructor's job is to mitigate those increased risks as much as possible, without reducing the training value below an acceptable level. Where you place that line is governed both by regulation and experience.

[Chuck Ellsworth]

Hi again Checkboard:

I don't really have much to do at this time of year and find pprune to be an interesting way to share thoughts and pass time.

So, I would like to share mine on this training thing. We each have our own preception on what is and what is not difficult or risky. For me training is low risk due to the environment in which it is normally conducted, plus you are very well aware that you must monitor the student closely so as to be able to take control of the aircraft in time to avert and accident.

What I find high risk is my standard flying. Risk management is a real concern on long overwater flights at signifigant all up weights well above the aircraft gross allowable. Yes we are legal with a ferry permit but the risk is if one engine quits we will have a drift down that usually will put us into the ocean. Another factor is with two engines we double our risk for the first five hours or so until fuel burn brings our all up weight down to a point where we can continue on one.

There are also many other factors on long flights such as weather especially the ITCZ to contend with so for me training is low risk, it is all a matter of preception.

I do agree that we must mitigate risks when training based on such factors as regulations and experience, for me I will make my final decision based on experience when I feel it to be the safer choice. <img src="wink.gif" border="0"> <img src="wink.gif" border="0"> <img src="wink.gif" border="0">

................. . :) The hardest thing about flying is knowing when to say no. :)

[Checkboard]

Ahhh, No fair! <img src="wink.gif" border="0">

I was thinking about the difference between a "normal" line flight, or private flight (i.e. Take-off, cruise, landing) as compared to a training flight, in which the aircraft is deliberatly flown close to it's flight perameters for training, like stalls, steep turns, forced landings, crosswind operations etc. etc.

Flying long sector overwater ferries, with a legal overload is hardly "normal" for anyone else! <img src="smile.gif" border="0">

[yxcapt]

I can recall 3 single engine landings that resulted from us being unable to restart the intentionaly failed engine. 2 of them where in the Piper Apache and 1 in a Grumman Cougar GA-7.

I've had 3 real life engine failures in piston twins. 2 in the Piper Chiefton (PA-31) One was an engine failure on Departure about 700 AGL & IFR, feathered it and dragged it around for an ILS (mag drive failure). The other failure in the chiefton also had a fire with it. As luck would have it, I was directly over an airport at 7000 feet. Never feathered it, just got it on the ground damn fast (fuel line and turbo charger). The third failure was in an Aztec VFR in cruise less than 10 miles from home (blown jug).

Also had 3 failures in jets. 1 duck through the right engine of a citation right at Vr (VFR). 2 geese through the right engine of a Challenger 604, 200 feet AGL and an Oil pressure relief valve failure in a Falcon 50 VFR over the FAF. Oh, and a precautionary shut down becouse of hi vibration, also on a Falcon 50, descent from cruise, Hi IFR ceilings. So I guess that makes 4.

It's been 2.5 years since the last failure. The only bad things I've seen lately have been in the Sim. I hope it stays that way.

[Ivan Ivanovich]

When you withdraw the primer plunger you suck fuel from the fuel line into a small chamber. By pushing the priming plunger back in, you squirt the fuel down separate piping to the cyclinder inlet ports.

Operating the primer with the engine running is therefore likely to starve or partially starve the engine of fuel. If, IF, the engine is sill running with the primer now withdrawn, then as you push the plunger back in, you are likely to experience further rough running due to an over rich mixture.

Either action can, has, and probably will again result in a complete engine stoppage.

Try it on the ground!

[B2N2]

Yes I'm an instructor.... .And yes I always check the primer and teach to do so.Unless you have a windscreen full off oil and a piston sticking out...then it'd be pretty useless I guess.... .We've had several incidents with people not checking it and stalling the engine either on startup/take-off/landing.

[P-61]

Here is something I was asked to think about during multi FI training:. .If there is a good cross wind from say the right, and only one runway in use then which engine do you shut down?. .(just something to think about, also gets the students thinking)

[Blue Hauler]

Ivan,

To add to your points, I was taught that an unlocked primer caused an alternative channel for fuel delivery to the cylinder; i.e., from the fuel tank, through the primer line, into the cylinder. The philosophy was that each induction stroke resulted in a very rich mixture via that channel leading to engine failure. Hence the need to check the primer is locked during the initial trouble checks.

Cat Driver,

I’m with ‘checkboard’ on demonstrating an engine shutdown and re-start in flight. It is nice for the student to know that the systems work as briefed and that the aeroplane will perform as published. I always include such a procedure as part of the endorsement process. Once saw an unscheduled shutdown due to fuel mismanagement. The engine was feathered to avoid further altitude loss. This allowed sufficient time to properly restart the engine using the checklist. The time taken to reinstate fuel flow to the starved engine was considerable and we appreciated the drag reduction of a feathered prop compared with a wind-milling prop. Better to work at leisure than in haste!

[Ivan Ivanovich]

Blue

Yes, that's right. Once the fuel has been drawn into the priming chamber it is then squirted directly to the cylinder inlet ports. The action of the plunger coming out will of course suck fuel out of the fuel line and into the chamber thus starving the engine. Once the plunger stops moving there is nothing stopping the fuel being sucked directly to the inlet ports (via the priming chamber) as the cylinders move up and down creating a vacuum. At this point, assuming the engine is still running, you will have a highly rich mixture resulting possibly in a rich cut.

Some priming systems are worse than others. On a tomahawk once, I had a primimg plunger work lose about 5mm. This was enough to cause the engine to falter and almost stop. In this case it was more likely that the fuel was entering the cyclinder via the priming lines rather than the carburettor and hence running over rich.