Engine Failure - Engine Troubleshooting Checks?

[Big Kev]

Hi Gang,

Just been thinking about what we've been taught about the procedures for engine failure and at our school we were taught that after intial actions and choosing a field to go through FMOST checks.

Fuel
Mixture
Oils (T's and P's)
Switches
Throttle

I can understand the changing of fuel tanks and turning the pump on, changes the maggies (maybe due to broken mag teeth) and checking the oil temps and pressures but......

What I don't understand that well is why we go mixture through then range and throttle through the range - surely you'd want the mixture to be full rich right? - so why go in and out with the mixture lever? How can anything get blocked in a fuel control unit?

And why throttle - wouldn't we just want to leave it at 1/2.......not idle as the idle adjustment may be too low to get the engine idling but why not just leave it at 1/2 way - why go in and out like the instructors show you??

Thanks for your replies once again.

[Awol57]

I teach the student to pump the throttle, as most of the aircraft we operate have accelerator pumps, similar in principal to the primer. Any help the engine can get I figure.

Also if the throttle moves real easy, one of two things are your problem, the friction is stupidly loose, or the throttle cable has broken.

[OZBUSDRIVER]

Carburettor uses different jets for different throttle openings. If the main jet is blocked at WFO, adifferent throttle setting can bring a different circuit into play. That and some a/c do have an accelerator pump on the throttle. A C152 doesn't have one.

My EFATO check also had carb ht FMOSTC

[Chimbu chuckles]

Full rich mixture may flood the engine and inhibit restart...by checking across the range of mixtures they are hoping for a fuel air ratio that may work.

Checking the throttle is looking for partal power and/or a loose linkage.

Having said that.

If an engine is running fine one second and then stopped dead a few seconds later, the typical training scenario, one of two things has happened.

1/. Fuel...you have run a tank dry or the intake is blocked. I had an engine failure years ago in a C402a when a bit of rubber blocked the fuel flow momentarily and then fell back before being sucked in again and again blocking the fuel flow. The result was cyclic failure and full power and the aircraft yawing both left and right.:confused: This occurred on takeoff just after gear up.:ooh:

2/. Air...the air inlet has become blocked. A mate was killed in an Islander when the air hose reinforcing (a spiral wire) failed due to corrosion and the canvas tube collapsed under the suction forces and blocked all air flowing into the engine...instant engine failure...high in the PNG mountains at very low level under low cloud he was unable to line up well enough to land and crashed on the assy go around.

So if this happens change tanks and maybe use boost pump on low...not high...keep your finger on the switch so if it catches you can turn it off before flooding the engine and getting a rich mixture cutout. If you have merely run a tank dry or suffered a blockage it will restore power almost immediately in most aeroplanes. Don't change the mixture because it was set ok a minute ago and nothing has changed except fuel flow. Some aeroplanes have header tanks and it might actually take a minute or two to get fuel to the engine.

This sort of failure is just like selecting idle cut off..that's how fast the engine fails...if it fails slowly it may be a blocked air inlet...select alternate air and see if that helps. Carby heat on those aircraft so fitted. Again if that is the problem it will start almost immediately if you don't **** around with other things like mixture or throttle. In both the above scenarios you have merely 'lost' one of the variables..fuel, air and spark. Re-establish that variable and the engine must run as it was before....**** with the variables and you may succeed in not letting the engine regain power or hide the true nature of the failure.

If, on the other hand, the engine is running rough, missfiring, back firing etc the problems are deeper and possibly more mechanical in nature. Yes water in the fuel may cause some of those but having done a good preflight should allow you to discount that.

I once had an engine failure, almost a double engine failure, in an Islander caused by 3 out of 4 magnetos failing. The symptoms were uneven running, slight roughness, small power excursions causing slight yawing left and right and falling EGTs and CHTs. It started in the left engine first and my trouble shooting started with slight power changes...adjusting mixture and throttle slightly to ensure I was not over or under leaned. I changed tanks to see if that helped and it didn't....after about 10 minutes the right engine started doing it too:sad: I was over the sea a long way from land:uhoh: Eventually the left engine stopped and I began drifting down with a not brilliantly running right engine...but as I got lower (I was cruising at 9000') into warmer air the right ran better..it never ran great but the aeroplane stopped descending at 1000' and I was able to crawl along the coast and land at Hoskins keeping various beaches as backup for a full forced landing...the engineers changed 3 magnetos and the aeroplane ran perfectly again...until about 8 mths later when it was crashed on the aforementioned assy go around.

If there is a great loud BANG and then engine stops dead siezed or causes so much vibration you can barely see the instruments you are pretty well fecked...if it keeps banging away you might try partial throttle to see if there is a power setting that sorta works but you are going down so you might as well pull the mixture and concentrate on landing the bloody thing....had one of those too...accompanied by bits of engine exiting the cowl...didn't do any trouble shooting that day:}

The bottom line is if an engine fails after takeoff you have zero time for trouble shooting...just land as best you can. If you have a failed or failing engine in cruise you can trouble shoot and 99 times out of 100 the first thing you do, change tanks, will fix it. pnumonics like '**** Me Im In Trouble' are ok for giving a structure to work around for a new pilot but in my view they useless without understanding.

Go and talk to an experienced engineer and discuss all the likely failure modes for the engine/aircraft combination you are flying...I would bet next mths salary that he has seen the results of every one of them over the years and can tell you what they look like from an engineering standpoint.

As an example a failed throttle linkage generally results in the engine running back to idle and that is it.

Your first priority is fly the aeroplane. I once had an engine dead cut in a C185 while doing circuits with a student. At 800 odd agl you don't have a lot of time...we had been extended on downwind by a backtracking jet and were beyond gliding range to the airport...Murphy's Law. I knew it was either fuel or air but between flying the aeroplane, planning the forced landing and checking the boost pump, mixture, alternate air and fuel shutoff I forgot this aeroplane had a fuel selector as well. The 185 I usually flew in those days did not...and those models of 185s that do, have them out of view between the seats. As I turned finals for a road at a few hundred feet I remembered the fuel selector (which I had instructed the student to put on 'both' during the preflight but had not checked he did...my fault) and wormed my hand down between the seats to find it was still in 'left':eek: Nothing had failed...everything was working exactly as designed:hmm: But at that altitude I knew I had no hope of getting a restart so proceeded to land on the road...After bashing through some power lines:ugh: we walked away with no injuries and little damage to the machine and wore the week or so of merciless ribbing by mates:} Dats life!!!:ok:

On another occassion taking off in an Aerostar 602P at 'MTOW':E I had an engine fire warning coincident with a 'failing' engine...MP dropped right back to an almost useless setting. Again I was at about 100 feet with the wheels tucked away..decision, do I crash straight ahead on really rough ground and probably cartwheel or keep flying? With everything balls to the wall, skid ball centered and blue line nailed I watched the left engine closely...there was no trouble shooting to do...either it's on fire and the wing will burn off or it aint...no bubbling paint or smoke, flames etc issueing forth so decided whatever the problem was I was not on fire...yet. I flew a low fast circuit on 1 and a bit engines and landed...after shutting down I removed the left cowling to find one of the manifolds had come loose from the engine block blowing hot exhaust gasses on the fire probe and causing MP to drop back.

The aircraft owner watched the whole thing from the ground..."Do you want the good news or the bad news?" Good news?..."Yeah...I wasn't really on fecking fire!!!"

But at the end of the day if you cannot take a joke don't play the game:}

[empacher48]

I agree to what has been mentioned here in regards to Mixture. I tend to operate C207s & C206s quite often to 10,000' AMSL (and beyond to 13,000 if the weather requires). And at these heights if your engine fails due to fuel starvation - the flight manual restart technique doesn't work.

A number of years ago two flight examiners in our company took one of our 207s to altitude and purposely turned off the fuel to simulate a fuel starvation event, then using the 6,000 feet available try a number of techniques to ensure a proper start, the one that worked the best was to leave the mixture alone - or even lean slightly. A side effect of this experiment was that with the big turbocharged continental donks up the front, when the engine was starved of fuel there was very little change in engine note due to all engine parts still working from the windmilling prop - there was a noticable lack of performance though.

Although trouble checks are a great way to try and diagnose an engine which has stopped without any real forewarning, usually checking instruments first can tell you a lot eg. oil pressure low and high oil temperature, means you don't have to worry too much about fuel etc. Likewise it can be easy with an instrument check first to see that you've run a tank dry. But if all seems normal with the instruments then it might be time to investigate things further.

As far as engine failures during take off - we tend to operate from hot / high aerodromes, performance is limited (usually when we are hot, we may even have a 5 kt tailwind as well) at any sign of a cough it usually is an instant hit of the High and Low Primer due to vapour lock (some pilots have forgotten to purge the fuel system prior to start), power is usually restored to come back and land again. If the primer fails to work, think quick, keep flying it all the way in!!!

[Sqwark2004]

The acroname (sp?) that I was taught for EFATO's went something like this.

F:mad: K ME I'M TOAST

Fuel
Mixture
Ignition
Throttle

Was always a good way to get the students to remember it.:p

[Centaurus]

Chimbu Chuckles. What a superb example of first class airmanship knowledge. The stuff you have written is a goldmine of information and should be saved in Favourites by all thinking pilots. Many thanks for the info.

[pall]

Chimbu,

One of the best postings I have read! Your extensive experience makes you well qualified to share your wisdom. I wish you were my instructor. Thanks for the post. I will keep it in my theory files.

Have you any briefing notes for emergency proceedures that you use with students that you could share with us keen ppruners?:D

[Ando1Bar]

Big Kev,

If you're the Big Kev I think you are feel free to discuss this further on your flying school's forum. We're more than happy to run your through our reasoning if you're not sure.

The answers above are gold though! :D

Ando

[Ando1Bar]

Just another thought, the FMOST (or like) checks are usually used as 'restart' checks once you've controlled the aircraft and thought about somewhere to land.

The initial, vital actions should be something like:

Adopt the glide speed (lower the nose if taking off)
C - carby heat (or alternate air)
M - mixture
F - fuel - fuel on/both/switch tanks and pump on if fitted. Exact fuel check depends on aircraft type and should be considered as part of the take off safety brief.

Depending on the nature of the failure you might not get through all of these (particularly if the failure happens soon after take off), but should cover most possibilities in a short amount of time. These are also singe engine checks only.

[M.25]

I agree. A very insightfull post by chimbu. :ok:


What I don't understand that well is why we go mixture through then range and throttle through the range - surely you'd want the mixture to be full rich right? - so why go in and out with the mixture lever? How can anything get blocked in a fuel control unit?


In addition to the fact that an engine needs fuel and air to run, it also needs to be at a combustible ratio. If you have a fuel restriction, (the engine is still receiving fuel but at a reduced rate) retarding the throttle might reduce the amount of air being drawn into the engine to a point where the ratio between the fuel and air becomes combustible once again. This might restore a very limited amount of power, which is obviously better than nothing. Similarly if the air intake has been restricted, (assuming alternate air is not available or has not worked) reducing the mixture might bring the fuel/air ratio back into a combustible range, therefore restoring a limited amount of power.

FMOST is a simple mnemonic that instructors use which covers most bases in most piston aircraft in a short amount of time.The best defence in any abnormal situation is to know and understand your particular aircraft - especially the fuel system.

[Chimbu chuckles]

Pall sorry I am not an Instructor....was for a very short while over 20 yrs ago but since my Grade 3 lapsed in about 87, just after I went to PNG, all my instructing has been as a supplemental airline/charter company check and training pilot...mostly in C180/185, Bn2, C402,404,Aerostar in PNG and later as a CASA approved CP/C&Ter on a corporate Falcon jet.

When I retire from airline flying I would like to go back and teach in GA...if there is any GA left in 15-20 yrs.:(

Ask away though...if I can help I will:ok:

[lostpianoplayer]

...having had one real EF, and one misdiagnosed one (ie as a low time PPL I thought the engine had failed when it started making the kind of racket engines make when the exhaust manifold breaks, so pulled the throttle and glided to a landing at a not-so-far airport from 10,000 feet - DUH. Sure wish I'd done the trouble checks then) I have found out one important thing that might be worth bearing in mind as part of this fairly technical discussion:

Trouble checks aside, my experience when it all went quiet was my mind went to toast. It's panic that's the most dangerous, I reckon. Really. When the fear is on, one can forget the simplest things. While the pro's that fly every day are more likely to be highly current and not screw it up, for us PPL's or anyone who doesn't have years and years of intense experience I think it's a good habit to have a simple mnemomic that reminds you of EVERYTHING. Even airspeed control is hard to remember when it's a real engine failure. You just can't believe it - the first response is denial, and the next is likely to be intense fear, unless you're way current. And it's not a big step from controlled fear, which is OK, to panic, which is not. Panic, and you could get so tied up with your trouble checks that you forget to maintain flying airspeed, for instance, and the next thing you know you've got an EF AND a spin to deal with. (Happens all the time). Or worry about your Mayday calls/trouble checks BEFORE you find the best place - or least-worst - to land, and in the process lose the option of a perfectly good paddock cos you're pointed the wrong way, with your head down.

Personally, I use SWLFMRP as a catch-all for all aircraft. (I think Sex With Llamas From Macedonia Requires Patience, personally, but whatever you're into.)

Speed (climb to convert to altitude, or as noted above nose down if on takeoff - whatever it takes), Wind (ascertain/confirm direction), Landing (Plan it, NOW - where, how, high key, low key, all that) Fuel - NOW you switch tanks, turn pump on, off, carb heat if you've got it, Mixture - check rich, wiggle, Radio (if you're gonna crash, hopefully someone will come and get you) and Pax (briefing.)

And I remind myself about those Macedonian Llamas every time I fly. And when I'm not flying. Even when I'm driving, or riding a bike. I think the big thing is to not get too tied up in the trouble checks - if your engine quits, once you've switched tanks and turned on carb heat if you have it, and any extra pumps, the 80/20 rule tells you it's likely not to start. But if you get the landing right, the rest is OK.

All this is a roundabout way of saying I think it's best to stay current with the basics, so current that you have a BOMBPROOF, PANICPROOF mnemomic that'll remind you what to do when it's necessary - which is to FLY the aircraft. Don't lose sight of the fact that when it gets real, your mind can play tricks on you, and it's the - endlessly rehearsed - basics that will keep you alive, much more than all the wiggling on anything moveable in the cockpit - with the caveat that the chances are good that if the engine has quit, you just ran a tank dry. That's my 2c, for what it's worth.

As a slight addendum, now I've practiced it so much, it's SWITCH TANKS, BOOST, CARB HEAT while simultaneously attending to those Llamas. Which was useful one day when I foolishly ran a tank dry on landing, in an aggressive side slip (double duh) - but it was gonna be a survivable glide anyway, cos the SWLFMRP thing kicked in straight away. It's gotta be, like, burned into your subconscious, I think, to ensure it's panic-proof.

Don't mean to subvert a technical discussion. I hope it's a useful thought.

[Chimbu chuckles]

lpp and others.

The main reasons why professional pilots, and particularly airline pilots, are less likely to panic is they have, subconciously, had 100s of engine fires, failures, explosive depress, cabin fires, hydraulic failures, flap/slat assymentrys, jammed stabs, electrical fires etc etc....on top of whatever they have experienced for real over the course of a career.

Every 6 mths when we come up for recurrent training we study all the likely scenarios we may face in the sim...most of us, certainly I DO, sit quietly and 'couch fly' various scenarios...every speed, call, configuration, memory item etc throughout the process from brakes release on the takeoff roll to park brake set and the pax evac if that is the final likely result...and in the sim at least it generally is the likely result:}

We then climb into a simulator and from the moment we sit in our respective seats for the next several hrs we do everything exactly as we would in the real aeroplane....and guess what?

Our SUBCONCIOUS mind cannot tell it's not REAL.

In fact I have landed a simulator after a particularly busy emergency filled LOFT and found my heart pounding and my knees shaking after it was all done.

You can do that too...trick your subconsious and 'condition' your responses to lessen the likelyhood of panic and fear. I learned about this technique donkey's years ago from someone and have practiced it ever since...it REALLY does work.

In jet aircraft we have the luxury of not being in a particular hurry, unless on fire, and the performance that virtually guarantees if we do x then y will result. In large aircraft emergencies are generally a LOT more complicated than in a light GA aircraft because so many things interact with other systems and there are generally large variations in some parameters, like landing distance required, when something is broken or jammed...also if there are 10 different checkies in a company there will be 12 subtley different 'best' ways of coping with a given scenario:ok:

Not an issue in your average bugsmasher...they are all, even the so called 'complex, high performance' aircraft like Bonanzas and C210s, Barons etc, very simple aircraft with simple, and generally very similar, systems....but things happen faster in small aircraft!!!

So having been for a coffee and chat with your local crusty LAME and picked his brains about various failure modes sit down and think up some worst case scenarios in your usual weapon of choice. Having done that sit in a quiet room and simulate it in your head....everything from the daily inspection, if you so chose, to starting the engine, taxiing out, calling ready, takeoff. All with your eyes closed picturing everything and moving you hands and feet as you would in the real aeroplane. That helps develope muscle memory.

Perhaps you fly a C182 regularly out of an airport where a catastrophic engine failure below 500' gives you one chance only to land successfuly on a golf course fairway or ditch in a short, straight, section of river...29 at YSBK was such a scenario when I was learning to fly there 25 yrs ago.

The scenarios I used to run through while flying in the PNG highlands don't even bare thinking about but included force landing C185s on super steep mountain sides...how much speed I would need to get the nose up high enough to mush into 10' high Kunai grass at near zero speed on a 60 degree slope..or what I would do if the engine failed in an Islander before getting airborne at a 300m, 15% sloped airstrip which ended in a vertacle drop into a gorge....there would be no possibility of stopping in that scenario so I 'couch flew' reducing thrust on the good engine to keep straight (highly likely I would be below VMCa) and pushing forward as I went off and regaining speed in a dive before turning and flying along the valley, cleaning up the dead engine and landing at a lower airstrip or force landing in a clearing...usually the bottoms of the valleys were still above single engine ceiling..as I flew in and out of these places all day every day I looked for places where I could maximise my chances of surviving my various 'worst case' scenarios...studied the lay of the land and worked through them looking for holes or traps. It was extreme flying in extreme circumstances (and ****eloads of fun:ok: ) but over time you realise that there is not much you can't survive if you

1/. Fly the aircraft as far into the crash as possible and
2/. Have a plan that means you're not ad libbing as you go.

You have also conditioned your subconcious...it has done this 50 times already...it's a piece of piss!

Smashing the aeroplane up is quite ok...as soon as the catastrophic failure happened it stopped being your aeroplane or the flying school's...it passed into the irrevocable ownership of the insurance company...and who gives a flying **** about them?

So you are sitting in your chair eyes closed doing your runups in the parking bay...trim set, fuel on fullest tank, park brake off, taxi to the holding point, ABC ready! ABC wind 320/10 runway 29L cleared for takeoff....lining up, wind from the right, aircraft rolling straight, full power, T and Ps ok, RPM ok, MP ok, keeping straight, wings level...rolling off the aileron now as we accelerate, rotate gently approaching flying speed...aircraft airborne, tracking the centerline, speed is 70 kts, trimmed...80 feet can still stop in the overrun...150 feet...can make the river now...BANG!!!!! ****!!! can't read the instruments..**** pull the mixture...that's better...lower the nose 65kts....turn toward the river...pull the pitch all the way out...trim!!!!!...Mayday mayday ABC engine failure..landing in Georges river, 2 POB. Got to be down before the bridge...lined up ok...too high..full flaps..TRIM!!! 80'...still going a little long...PITCH!!! ease it forward use it like an air brake...too much...little less...lower the nose...speed 65...trim..50'...open the doors!!!!...speed 65kts...DON"T stall...fly it all the way...10'...keep flying it..all the way down...looking well ahead...trees flashing past...LOOK AT THE TITS ON THAT SKI BOAT!!!!!:E ...2 feet....easing back...easing back...shiiittttt...stall warning... SPLASH!!!!! nose wheel dug in...almost went over...reach for your passengers seat belt sitting next to you release it...release mine...water is up to my waste!!!...push her out the right door and follow...splutter to the surface. heart pounding...aircraft tail towering overhead behind me..starting to sink..SWIM...that ski boat has turned up....LOOK AT THOSE FECKING TITS!!!!!:}

I think you get the picture...pick whatever scenario you want and FLY it!!!!!

I bet as you read the above worst case scenario your hearts beat a little faster as your adrenaline ramped up....that is because you subconcious thought it was really happening!!!...or if it didn't your obviously not a tit man...substitute anatomy preference:}

[haughtney1]

In fact I have landed a simulator after a particularly busy emergency filled LOFT and found my heart pounding and my knees shaking after it was all done
Bloody hell...and I thought it was just me!
Mind you I get that feeling during the brief:E
Ive had two engine failures in my time..both on piston aircraft....
1. The first one was glider towing in a 260hp Pawnee....at about 200' agl Bang pop bang pop pop....and a rather sudden loss of power, the checks that had been drilled into me at the time were F M I I P
I KNEW fuel was on...Id checked it on taking up slack
I could see the mixture was set
A 1/2 second scan of the instruments (theres about 3 engine instruments)
showed all to be normalish..except RPM and MAP
Ignition was on at least
Which left me with power.....I pumped the throttle..and hey presto...a splutter then a bang then a good engine again!
Whilst all this was going on Id managed to aim for my spot (a place I had surveyed many times off this runway..just in case) and managed to convince the glider on tow to bung off with some adventurous wing waggling.
I flew a tight low level circuit and landed crosswind behind the glider. No matter what we tried we couldn't replicate the problem on the ground, my first guess after a time was fuel starvation..as it seemed to match the symptoms. This turned out to be the case, the incorrect grade of fuel line had been fitted during a previous 200hr check and had the effect of slowly dissolving into fuel mix, when a slightly larger piece of fuel-line broke free it blocked the inlets to 4 of the six injectors (Those of you familiar with the direct injection of an IO-520 will know where I mean) so that when I pumped the throttle the combined pressure and scavenging effect of those 4 empty cylinders cleared the obstructions.
The second failure I had was in a PA31 during the cruise (luckily it was almost empty) This particular aircraft was, and still is to my knowledge privately owned..and in this case the good old TIO-540 decided that enough was enough and preceded to drop its oil and attempt to seize. Fortunately I was quick enough to catch it before life got to interesting..and was even able to maintain 5000' :ok:
Its all about flying the aeroplane..before you even bother with checks or trouble shooting...given the time available, I was very lucky to get away with the pawnee problem..the navajo was more of an exercise in trouble shooting and figuring out that the donk had thrown all its oil (not that it was hard..a quick look at the cowling....and then at the oil pressure confirmed it)
Fuel
Mixture
Ignition
Instruments (if you have time)
Power

[Chimbu chuckles]

The great value of simulating stuff..either in a real sim or in your head...is that potential problems get exposed.

In the scenario of a cabin filling with dirty river water after having the wind knocked out of you both literally and figuratively, can you find the passengers belt buckle..how will you find it and how does it open?

What about if you have two young children in the back seat?

Taking the wife and kids for a Sydney scenic with your fresh PPL and ditching in the harbour for instance...there is NO WAY they will manage, you MUST!

LOTS of people have drowned strapped in the seats after perfectly succesfull and survivable ditchings.

[Centaurus]

Keeping in mind of course the simulator can be a two-edged sword in the hands of a maniac check pilot. There is a very good reason why many pilots loathe their scheduled simulator "check". Used as potential career busting device the simulator has caused tears and dread and memories which go back years that some unfortunates will never forget.

When simulators were first introduced into Australia, the AFAP (a very powerful industrial organisation in early years) directed that a pilot scrubbed on the say-so of check captains in the simulator was to be given the opportunity to prove himself in the real aircraft. Of course this severely restricted the antics that could be pulled on the pilot and invariably he passed the actual flight test. This prevented the well known "triple jeopardy" emergencies foisted upon crews in the simulator.who would wonder what the hell the instructor was going to fail next.

[Tinstaafl]

'Fuel....air....spark' is my litany.

If the a/c has fuel selectors then I change from whatever it was on to the alternative.

If it has standby/emergency/boost pumps then they go on

If it has manual primer then I ensure it's locked although I keep in the back of my mind that if all else fails then maybe using it might give me some intermittent power.

If it has a mixture control then it gets moved around, usually starting at full rich

If it has carb. heat/alternate air then it gets selected

If it has a throttle (natch...) then that gets moved too.

If it has magnetos then they each get a go at running the engine without the other one.


etc


Pretty much if it has a knob, lever, button, switch or other device that controls any of the three items then it gets moved to an alternative position.

[csupilot]

What risks are associated with checking the mags? I've been told this isn't always the best idea as it could make the problem worse if the mags are mucking up.

[Atlas Shrugged]

Pretty much if it has a knob, lever, button, switch or other device that controls any of the three items then it gets moved to an alternative position.
Always remember though, not just in an emergency but at any time, if you do something and something goes wrong, undo the last thing you did ;)

[lk978]

Am a fan of the FMOST checks - but in time critical situation it becomes more like F*&k Me Charlie or FMC, the others are a secodary response

[Wombat35]

Hi, Just wanted to add my two cents worth...

Having just seriously started flying pistons again, had something happen the other day that re enforced the importance of thinking about your conditions as a potential indicator as to what may be causing your problems.

We (I was instructin and the Stud was running the checks) were doing the run up and had checked Mags, Carb heat and inst and got to the idle check and the engine wouldn't idle, the RPM just continued to drop and would have stopped if I didn't crack the throttle slightly.

I though, hmm it didn't do this yesterday so we tried it several time with no change, I tried a static check and lo and behold it was a couple of hundred rpm low.

Everything else was fine so we set 1000 and thought about what could be causing this problem. Looked around and saw some low cloud around just off the hills and thought, wonder if it could be Carb ice. Ran it up to 1700 and gave it a good dose of heat, not the Hot-drop-Return that we had done before.

Tried the idle and it worked fine.

So to get back on topic, if you have a power loss or can't develop full power don't forget your Carb Heat (where applicable) and leave it hot while you run the rest of your checks as it may take a while to work.

It really surprised me that there were no other indications of a problem apart from the idle response and then with further investigation, not meeting the static numbers. Also checking the Carb heat (for operation rather than to clear ice) didn't indicate a problem.

Never to old to learn!

[TLAW]

Hey blokes - just want to say thanks for such a useful thread - plenty of good stuff to read and think about in here!

:ok: :ok: :ok:

[Tinstaafl]

Csupilot, apart from some efficiency gains, the whole point of having two, independent & switchable ignition systems is so that a problem with one can be isolated & removed from the remaining system.

As an aside, I have to wonder what the designer(s) of the single drive/dual mag. system were thinking at the time, especially when the same engine platform in a differenct application could use separate mag. mounting pads.

[tinpis]

Dont forget the shoe horn in the navbag to prise the seat cover out of yer a$$