pfl procedures

[BigEndBob]

Whilst waiting for a flight at LHR, i flicked through the flying mags at the local library (WHSmith stand!) noticed an article on PFL,s.

A bit disappointed on the article, that the sequence of things to do in a PFL were published in a odd sequence.
O.K. i appreciate its not a pre flight brief, but many will read this article as revision of PFL's.
Perhaps it could have emphasised the correct sequence and put the various checks in the correct order.

For instance the first item should be as soon as the engine misses a beat that carb heat should be set hot.

[foxmoth]

Best PFL brief I have seen was Rod Jarvis from Goodwood - simple and it worked, I have it in one form but not as he did it or I would post it here. :)

[Dude~]

If the engine 'misses a beat' carb heat won't hurt, but if the engine suddenly stops completely would carb heat do anything at all?

The very first thing I was always taught to do is fly the plane - select best glide speed and go from there. No good re-starting the engine of you loose control of the a/c.

[hugh flung_dung]

I haven't seen the article but this is a good topic to discuss.
Engine fails, runs rough or otherwise indicates a lack of health at 2000-4000ft: adopt attitude for best glide, trim, carb heat on.
Remember to monitor speed throughout and (when practising ) warm engine every 500-1000ft.
turn into wind and pick field to one side (not straight ahead!)
elect landing area and IAP (Initial aiming point) 1/3 of way into landing area
track parallel to landing area at about half span separation while running the restart checks (assumes no fire or obvious mechanical disaster), reassess landing area
when IAP is just behind shoulder (about 1800ft agl) turn to track at right angles to landing direction and make Mayday call, reassess landing area
when IAP is just behind shoulder (about 1400ft agl) start a shallow turn towards downwind and assess sight line depression angle (SLA) to IAP, continue to make small changes of bank angle to maintain SLA while performing your standard pre-landing checks (delay undercarriage)
at the end of the downwind curve perform the forced landing checks
when on curved base and certain of making the IAP (about 600 agl) use flaps, sideslip or S turns to bring touch down point towards the near end.

At other estimated heights fly to where you should be in the above pattern.
When higher, fly to area of best fields.

Can this be controversial :p it's PPRUNE, of course it can :D

HFD

[BigEndBob]

Fly the aircraft should be instinctive. More important with a EFATO, where the speed would wash off quickly.
In reality though engine failure in cruise i would/have gone for throttle, mixture forward, carb hot , pump on fuel change tanks, etc. All of this would take about 2 seconds. There would be enough momentum in the aircraft to fly itself even if i did nothing and let go of the controls.

Why sit and wait 10 seconds whilst the a/c decelerates to best glide then another 30 seconds whilst wind and field is selected.

We have an engine getting colder or fuel lines empty.

I admit i don,t teach this.

Usually carb hot, fly a/c, trim, wind, field, key points, then restart.
Because it standardises for EFATO.

Also engine fire, i was taught if fire not out, then stop the prop. by slowing down toward stall speed to stop oil pumping out.
How many teach that.

[hugh flung_dung]

BEB: "Why sit and wait 10 seconds whilst the a/c decelerates to best glide then another 30 seconds whilst wind and field is selected." ... a slight lack of clarity on my part, I didn't mean to indicate that you sat and waited for the speed to come back - I'll change a comma to a full stop.

However, I do believe that the field selection should be the next step. Wind is found just by looking at the edge of the DI so there's no delay there. If you bumble along doing the restarts before finding a field the ideal field may drift out of sight. Nothing is lost by picking the field before attempting restart and something may be gained.

All the theory says that glide is much improved if the prop is stopped, but have you ever tried to stop a prop? - it's bl$$dy hard! I normally demo engine restart on an aeros course but it takes either a stall turn or a spin with mixture at ICO before the damn thing stops turning. The chances of stopping it during a forced landing (unless something is broken) is pretty slim.

HFD

[GusHoneybun]

It seems from the replies that there are two ways of doing things. First, is what we teach our students as part of Ex16. Second, is what we, as pilots, would do in the case of a dodgy engine.

What we teach the students has to be set as a standard. If they do get an engine failure we hope that the training they have will kick in. It will be a very stressful event to a low hour pilot (and a high hour one as well), but easily survivable. This is why we teach things in a set order and drum it into the student to, at all times, fly the aircraft.
The order I prefer is
1) fly the aircraft (best glide speed)
2) pick a field (shape, size, surface, slope, surrounding....)
3) restart checks
4) mayday
5) crash drills....

and I stress the only important items that must be completed are 1 and 2. i've seen too many pfl's go to ruin as the student stumbles through the mayday and promptly loses sight of the field.
The method that you describe HFD is preferable in my opinion to the square circuit method. This method will automatically compensate for the wind which takes another variable out of the equation. Good for students whose workload has just shot up 100%. However, I question the logic of turning into wind. Turning downwind will give you are greater groundspeed and hence present more fields as options. Once you reach the IAP or High Key, you turn as you described.


Second. We are talking about what we, as experienced pilots would do in the event of an engine failure. We have the capacity to swap the order of things a little bit. If we are chugging along at 90kts, we have a good 10 secs before glide speed and yes, we can knock a few levers or switchs in that time. Not had it personally, but know how easy it is to forget to change tanks. Especially on the PA28.......

Right, now my question. When I did the CPL, on the engine failure was told to put the prop to fully fine. At the time didn't think much about it, but surely that will increase the drag and hence increase the RoD? In a twin, engine failure = prop must be feathered. Anyone we has flown a twin near Vmca with an unfeathered prop will know why.....

[Oktas8]

FWIW, if I was going to do trouble checks following an engine failure, I'd put the propeller to maximum rpm (fine pitch). Once I had decided the donk wasn't going to restart, I would consider minimising drag by pulling the propeller lever fully aft (coarse or feather).

However, I suppose a particular manufacturer might say "in the event of engine failure, push propeller lever fully forwards" or similar, which might be why your CPL instructor did not explore the coarse propeller setting.

Alternatively, if a SE aircraft suffers a loss of oil pressure, it may not be possible to get the propeller out of fine pitch anyway due to the construction of the CSU.

HFD - is the SLA technique of RAF origin, or is it universally used in the UK?

[mad_jock]

Oktas8 its an excepted method. And taught by some not by others

The excepting bit by instructors can vary though if they are doing checks. You get some quite strong opinions on the pro's and cons depending on high or low wing etc.

Personally I used to teach both depending on what worked for the student. There are pro and con's for both. But to be honest as long as the student could get the plane to a point which they could get in. I really couldn't care which method they used.

MJ

[hugh flung_dung]

Oktas:
The SLA technique is normally called the "constant aspect method", it's been taught by the RAF for a long time and I believe was originally developed by Dickie Snell (but others here are more qualified to comment on that). A quick google will turn-up lots of hits.
Not all civvy clubs teach it but I think the popularity is spreading (rather like "point and power" on the approach - but let's not get the thread hijacked ;) ). It seems to be much more reliable than the other methods because there's visual feedback all through the process, wind is compensated and because the full procedure is event-driven.

GusHB:
Turning into wind first makes it easier to pick a field because you're looking for one that's aligned parallel to the aircraft. The pattern, up to the start of the constant aspect bit, gives you the chance to assess the field from a couple of directions before committing.
If you can't find a good field (and you have the height to be picky) then you need to try and fly to a better area. Turning downwind certainly allows you to cover more distance: you may achieve a G/S of 90kts rather than 50kts, so for every 1000ft you will cover 1.5 miles downwind or 1 mile into wind. Is it significant? - it depends:D
Personally, from normal cruise heights, I'd prefer bloggs to fly the approach to the best landing area that can be seen rather than hopefully look for somewhere better. People have landed on forests, factory roofs and roads - in my opinion this is better than running out of sky while trundling downwind in the hope of finding somewhere.

I'm slightly surprised by this debate over what to do with the prop on SEPLs. If the engine has stopped or is at less than about 15" you ain't got control of the prop! It will go to fine pitch regardless of where you put the lever. Maybe the reason for selecting fully fine was to protect the fine pitch stops during engine warms.

HFD

[mad_jock]

Whats wrong with forests?

Thats about all you have in some areas of scotland :D

Nice springy xmas tree plantation better than peat bog.

HFD what your views on the constant aspect in cessna types?

I have no fixed opinion on it. But i have heard some very strong words said on the subject to do with wings getting in the way of viewing the aiming point etc.

MJ

[GusHoneybun]

HFD

Nice try, but still not convinced.

Turning into wind first makes it easier to pick a field because you're looking for one that's aligned parallel to the aircraft.

also true if you are pointing downwind. Plus you will have a greater area to select from.

As long as you hit High Key, the procedure will work irrelevent of how you got to High Key. My point is that turning downwind will give you a greater selection of fields.
I know that this is a generalisation and turning downwind could take you out to sea or over forests or built up areas, but as a statistical model, it will yield more varity of fields.

[hugh flung_dung]

MJ:
Constant aspect works well in every type I've tried it in, high or low wing.

GusHB: turning downwind is OK if you're fairly high and have the time to be picky but if you do it at normal cruise heights you don't get to assess the field from a couple of directions before committing. I'd prefer a controlled arrival in the best patch available rather than turning downwind in the hope of finding something and running out of ideas while looking for something good.
On a test or checkout the thing that matters is that the person makes the best of the situation, has a plan and flies safely to a controlled arrival; the technique doesn't matter.

HFD

[BEagle]

I advise turning cross-wind whilst reducing to best glide speed. Because then you've got 3 options:

1. If very high, look upwind for a suitable highkey point;

2. If around 2000ft agl, look downwind for a lowkey point;

3. If very low, look to turn into wind and fly the final approach

Priorities are to fly the ac and survive. Titting about with endless checklists, stumbly MAYDAY calls and debating what to do with the wobbly prop lever are largely an utter waste of time - as are esoteric 'wotif' postulations.

Only when you're absolutely sure of making a suitable landing ground should you carry out the checks. Once you've done that, give a brief MAYDAY, telling them who, where and what's happening. Then squawk 7700 and turn the radio off to stop ATC pestering you when you're busy.

[BigEndBob]

Also where is it best to drop the gear.

Do we wait until we know we can make the field with due allowance for the extra drag, or drop the gear early to get a better feel for the glide performance with the gear out.

Thats if we use the gear at all.

Should it be lowered on every approach in case student forgets on a glide approach to the runway.

Stopping the prop i'm only advocating in the engine fire not out situation where an oil fire may torch through the cowl or smoke obscure the view ahead. Stopping the prop is quite easy for the usual Cessna Pipers.

Partial power failures probably present the ultimate challenge.
Do you commit all to a PFL or make the best of a raw deal.I always point out to students in EX6 part 2 flight at slow cruise how little power is required to keep us airborne.

[duir]

Seems as though the biggest cause of engine failure in light aircraft is fuel starvation. Perhaps it is prudent then to quickly check fuel on/switch tank, mixture rich 1st. When well rehearsed this takes around 3 seconds. Then trim for best glide. Of course this works best when engine fails in the cruise/decent and may not be such a good technique when climbing as the speed may bleed off rather more quickly. Putting the carb heat on may be useful, but it is highly unlikely that carb ice will cause the engine to stop suddenly without any warning signs before hand.

[Oktas8]

HFD & MJ - thanks very much for the constant aspect comments. The last 1000' of the PFL is usually not taught well in this country, and the SLA technique is not generally used, hence my interest.

Regarding whether to lower the gear at all on a PFL - undercarriage assemblies are among the strongest parts of the aircraft, and will absorb huge G and deceleration forces during the landing roll.

Accident reports that I've read seem to indicate that it's best to put the gear down and use it as a cushion between you and 'terra firma' (or 'sudden stoppa') in the event of a poorly judged landing.

The RAF in particular has some stories of aircraft driving the main gear through the wings of trainers on landing. Imagine the injuries if the gear wasn't there to absorb that impact!

Even in soft ground, if a modern aircraft lands near Vs0 with wings level, it is unlikely to somersault. That's not to say the nosewheel won't collapse of course! (In NZ we've had several ditching incidents involving PA28's and C172's where the aircraft remained upright during the ditching.)

Cheers,
O8

[Cricket23]

Hello,

I'm a student approaching the end of my course, but I'm not that happy with my PFL's.

Usually, my instructor has a field in mind when he pulls the throttle back and thinks I'm a bit mad when I suggested turning into wind first.

His view is that:

1) fly the aircraft (correct of course)
2) Chose the field (which could be in any direction relative to the wind)
3) Work out how you are going to get into it and therefore adjust whether you are downwind already, cross-wind or whatever.

Consequently, I'm finding that I don't have a nice framework within which to work and therefore the PFL's are a bit hit-and-miss (excuse the pun!).

He doesn't want me to turn into wind first as his opinion is that in real life your best options may not be in that direction and therefore you ought to able to cope with whatever circumstances throw at you.

Thoughts appreciated........

[hugh flung_dung]

Cricket23: your instructor is absolutely correct that you should be able to cope with whatever circumstances throw at you. The full CA procedure assumes that you have the height to do it, if not you need to fly to where you should be in the procedure for your height (and when higher, fly initially to area of best fields).
Remember, if the forced landing is successful it doesn't matter if you did any checks or told anyone, so concentrate on maintaining the aspect - if it's constant you're on the surface of an inverted cone and can only touch the ground in one place! However, it would be embarrassing to have to explain why the aircraft was in a field because you hadn't changed the fuel selector to the tank that still had some fuel in it!
Aligning yourself with the wind (use smoke or DI) makes field selection easier.

One thing to emphasise, however you do it always land into wind.. The kinetic energy (proportional to groundspeed squared) at touchdown needs to be dissipated somehow so it's pretty obvious that it needs to be as low as possible. Compare landing in a 10kt wind in an aircraft with a touchdown airspeed of 40kts. Into wind the energy at touchdown is 900M (M is mass of aircraft); downwind the touchdown energy is 2500M - nearly 3x the energy to be dissipated if you were to land downwind! In a 20kt wind the difference is 9 times!

HFD

[Oktas8]

Hi Cricket23,

Without repeating any of hfd's excellent comments, if you find your PFL's are a little hit and miss, try considering these points:


While trimming for best glide, and after the usual immediate actions like carb heat on, envisage a circle around the aircraft that represents maximum glide range in nil wind.
Adjust this circle for wind - move it downwind in other words.
Find a field within the circle, and turn towards it.
Plan aim point, low key, high key, blah blah - you know this!
Now plan how you are going to get to high key - cross over the field, or fly straight to it, or orbit (if very high), or forget high key and go straight to low key.
Of these, the last point is often forgotten, and leads to the rest of it being messed up. If you don't know how to do the last point, ask your instructor - it is critical, unless you are going to spend your life starting PFL's from abeam your field pointing into wind!

HTH,
O8

[Cricket23]

Thanks for the advice HFD and Oktas8. Weather permitting I'll give it another go on Sunday.