Jammed yoke

[andrew172]

Hi everyone!

I have a question: let's say you are flying a small GA plane, for example, a Cessna 172, you make a left turn and when you reach the bank angle you realize you can't get the stick back to neutral, the stick is jammed there and the aircraft keeps rolling. Is there anything to do in this situation? Can you overcome the roll with full opposite rudder? Is there any way to release the stick, if you apply as much force as you can?

I know that jet airliners and even turboprops are designed to overcome this emergency by separating the control columns applying high force on them or using handles in the cockpit to disconnect the roll, but what about small planes?

Also, the same problem in pitch, can you overcome it with trim and power? Does trim have any effect using it the opposite way acting as a mini elevator if the yoke is jammed? Or if the elevator itself is jammed?

Thank you very much!

[foxmoth]

? Can you overcome the roll with full opposite rudder? Is there any way to release the stick, if you apply as much force as you can? a lot of factors come in here, first of all controlling it will depend on how much aileron was in when it jammed - just a little will be fairly controllable, full probably totally uncontrollable. Releasing it will depend on why it has jammed and with what - it may be something like a spanner in the control run , in which case you would need to unjam it, if there was more than one of you in the aircraft then someone might be able to clamber down the back and free it or ot may come free with a little manoeuvring, if it is say a flimsy biro or something else fairly weak then yes you may be able to use brute force, but you might be surprised how much force is needed! one of those problems that depends on exactly what the problem is.
For elevator, yes, you can use trin and power. Both are worth having a practice, as is jammed throttle.

[Pilot DAR]

Good question Andrew. No, light aircraft certification standards do not require the redundancy or separation of primary flight controls as is required for airliners. Though rare in the extreme, a jammed hardover control in a light aircraft is probably unrecoverable. An example of the concern of this is the limitation placed on the operation of some Piper twins, where asymmetric flaps are a concern, and in the extreme not recoverable.

Some certification basis of light aircraft require a demonstration that the aircraft can be landed with a specified control disconnected, but not jammed in any given position. I have landed my C 150 without using the pitch control at all, using the technique specified in the flight manual, but it is not easy, and should be done with a safety pilot.

That said, if you have confirmed the proper operation of the flight controls prior to takeoff, and you're not doing negative G maneuvers, you're probably very safe from a jam. I have had wires behind the panel come loose, and snag controls, but yes, you can overpower those.

On the theme of control problems in flight, my worst was as follows. I have posted it here before, but I think it is worthy of consideration in this context:

So you’re going to do a maintenance test flight….

Part One - Which way is up?

A maintenance test flight was required, prior to the Transport Canada approved test flight for the evaluation of an external installation to the aircraft. I had flown this aircraft months earlier, for a very similar mod evaluation purpose, including spins and dives to 1.1 of Vne. Those flights were fine. It had not flown since, while it underwent inspection for a commercial C of A. This was the maintenance test flight following that inspection.

The aircraft is a Cessna U206F, with a Robertson STOL kit, and additional external equipment mounted. Following a review of the documents for the maintenance, a thorough preflight inspection, and normal start, I taxied out. Just before taking off, a final check of control freedom and direction, including the elevator trim tab – I have just read too many stories about flight control problems on test flights… Everything looked as it should from the pilot’s seat.

The aircraft was light weight at takeoff, and promptly leapt off the runway… Then immediately leapt more. A swift and large nose down control input seemed to help, but still it was heading for space! I confirmed that the pitch trim was set for takeoff (and it had been) then I rolled it all the way nose down. That helped a bit, but not really much.

By this point, landing back on the remaining runway was no longer an option. A circuit now lay ahead of me, which was going to be a muscle builder! I could lie on my back and hold my 30 pound daughter at arms length over me for a few minutes at a time. This flying was a lot more demanding than that! Flying with one hand so as retract flaps (very carefully) and adjust power, was manageable for only a few moments at a time. In downwind, I found that full flaps created the least uncomfortable configuration, probably simply because slower speed, less control force. I did not dare fly too slowly, being quite uncertain about how the aircraft would handle if stalled this way. During downwind, I was thinking about how I might jam my knee into the control wheel so as to relieve my tired arms – there really was no practical way..

Flaring for landing was an exercise in how to appropriately reduce the massive downforce I was applying to the controls. It worked. I taxied in, alternating thoughts of shock, and the old joke: I just flew in from – here! – and are my arms tired!” I also reminded myself how lucky I was there were no seats, occupants, or flight test ballast in the back for this first flight….

Knowing that I had had a serious pitch control problem, I asked for a check of the elevator and trim tab travels. The elevator was as it should be. The trim tab offered 3 degrees, where I would have expected to find five degrees according to the type certificate data sheet. I asked that the maximum travel in this direction be provided. I got 7 degrees. There was still a lack of certainty as to what the problem was, because I could not see how such a small travel limit error could produce such a dramatic effect. I invited the mechanic to join me in my next test flight. He reluctantly agreed, knowing that if he would not ride in it, why would I fly it. This time I was well prepared to abandon the takeoff, if things were not right. The takeoff was better, but the pitch control problem was still there. what had been a 40-50 pound push, was now 15-20. The mechanic now had no doubt that something had been very wrong on the first flight, as was still wrong now. I landed back.

After a rather puzzling review of the maintenance accomplished since my flight a few months earlier , the answer was found. The maintenance personnel had put a little too much thought into what they were doing…. The required maintenance had included the required overhaul of the trim actuator, thus it, and all the chain and cable, had been removed, and reinstalled. During the re-rigging, the technician had read the travel requirements for the tab in the maintenance manual. Instead of setting the tab for an up travel limit of 25 degrees, he set the travel to a “nose up” (tab down) limit of 25 degrees. This left the travel limit in the other direction of only 5 degrees, which I hereby attest is not anywhere close to the requirement!

By trying to “figure out” what the system required, the actual instruction was not followed as written. An unsafe condition was the result. The safety system further broke down, when the second signatory for the work accomplished did not detect the error. This was also a maintenance failing designed in by Cessna, as it was possible to mis-rig the system in the first place, and the manual did not give any warning to check for the mis-rigging.

Part Two – Is there enough?

With the trim error corrected, and many sets of eyes and minds making sure everything was just as it should be, I had the aircraft loaded so as to be at maximum gross weight, at the aft C of G limit. Off I went again. The elevator trim worked, well, though I was not completely sure of the indicator position. I was, though, satisfied that the aircraft was now conforming to its design.

I climbed the aircraft very high as I had done before, to do stalls and spins as required by the design approval test flight plan. The power off stall was very normal. While setting up for the maximum continuous power, full flap stall, things started to go wrong again…

With the power set, and the flaps selected to full, and passing 20 degrees deflection, I reached the forward control wheel travel stop. The nose was rising quite quickly now, with no ability to stop it, as the flaps continued to extend. The trim was set to full nose down, but that was really not a factor anymore. I had no more control! The only resolution I could think of was to retract the flaps as quickly as possible. Reducing power did not seem a good idea at such a nose high attitude. The stall warning was now screaming, and who knows what kind of stall recovery I would have if I could not lower the nose!

The flaps retracted back through 10 degrees just as the plane began to mush rather badly, settling downward quite nose high. I got it all sorted out, and resumed normal flight. Being up high, I decided to explore this situation, to try to fully understand it. Obviously another discussion with the maintenance crew would be in order, I’d better have something to tell them which was helpful…

I set up again for the power on stall, this time feeding in flap a little at a time. Sure enough, at 20 degrees flap the control wheel was at the forward stop again. I found that with lots of muscle, and the elevator trim set at full nose up (which caused a little more effectiveness of the elevator, because of the downward tab), I could get 30 degrees of flap down, and control aircraft pitch with slight flap setting changes. The strength required to fly this way prevented doing it for very long.

So I took the plane back to the mechanics, and reported that it still did not fly right. After a review of the loading for the flight, an error was found in the basic weight and balance. I had been 150 pounds too light! And 1 inch aft of the aft limit. Could this combination result in these poor flying characteristics? I thought not, but we reloaded, and I went again. Nope, it flew the same way. Back I went.

After a complete re-inspection of control travels, and the system, it was found that a previously undetected broken bearing in the elevator bellcrank was affecting the elevator travel. The cable tension made this not immediately apparent during a walk around control check. I would have thought, that such a defect would have been found during the recently completed commercial annual inspection. Oops!

It was also found that the horizontal stabilizer (which is not adjustable relative to the airframe) was more than one degree beyond its specified angle of incidence – but in the direction which would improve pushover control! There is no adjustment for the H stab on the tailboom. The bellcrank was removed, and the bearing replaced, with the expectation that the elevator travel would now be correct. It is noteworthy that this model year of the C206 specified a bushing, not a bearing, so it had been changed at some previous time, but no technical record entry could be found to describe this work.

I test flew again…

Part Three – Please sir, may I have more?

With the bellcrank reinstalled, and the elevator re-rigged, the problem was now worse! The elevator deflection with the maximum possible travel, and farthest stop setting, was even less than it had previously been. The broken bearing had been improving the elevator’s range of travel! I landed back.

All of the other elevator control system parts were checked and found to be correct applicability, and in good condition. There is no Cessna design provision to adjust out this problem. The only remaining possibility was a modification to the elevator control stops. It was possible to completely remove the Cessna installed elevator control stop block, leaving only the bolt as the stop. This did allow just enough elevator travel that the aircraft could be safely flown through all of the phases of flight. I tested very thoroughly, and found the aircraft to be acceptable.

It is sobering to realize that this aircraft had flown for years following the repair that had the horizontal stabilizer incorrectly installed, and the wrong parts put into the elevator system. In this configuration, had a pilot used full flap and high power at the same time, with an aft C of G, they would have run out of elevator effectivness instantly. Close to the ground, at could have been fatal. It is total luck that this never happened. In such a case, it is unlikely that the accident investigators could ever have determined that a bent airframe had not been correctly repaired years earlier. The cause might have been reported as “pilot failed to maintain control”, rather than the very different “pilot could not maintain control, due to airframe defect”. I also reminded myself that my month’s earlier test flight, which should have caught this defect, did not. I have to be more thorough, even though what I might find is not what I was up looking for.

I contacted a Transportation Safety Board friend of mine, to informally report that this had happened to me. After explaining the whole thing, he said “that happened to you too?”. Apparently this trim misrigging had also happed to Transport Canada’s own C 206, with the same scary, muscle building, yet accident free outcome.

It the subsequent times, I told everyone I met, who were associated with C 206’s about this, just as a word to the wise. Some time later, a fellow called me, and asked if I would come and fly his 206, it was doing the same thing ( though with less force), which he had remembered my describing. I went to the airport, and asked that the control and trim travel limits be measured in my presence. It was measured, and the trim was wrong (though not backward). I had the mechanics put it right, flew the plane, and all was fine!

[Dg800]

Jammed controls have been the root cause of many accidents involving GA planes and gliders. If you're lucky and the control is either jammed in (roughly) the neutral position or you can overpower what is causing the jamming rather quickly than you can either use the remaining controls (+power) to substitute for the jammed control (in the former case) or turn it into a non event that you walk away from although with a good scare (in the latter).
Any control that is permanently jammed with a significant deflection will get the plane in an unrecoverable attitude pretty quickly and then there won't be much that you can do if you don't have a parachute (either ballistic or personal).

Ciao,

Dg800

Edit to add: I'm of course referring to the primary controls only, as by the thread title I assume that is what you are referring to. Stuck flaps (in any position) or even a stuck throttle will lead to an emergency but usually not an unrecoverable one, i.e. you can manage to get the plane on the ground in one piece.

[Mechta]

On gliders, a part of the daily inspection is positive control checks in which all the flying surfaces and airbrakes are operated from the cockpit with someone holding the control surface to reist the movement. The regular assembly/disassembly of gliders that live in trailers must be part of the reason for this, but I wonder how common it is in power flying?

Having flown an R/C model on which I had disconnected the elevator clevis to make an adjustment; then having been distracted, flew the model with the clevis disconnected but pushing on the control horn, I know how easy it is for a visual-only control check to lead one to believe all is ok. Fortunately in the case of the model, pushing on the control horn gave up elevator and it stayed in alignment for the whole flight, so I was able to complete the undulating circuit and land without damage.

There are at least two cases in which pilots have parachuted from their gliders at the top of the winch lauch having discovered their elevators were not properly connected. One glider had had its daily inspection, then had its tailplane removed and refitted by a third party without a note in the logbook or mention to the pilot who was going to fly it.

[1800ed]

I had an alarming insight into how the Piper Autocontrol III autopilot works on a recent flight converting over to an Arrow. While approaching base I needed to make a slight descending right turn to point in the right direction for down wind, forgetting the autopilot was engaged - I instantly thought the yoke was jammed!

Asking my instructor if it was normal for the controls to feel so heavy, he simply replied "yes, when the autopilot is turned on". The manual says it can be over powered if needed but I'm slightly skeptical over that one!

[andrew172]

My concern is for normal roll rate, as we do in pattern turns for example. It's really scary to know that even for normal turns, for which the usual entry is using small ailerons deflection, you can do nothing with the opposite rudder if the yoke jams, but I hope that as you said here, in situation like that you can keep it fairly controllable. It's pretty clear that at full deflection or I guess even at half it's unrecoverable but that's for aerobatics, isn't it? And what about a personal parachute? It would be possible to escape from the aircraft if it's flying an uncontrollable roll?

I read somewhere that with a jammed yoke or elevator it is impossible to fly with the trim wheel because it has no effect being too small to act as an elevator. Can it be possible?

Sorry for being pushing, I don't want to be exaggerated, I'm a PPL student and I just want to be prepared for the unexpected.. In my opinion, it's ok thinking about all kind of possible failures while on ground and be ready to face them in the air, and doing that, I realised that this 2 problems regarding ailerons jammed deflected or elevator jammed seem to be unrecoverable in some circumstances, that's why I'm asking about them. I didn't find others come that close to a certain out of control situation, maybe you know more dark scenarios :ooh:

Thank you!

[JW411]

andrew 172:

"I know that jet airliners and even turboprops are designed to overcome this emergency by separating the control columns....."

Not true! The DC-10 had no such facility for all controls were hydraulic. The Bae 146 had a disconnect handle for the elevators and the ailerons (the rudder was hydraulic) but that was only because BAe designed those controls to be operated by old-fashioned bowden cables running to servo tabs.

Which other jet airliners do you know of that have this facility?

[andrew172]

I read it from the 737 manual and it states that in case of control jamming you can separate the yokes by applying some force. Also, I heard that 767 (and the 777, I guess) has a split elevator system which in case of emergency can be used as a half from a yoke or the other. I didn't read a lot of details about these features because it was enough to know they are present to help the pilot in an emergency. My concern was for small single engine aircraft where you don't have that redundancy and you actually can't really deal with the problem.

[foxmoth]

I read somewhere that with a jammed yoke or elevator it is impossible to fly with the trim wheel because it has no effect being too small to act as an elevator. Can it be possible? not so, though if it has not jammed in the neutral position that does make it much harder and you would probably need to adjust power to get the nose in a sensible attitude. Not sure how far along your PPL you are, but worth trying it with your instructor holding the cc when you are in the later stage of the course, you will find the way to do things is SLOWLY with very small trim and power changes.
Chute is the best option if you have one and is recommended for aeros.

[peterh337]

You can definitely control pitch pretty well by using the trim wheel, with a solidly jammed elevator, but the trim wheel then works in the opposite direction to normal.

I've tested it - it works on the TB20.

[Maoraigh1]

Surely that wouldn't work if the elevator was jammed up or down much? I would think it would only work if the elevator was jammed almost neutral.
(I've flown a Jode DR1050l on rudder-elevator trim-throttle, with the stick free.)

[sevenstrokeroll]

first off there seems to be some confusion about airliners and controls...I've flown the BAE146, B737, and the DC9 (the best of the lot).

all have some sort of break away on the control yokes or similiar device...that is if ONE part of the control yoke system doesn't function, you move the OTHER yoke hard enough and a clutch between the two yokes disengages and allows one yoke to move...but it only moves a portion of the flight controls...and whether or not they are hydraulically powered doesn't matter at this point in the control system.

having said that:

I flew a piper arrow some 30 years ago and the bicycle chain/sprocket system of aileron/yoke etc came loose..the actual chain jumped the sprocket ( I did find this out after landing).

so I made a long straight in to an airport NOT surounded by thousands of houses, using rudder and we made it.



the way to find out is go up, put the plane into a normal bank...don't move the yoke and press the rudder pedal...of course if you are too slow you might end up on your back in a spin or something, so don't get too slow...use plenty of altitude...I demonstrated stuff like this with my students...indeed I made them learn how to slop through a turn with wings level, just with rudder or in the case of a twin, with assymetric thrust.

maybe you hven't had good instruction so far...find a really old time instructor or designated examiner and get a lesson from him

chances are you don't ram the controls over hard to enter a normal turn, and the idea of all flyings is...if you do something and it don't feel right...stop it! get back to a normal situation.


and yes, if a plane is right out of MX...don't trust anything!!!!!!


----

ANDREW, your questions should be addressed by your instructor and if not by him, certainly the chief instructor ofyour school. I will relate this to you...during th early days of flying a CAA inspector (forerunner of the USA FAA) took off in a plane in which the ailerons had been hooked up backwards...he landed using just the rudder for roll/yaw...at that time it was required that the rudder be able to over come the aileron for just such an eventuality...

of course in the 737 there was a rudder hardover that could not be overcome by the crew causing a crash...additional training and procedure helped us overcome this problem.

so:


always check the flight controls prior to takeoff...and LOOK outside the plane and make sure they move in the correct way and return to neutral

rarely in any plane do you need full YOKE/CONTROL throw in normal flight...perhaps for crosswind landings is one possible exception, so you will probaably be able to handle the problems you describe

and if your instructor is very new, maybe he doe3sn't know the answers...find another instructor...and not one who just wants to take you up to scare you

you should not get scared into learning things.

[foxmoth]

maybe you hven't had good instruction so far...find a really old time instructor or designated examiner and get a lesson from him Andrew has not said how much he has done so don't be quite so quick to jump on the instructor, I would cover this, but certainly not untill all the basics are out of the way and probably not until fairly near the end of the PPL, most students find this a bit much until then.

[sevenstrokeroll]

foxmoth...if my student asked me an intelligent set of questions as andrew has, I would answer that set of questions at the earliest opportunity...if he has to worry about such things he will not get the full benefit of the basics.

ask the questions, get the answers

and I would certainly take the time to discuss what to do with control problems, throttle failure and the like PRIOR to first solo.

[sevenstrokeroll]

oh, by the way

if you have hydraulic operated controls, that DOES NOT MEAN you couldn't have YOKE malfunction and the cables, pulleys et all could still manipulate the hydraulic portion of the controls...and the instinctive yoke breakaway could hep you alot (instinctive means, in this cas3e...hey the yoke is jammed...I better put every ounce of force my arms can muster and BAM, ok my control yoke has unjammed and a PORTION of the flight controls can be controlled by me...and a safe landing just might be possible)

[peterh337]

Surely that wouldn't work if the elevator was jammed up or down much? I would think it would only work if the elevator was jammed almost neutral.I am sure you are right, because the trim tab is very small.

I think the biggest danger is somebody leaving some object in the airframe, which jams the controls. This has happened; from vague memory a number of times. Control linkages coming off completely (without jamming the controls) are not uncommon too, but they should not cause a crash.

Concorde had an interesting system, whereby strain gauges were placed on the yoke(s) which drove a separate control system so that a totally (locally) jammed yoke would still work - again from vague memory.

[foxmoth]

foxmoth...if my student asked me an intelligent set of questions as andrew has, I would answer that set of questions at the earliest opportunity...if he has to worry about such things he will not get the full benefit of the basics.

And how often do people ask questions on here that they have not asked their instructor? Yes that is what SHOULD happen, but they might not be going to the field for some time and the 'net is very convenient.

[sevenstrokeroll]

foxmoth

when I was instructing some 30 years ago, I didn't have e mail...but I would certainly give my student my e mail address now and he could write me for an answer.

but back in prehistoric times, I would certainly have encouraged my students to TELEPHONE me with a question.

Now grant you, I would not give an hour lecture on the phone, but it would open the dialogue about such matters.

andrew, do you have your instructor's phone number?

andrew, how often do you take a lesson?

If you are learning to fly and flying less than one time a week, you might want to re evaluate your learning scheme.

[Big Pistons Forever]

Sorry for being pushing, I don't want to be exaggerated, I'm a PPL student and I just want to be prepared for the unexpected.. In my opinion, it's ok thinking about all kind of possible failures while on ground and be ready to face them in the air, and doing that, I realised that this 2 problems regarding ailerons jammed deflected or elevator jammed seem to be unrecoverable in some circumstances, that's why I'm asking about them. I didn't find others come that close to a certain out of control situation, maybe you know more dark scenarios :ooh:

Thank you!

Flying is all about managing risk. The most important part about risk managing is understanding the concept of probability and consequence. That is how likely is any particular scenario and if it where to happen how severe would the consequences be ? Obviously as an instructor I will place a very high level of effort preparing you for the high probability, high consequence scenarios.

So for example getting too low and too slow on final approach will probably happen to you and the consequence of letting the aircraft stall and maybe spin will be very severe. Similarly not checking your fuel quantity before takeoff will, if done on a regular basis, lead to a high probability you will run out of gas which again obviously has going to be lead to a high level of severity in the outcome. So I will put a lot of emphasis on you managing your pitch attitude and power so that you fly a safe final approach profile and my preflight inspection training will emphasize the importance of checking the fuel. These actions are an example of you being trained to mitigate and manage dangers.

The hard part of risk management is how one deals with low probability but high consequence scenarios. A jammed control is a good example of one of those. It is a very low probability event especially for simple flying club powered aircraft (it is more of a concern for gliders however) and virtually all pilots will fly their whole career without ever having to deal with this emergency. There are many many emergencies which are much more likely for you to experience.

There are is a practical limit to how much you can specifically prepare for and the danger is to so worry about the extremely rare events you neglect to place a sufficient effort in learning to manage the more common emergencies.

However the chance of a jammed control is not zero and obviously it is a very serious emergency should it happen so If you were my student and asked this question here is what I would say.

A jammed control is an extremely rare occurrence and therefore it is important that before you worry about this kind of event you learn and understand how to deal with the much more common emergencies which I will be covering during the PPL course.

Your question is not a silly one however and we are already indirectly mitigating this risk in other ways.

The first is understanding what we are looking for in the preflight inspection so we are more likely to identify a problem which could lead to a control jam before we even takeoff. Remember last month when I pointed out the aircraft we were about to fly had just come out of a 100 hour inspection? You recall we spent extra time looking for tools left behind, loose carpet that could foul the controls, missing panels etc etc. This is an example of managing the increased risk that will inevitably exist when substantial work is done and heps mitigates not only the risk of jammed controls, but other things that could present an inflight problem

The second way we mitigate this risk is by having a complete understanding of the effects of the aircraft controls and so in the event of a jammed control we would use this knowledge to maximize the chance of retaining enough control to still fly the aircraft, so for instance, using roll yaw coupling to roll an aircraft with jammed ailerons. So while we are not going to specifically cover the jammed control scenario you will nevertheless have the kinds of skills which can be used to deal with this emergencies and other low probability events by the end of the PPL.

Oh and while we are talking emergencies tell me what you are going to do if we are cruising out to the practice area on our next flight and the engine suddenly starts to run rough........

[Pilot DAR]

Andrew, the relevant certification standards in the FAA are as follows:

For FAR Part 23:

Sec. 23.671

General.

(a) Each control must operate easily, smoothly, and positively enough to allow proper performance of its functions.
(b) Controls must be arranged and identified to provide for convenience in operation and to prevent the possibility of confusion and subsequent inadvertent operation.

For FAR Part 25:

Sec. 25.671

General.

(a) Each control and control system must operate with the ease, smoothness, and positiveness appropriate to its function.
(b) Each element of each flight control system must be designed, or distinctively and permanently marked, to minimize the probability of incorrect assembly that could result in the malfunctioning of the system.
[ (c) The airplane must be shown by analysis, tests, or both, to be capable of continued safe flight and landing after any of the following failures or jamming in the flight control system and surfaces (including trim, lift, drag, and feel systems), within the normal flight envelope, without requiring exceptional piloting skill or strength. Probable malfunctions must have only minor effects on control system operation and must be capable of being readily counteracted by the pilot.
(1) Any single failure, excluding jamming (for example, disconnection or failure of mechanical elements, or structural failure of hydraulic components, such as actuators, control spool housing, and valves).
(2) Any combination of failures not shown to be extremely improbable, excluding jamming (for example, dual electrical or hydraulic system failures, or any single failure in combination with any probable hydraulic or electrical failure).
(3) Any jam in a control position normally encountered during takeoff, climb, cruise, normal turns, descent, and landing unless the jam is shown to be extremely improbable, or can be alleviated. A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable.
(d) The airplane must be designed so that it is controllable if all engines fail. Compliance with this requirement may be shown by analysis where that method has been shown to be reliable.]

You can see the differences, and more rigor of the Part 25, which is for large aircraft.

For my limited experience with large aircraft, there is either a pin that either pilot can pull, to allow the two pilot's control wheels to operate independently (DC-8, if I recall from 30 years ago), or something purposefully breaks in the control run with high pilot force (B707), or there is a calibrated release joint like a spring loaded cam (Dash 8).

Light aircraft generally will not tolerate the weight or cost of such systems. The risk is just not perceived as being great enough to warrant such complexity for these aircraft.

Think of it a different way: The certifiers know that us little plane pilots are much more likely to make the many stupid mistakes which Big Pistons points out, so a control jam is a long way away from being a "top of the list" risk for little planes. The risk does not warrant the cost and weight for the system to protect. The bigger planes, being flown by two competent pilots, reduce the likelihood of those basic stupid mistakes, so the other risks come more to the forefront. Plus, there are now the two pilots, so twice the chance that someone can fly at least half the plane, if the jammed half can be released. It's now worth requiring the system, in an aircraft where the weight and cost can be carried.

In a Dash 8 aileron system, the gizmo looks like this. it turns the cable motion into a pushrod motion, with the cam release in between the two. Can you imagine the cost of this assembly in a Cessna?

Sorry, Photobucket refuses to resize the photo to 640 by 480, even when I take it in "small".

http://i381.photobucket.com/albums/oo252/PilotDAR/IMG_8047.jpg

[sevenstrokeroll]

since 1975 I've had an aileron control problem, a trim cable that physically broke (twangggg) on a cherokee six, and a moisture/freezeup on a seneca for the stabilator.

I'm still here andrew!

[Big Pistons Forever]

I have been flying since 1976 and have never had a primary flight control fail or jam. I had one significant emotional event when the elevator trim on a T 28 Trojan was connected backwards.

However I blame myself as the flight was the first test flight after the aircraft was completely reassembled after a a major rebuild. I checked for full movement of all controls and correct movement of the ailerons, elevator and rudder but did not check that the trims were moving in the right direction just that they went to full travel :O

The resulting test flight was more exciting than it had to be but in the end I had an opportunity to find the fault on the ground but did not. I am willing to bet that many of the examples of jammed controls presented a similar opportunity....

[peterh337]

That's a nice bit of CNC machining, Pilot-DAR :) Not as pricey as one might imagine, though probably is by the time the paperwors is generated...

a moisture/freezeup on a seneca for the stabilator.

I've had that too, and know of several instances of people I know. It seems to be either incorrect lube (my case) or some level of water ingress, all the way to the tail section of a PA46 filling up with a massive amount of water during a downpour followed rapidly by a climb to high altitude.

[Pace]

Peter

I had that very thing in a Seneca Five twin awaiting clearance to Join CAS at FL120.
i was down at 3000 feet in very heavy intense rain got the clearance and started the climb trimming the aircraft for that climb.
Approaching FL120 I went to level and found large out of trim forces with a jammed trim wheel.
I soon worked out what had happened and there was no alternative but to come down to below the freezing level.
A quick chat with the controller and very uncomfortable out of trim forces in the descent soon had the problem solved.
I then climbed again this time with no problems and continued on my merry way.
The Grease packing in the Linkage is important and it has to be the right type.

Pace

[andrew172]

In have about 10 hours in my PPL logbook, but I have more hours in small planes, I flew with a lot of friends, some of them are private pilots or even commercial pilots and they told me they have no idea of jammed controls, they don't know any local crashes because of that problem, the same answer from my instructor, that's why I asked here on this forum where a lot of experienced pilots write and maybe some of you heard about these things.

As I said, I use to think about possible scenarios and what should I do in those cases and I found that some of them are not covered in the PPL training or in manuals and it seems that instructors have no intention to tell us about them (if we don't ask) during training... maybe these problems are too rare and usually deadly to talk about them or even instructors know nothing about them from their training.

Also, as some of you said, there are risks we can manage, for example an engine failure is not usually an out of control situation, we are trained to glide, to choose the best spot, to avoid populated ares etc. but after we are trained for these problems, I'm thinking, are there any out of controls sitations? And then I find that a deflected jammed control is one of them and it seems to be unique, because excepting a structural failure (I really don't worry about it, I think it's almost impossible for a well-maintained and inspected plane to lose a wing in normal 1G flight as long as it can handle about 4-5G or to disintegrate if there is no bomb on board or stuff like that, for me, that's really the last cause to crash), I didn't find any possible failures which can lead to an out of control situation, maybe a heavy spread fire, but we know to land as soon as possible if we have signs of fire, even strange smell. If you know other scenarios, I'm really curious to know them http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/evil.gif

I know there are hundreds of causes for a crash but all of them seem to be manageable excepting what I said above, even if the manageable ones happen more often, the fact that you can do your best to avoid them and if it happens it's not an out of control situation makes you feel pretty confident and you know that whatever happens you are in control. That's why for me it's not ok that you have nothing to do if your yoke jams deflected... maybe using just small roll rates in turns is the solution, is it? Just kiddinghttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/embarass.gif

Anyway, don't think I would give up because of this or I'll fly worried about it, I'm already too addicted, so there's no way to stop me being in the airhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

About aerobatics and parachutes, someone said that it's hard to escape from a rolling plane because you can't open the doors, what about canopies? It seems that there are a lot of aerobatic planes which have canopies, not doors.

[cats_five]

On gliders, a part of the daily inspection is positive control checks in which all the flying surfaces and airbrakes are operated from the cockpit with someone holding the control surface to reist the movement. The regular assembly/disassembly of gliders that live in trailers must be part of the reason for this, but I wonder how common it is in power flying?
<snip>

A positive control check won't protect against something rattling around in the glider jamming the controls. It should find if you have mis-rigged the glider.

There was a glider lost earlier this year (pilot OK) because the pilot stopped part-way through rigging for rain and forgot to connect the elevator. He can't have done positives afterwards and launched with the glider in that state. Luckily he was able to bail out and parachute to safety. Most gliders are made to be relatively easy to bail out of - canopies are large for visibility and designed to be easy to eject.

All club gliders should get a positive control check as part of the normal DI, some those of us keeping our private gliders rigged in a hanger only do the check after the glider is rigged.

[sevenstrokeroll]

andrew...your questions are valid, your flight instructor should be able to answer them, and if he can't...ask him to look it up and get back to you.

there are all sorts of ways to fly a plane using a different combination of controls. There is a story, true, of a Delta Airlines Lockheed 1011 Tristar that took off out of San Diego, USA...its stabilator jammed...the pilots figured it out and used assymetric thrust, flaps, and other ideas to keep the plane under control (they couldn't get the NOSE to come down in the normal way)...they managed a safe landing at KLAX.

IF you make a normal turn in the C172 and the ailerons jammed, you would have a decent chance of stopping the turn with the rudder. But you would have to watch your airspeed as there will be much more drag slowing you down.


I encourage you to read many books about the subjecte of flying...including the following"

The Spirit of St. Louis
Fate is the Hunter
Stick and Rudder

and see if you can't find a better instructor

[foxmoth]

About aerobatics and parachutes, someone said that it's hard to escape from a rolling plane because you can't open the doors, what about canopies? It seems that there are a lot of aerobatic planes which have canopies, not doors.

Most aero aircraft either have jettison able doors or a canopy that can be opened or got rid off, if not aero then you are unlikely to have a chute!

Sevenstroke seems determined that you change your instructor, it MAY be something to think about, but this question should not be the sole reason, you could end up changing from one you get on with to one that pushes too much or causes you other problems, only you know what your instructor is like, though I do agree that questions like this should be answered by him.

[peterh337]

The Grease packing in the Linkage is important and it has to be the right type.There is a tendency in GA maintenance to use certain well known aerosol lubricants... when you query it, the reply is "we have been doing this for 20 years and never had a complaint". Hardly suprising, looking at the typical mission profile there.

[stevef]

Interesting comment about aerosols. Try lubricating piano hinges with a traditional Fluid 3 can... You're wasting your time, really; the oil rarely penetrates, especially on re-painted control surfaces. Piper have the right idea by using nylon-lined self-lubricating piano hinge segments on some aircraft.
Speaking of control restrictions, I remember the rush to supply an overhauled Vickers Merchantman (Vanguard, more or less) nose gear upper housing that had cracked after a 'firm' landing due to the elevators locking up in the cruise after improper de-icing and the water freezing in the curtain gap. I think it would have been in the mid-80s and the aircraft was loaded with 14 or so tons of newspapers.
Maybe someone here has more knowledge of the incident. It was an Air Bridge Carriers aircraft and I think the destination airfield was Luton.

[despegue]

C172 can very easily be flown using the doors and throttle. It was a required exercise toland it when i got my initial training.

[Pilot DAR]

As stated, I think that Andrew's original question was fair, and appropriately cast to the internet aviation world for comment. Andrew is not asking for specific guidance or detail which would subvert the training efforts of his instructor, he's asking a question which is well agreed to be out of the norm.

As it is out of the norm, how could Andrew expect that his instructor would have answers as detailed, and broad as those he has received thus far on this forum? Maybe Andrew's instructor is super knowledgeable, but every bit as likely, that instructor is learning along with the rest of us. Instructors are certainly not the ultimate end source for information, particularly when it is beyond the scope of the required training.

stevenstokeroll's suggestion that Andrew look for a better instructor, simply based upon this learning effort on Andrew's part, is, in my opinion, silly! It seems to me that with 1270 views, and only 32 replies, to this thread, that a lot more people have a question about this, than an answer to offer! To expect an instructor to have all of these answers is unreasonable, and to suggest a change because they might not is even more so. There are few instructors who also have a detailed maintenance or certification background, so expecting them to know these design rationale is expecting way too much! Yeah, if they go to "look it up" that's good. They will probably end up asking on PPRuNe! The kind of aviation professionals who most likely have this experience, and these answers, cost a lot more by the hour than your average instructor, and there's a reason for that!

Andrew, ask away, that's what the forum is for, and don't start looking for a new instructor because of what a few nay sayers say here. 10,000 hour grey haired instructors are great if you can find them. But sometimes, you have to work with who you get. As an instructor, they may be new, but they demonstrated the required skills in pilot training, and understanding the deep down details of control systems are beyond those skills!

IF you make a normal turn in the C172 and the ailerons jammed, you would have a decent chance of stopping the turn with the rudder. But you would have to watch your airspeed as there will be much more drag slowing you down.

Well, yes. But if you ever had the 172 ailerons jammed, and the rudder keeping you straight, you'd have a heck of a time landing the aircraft, and that is an important final element of the flight!

Yes, they can be flown with the doors, but it would require a considerable amount of practice to get to the point where a landing would work out well. Despegue, have you tried this? Which way will a Cessna 1XX turn if you open the left door part way during cruise flight?

Aside from the aforementioned terrifying experience in the C206, I have had C 180 flaps jammed at 20 degrees (later found to be a track broken right off), a completely misrigged C 150 rudder, which became useless once airborne, a bent C 182 aileron pushrod, which dramatically changed the way he 182 flew, a runaway stabilizer on a C 185, elevators in a C 150 which were partly jammed, so as to prevent a normal flare to land, flaps which could not be retracted in a C 150, C 172, and C 177, and a spoiler which could not be retracted simultaneous with flaps which would not extend in a Mooney.

I'm not trying to say that all flight control problems can be managed, but many can. But then I do a lot of maintenance test flying - the most dangerous type of flying, I think. Today, one of the Thielert engines I was flying was very grumpy. The other one was fine though - I only really needed one of them to run well!

Inquire, but don't worry about this Andrew, you'll be fine...

[peterh337]

Interesting comment about aerosols. Try lubricating piano hinges with a traditional Fluid 3 can... You're wasting your time, really; the oil rarely penetrates, especially on re-painted control surfaces.

ISTM that new aircraft tend to be sprayed with the primer, then assembled, then the whole lot is sprayed with the base and then the lacquer.

The result looks "nice" (no chewed-up paint in screw heads, etc) but there is going to be hardly any lube inside the moving parts because it would interfere with the paint ;)

There is also a much wider issue with using aerosol (or other liquid) lube when grease (of the correct temperature range) should be used. Grease will easily make it from one Annual to the next, but the liquids are gone long before. It is always "the next owner" who faces the music... or maybe the present owner who treated his plane like his BMW and just dumped it at the dealer for each service.

Most maintenance companies do Annuals (and the 50hr checks too, if they do them) at a fixed price; say £2500 and £500 respectively. Obviously it is in their interest to do the minimum "standard" work and this definitely won't include dismantling, cleaning, and greasing e.g. control surface linkages. They just usually spray-lube them, leaving all the accumulated grime in there which makes for a nice grinding paste :) I have never come across a maintenance company which does this right. If you use grease then the non-exposed linkage bearings need doing maybe only every 2 years. I pay extra to have this done.

Piper have the right idea by using nylon-lined self-lubricating piano hinge segments on some aircraft.

... and then the maintainance company sticks some lube in there which attracts the grime and quickly the hinges are trashed :ugh:

Socata used PTFE sleeves hinge pins, which are a nice idea but don't work. They need to be kept very clean; any grime (which will get picked up) just mucks them up. There are 4 pins which are £100 each, and the 4 hinges come to ~ £1000 for the set. The problem is that the diameter accuracy on the sleeves is necessarily crap (+/-0.3mm or so) so there is a lot of slop in there, even after you have just spent all the money having it all replaced (£1500+), and the slop creates rapid wear... there is a regime which kind of works, which involves replacing just the end 2 pins (£200) a few times over say 10 years, and replace all the rest every 10 years.

You can't beat stainless pins in bronze bushes (http://en.wikipedia.org/wiki/Isambard_Kingdom_Brunel) :) Even the thermal expansion coefficient is closely matched, which is relevant on high altitude flights.

[stevef]

Peterh337 - it sounds as if you've been very unlucky with your maintenance choices! I've been an aircraft engineer for well over 30 years and never worked for an organisation that didn't clean bearings and lubrication points on a servicing check of any level. If they were called up on the approved factory or maintenance schedule, they were complied with.
Almost all external and internal bearings are sealed nowadays (excluding the likes of the antiquated BN Islander flap, rudder and trim jack ball ends) and I don't really see the advantage in covering them with grease, especially considering that Aeroshell 7 is quite hygroscopic. Likewise with light aircraft wheels - I've seen literally hundreds corroded in the bearing boss circlip area because the felt seals are treated with grease, which absorbs moisture (and there's obviously plenty of that due to landing and taxying in wet conditions). A very light soaking in Fluid 3 general purpose oil puts a stop to that.
Re non-exposed linkage bearings, I'b be very surprised to see the grease lasting more than a hundred hours on the actual contact areas, never mind two years. More cosmetic than anything else in my opinion. It would be interesting to see other viewpoints, such as from A&C.
Anyway, apologies to the originator for going off track.

[Big Pistons Forever]

In have about 10 hours in my PPL logbook.

Andrew I noticed that you posted the same question on Avcanada. The replies were considerably less polite than those here, but the theme from that thread is IMO absolutely correct. As a 10 hour PPL what to do in the event of a jammed control is the wrong thing to be worrying about. The beginning of the PPL is where you learn the foundation skills and knowledge which you will use for every part of your future flying. Without first learning those you will not understand the the concepts and have the skills to actually deal with jammed controls.

In 24 + years of flying instruction I have never met a 10 hour PPL who could describe the workings of every system in the aircraft and tell me what the correct actions required for a failure of those systems and why the actions in the POH emergency procedures are carried out. That is what you should be studying with respect to emergencies, not obsessing about extremely rare failures.

Bottom line: Your instructor is, correctly, not answering your questions because they are not relevant to what you need to be learning at this stage of your training.

If you still feel this subject is vital to you I suggest you pm Memphis_Bell, I am sure the 2 of you will get along just fine :rolleyes:

[Pilot DAR]

I certainly respect Big Piston's formal instructing experience, which is vastly more than my none! I will tread very lightly in appearing to challenge him, because I rarely disagree with him.

I agree that a 10 hour PPL should not be obsessing about very rare failures, and should have their mind on what is being taught. Detracting from a lesson by going off on a protracted tangent, well beyond the instructor's reply, is not what you should do during training. Follow the lesson as taught, and keep your mind on the job. Big Pistons is right, you do not need to know what to do about a control jam, at this stage in your flying.

However, if in your desire to become a pilot with deeper knowledge, you ask questions of your instructor, which do not detract from training, I think that you are entitled to a reasonable answer. This particular subject is deep, in that it is rare, (which is what most of us told you first), but when it happens, it can be really bad.

Your instructor knows for certain, that as long as you fly the planes you are assigned, preflight as taught (and don't fly if you detect or suspect a defect), and don't zero G them, you are not going to have a control jam. How do I know that your instructor knows this? I just do, 36 years of flying tells you some things....

If you're obsessing about control jams - stop it. If you're genuinely interested in the design of systems in aircraft and what is required and what is not, and why, because you would like to deepen your knowledge about aircraft, and in doing so, you are not detracting from your training (frustrating your instructor), I can (and have) support that. It's what you do with what you know.

If you are asking your instructor lots of questions outside the scope of your training pay for the extra training time. It's only fair....

You have asked questions here which could be beyond the knowledge/experience depth of some new instructors. Doing that is not a crime, as long as you remember that no pilot likes to have their authority, skill, or capability challenged by a 10 PPL student! Tread lightly, and be diplomatic. Perhaps you have asked the right question the wrong way here, and on AvCanada. Maybe you meant to ask: "has anyone had any experience with jammed controls, and what did they learn from that experience to make them a more safe pilot?". I don't mean to put words in your mouth, but with that wording, everyone can keep their pride!

I will disagree with Big Pistons on one thing though.... Don't PM Memphis Belle, we'd just have two bitter PPRuNers then!

[abgd]

Nothing here suggests to me that Andrew172 is anything near the same league as Memphis_Bell...

Whether or not it's a question of practical significance, I've enjoyed the replies here and whilst I agree it's not something that should keep a pilot awake at night, it seems a reasonable question for a newbie to wonder about - especially if transports have safeguards against such failures. My own mechanical experience comes mostly from bicycle maintainence and it's a source of unending delight to me, the extent to which aircraft primary controls are more reliable than even the best maintained bicycle brake cables and rear derailleurs.

[foxmoth]

I would go along with Big Pistons and DAR, strange how Sevenstroke has gone quiet now!:ok:

[Big Pistons Forever]

One thing I really like about pprune (and avcanada) is stuff comes up that forces you to examine what and how you think about things.

I have to say that the issue of jammed controls is one of them. I am still hard over about futility of 10 hour PPL's obsessing about this and Pilot DAR's advice to just "stop it" is right on IMO.

However it has forced me to ask the larger question of whether or not there is a place for this discussion at any stage of flight training. At the PPL level, I think not, but at the CPL and flight instructor rating maybe so.

First I think a distinction needs to be made between jammed controls and disconnected controls. A disconnected primary flight control is "better" then a jammed control as it will fair it self to a aerodynamically neutral position. If the control has a movable trim tab then it can be indirectly moved with the tab thus allowing some control over that surface. A jammed control is much more serious particularly if it jams with considerable deflection. In this case secondary effects have to be used and there is a significant possibility it will be impossible to retain control of the aircraft, in which case you are well and truly screwed.

I do not directly talk about the subject of disconnected or jammed controls when I teach the CPL or FI courses but I think I am going to change that and incorporate some discussion of these failures in my instruction.

I am planning on presenting 3 main themes.

The first is that if you successfully survived a jammed control event but it turned out the cause of the jam was something that was could reasonably be discovered during the preflight inspection then you should not be congratulating yourself on your superior flying skills you should be profoundly embarrassing that you inattention to detail almost caused the loss of an aircraft and your life. If you had passengers on board at the time of the jam then endangering them is nearing the threshold for criminal negligence.

This furthers the continuing narrative I preach about the importance of not only doing a good preflight inspection but having a strong understanding of what you are looking for and being able to modify the inspection to suit the circumstances. So in the context of this discussion an aircraft that just had a ton of radio work done is going to get a very good look under the panel to make sure there is no wring that could interfere with the control columns or if the elevator was just replaced then all the fittings in the tail are going to get an especially detailed look.

The next theme speaks to the absolute requirement to maintain control of the aircraft. This means that in the event of any suspected control problems apply the minimum use of the controls to maintain a approximately level pitch attitude and with the wings as near to level as possible. Changes in power need to be carefully considered and every thing should be done slowly and carefully. Once control is lost the chance of regaining it with compromised controls will be much lower and the likely hood of a fatal crash much higher.

The last theme is a continuation of the discussion on engine failures. Like an engine failure a jammed/disconnected control is a full on emergency. The only priority is to not injure yourself or the passengers. The condition of the aircraft when it comes to a stop is utterly irrelevant. The accident record clearly shows that the survivable crashes are those where the aircraft contacts the ground wings level, in a level pitch attitude, and with some room to de-accelerate (ie it is not hitting a solid immovable object straight on at speed). Therefore in the event of a jammed control returning to an airport may not be the best course of action. If the aircraft is under control and there is a nice stretch of field right in front of you a slow descent to that field may be a better idea than attempting to manoever back for a landing on an airport runway.

Finally I regret my rather snarky comment suggesting Andrew pm Memphis_Bell
a well known pprune troll.

I would not like to be responsible for contributing to casting a chill over this forum and thus discourage new new pilots from asking questions and thus benefiting from the very considerable experience of many posters here. I of course represent only one view point and my contributions are worth exactly what you paid for them :)

[foxmoth]

BP, unlike you I think this is an appropriate subject in the PPL course, best done in the later stages and one of those items that can be done over coffee on a dud day, I also teach an Advanced PPL course, basically covering in more depth those areas that PPLs are normally weak in and introducing them to a couple of other bits that they probably have not seen so far, this is always a good thing to talk over on that course.

[abgd]

I suppose two related things we discussed during my recent ppl were control locks left in situ, and reversed controls. For the former, I think the comment was that it was an embarrassing way to die; for the latter that you could sometimes survive just by leaving that control centralised and making do with whatever's left.

[foxmoth]

Depends what is reversed, ailerons maybe, elevator or even rudder I doubt you would even get off the ground!

[andrew172]

You mean being reversed from a maintenance error, if they were connected the wrong opposite way?

[mary meagher]

Some power pilots are quite surprised to learn that glider pilots don't require the services of an accredited engineer to

1) Remove and replace the wings.

2) Remove and replace the elevator

3) Attach all controls, and confirm that they have been properly installed with another person to double check it has been properly done by walking round the glider and resisting the pilot's control imput, holding the ailerons, the airbrakes, the elevator, and the rudder, ( though that is usually left installed during road transport.)

It is important that THESE CHECKS MUST NOT BE INTERRUPTED BY ANYONE OR ANYTHING.

We do this every time we take that beautiful bird out of its box.

A bit sad that all this sort of thing with your standard spam can has to be done by a firm of engineers - and that any pilot with a sense of self-preservation has to double - nay, treble his inspection after such maintenance to make sure they haven't screwed up!

May I recommend, if somebody can name the source, the video of an amazing circuit flown by a Russian airliner, recently reassembled from cannibalised parts, in which the ailerons were installed wrong way round.....they eventually worked out the problem and got it back on the ground in one piece.

Now my personal experience of difficulty with control function was a flight to 18,000 feet in wave. It had rained the night before, the glider had been left outside, rigged, and the aileron tape, at altitude, froze quite solid! So my turns to stay in the wave system were done with rudder alone, quite gingerly, and of course the problem solved when we got lower, and warmer.

There have been a number of cases when a glider elevator has been jammed, usually because some numpty has dropped his camera into the declevity, or in one case a paraplegic passenger's wooden seat cushion jammed full aft movement of the stick. The highly experienced instructor did not express alarm - you NEVER express alarm to a passenger! but their approach was seen to be rather faster than normal.....no harm done. It was his fault for not doing a proper full and free control check before taking off.

So the moral of this narrative is - thoroughly inspect the controls before flying, and if something alarming happens when you are aloft, KEEP CALM AND CARRY ON!

Of course, however, we do wear parachutes.....

[peterh337]

After the Annual is done, I always get the maintenance firm to leave inspection covers off and I go around with a light and check everything is secure. Then it goes outdoors, I do the ACF50 treatment (a right messy job) and they put the covers back on.

Reversed ailerons should be obvious during the full and free controls check - they should move opposite to the yoke.

a Russian airliner, recently reassembled from cannibalised parts, in which the ailerons were installed wrong way round

It beggars belief that one would get that far without anybody checking. Maybe the pilots cannot see the control surfaces from the cockpit.

[abgd]

You mean being reversed from a maintenance error, if they were connected the wrong opposite way? Something like that... Though I have to wonder whether the 'wrong opposite way' means that the elevator is connected to the rudder pedals and vice-versa, and both work backwards. I was just thinking of reversed elevators i.e. you pull back the stick and the nose goes down.

There have been at least a few recent accidents involving reversed controls. One was a taildragger that got airborne as soon as power was applied, then stalled when the pilot tried to push the nose down. Another was a chap who'd done his own maintenance, and asked to do some fast-taxis prior to getting the work signed off. He got airborne and immediately crashed, again killing himself. As I recall, it was the elevator reversed in both cases.

Both my instructor and I had rather less significant adventures with radio-control aircraft and reversed ailerons. I crashed straightaway. He left the ailerons centralised and did a circuit using rudder, elevator and throttle only.

[piperboy84]

Mis rigged story

PLACING BLAME AT ANY COST - TIME (http://www.time.com/time/magazine/article/0,9171,135113,00.html)

[Pilot DAR]

I think this is an appropriate subject in the PPL course

Yup, and it is required for the helicopter PPL. Both no pedals, and stuck pedals, and generally right through to a landing that way. I have been amazed at the demonstrations of skill and finesse in this regard shown to me by instructors.

Simply the discussion of the topic is worthwhile. Following a previous post of the same story I presented at the beginning, another PPRuNer posted that in that situation, (high downforce required to maintain control) just put the plane into a tight turn, and left the g balance out some of the pitch force. You might not solve the problem, but you can at least get a break while you figure out the next step - simple! Why had no one ever told me that during training?

[Big Pistons Forever]

I hope I did not give the impression that any discussion of the jammed control scenario should be omitted from PPL training. Rather I personally do not explicitly raise it because ab initio training should follow a progression from simple to complex.

In the context of emergencies this means the progression is from the most likely and most dangerous emergencies to those which are less and less probable.
Since there is never unlimited time to teach everything during the PPL, in practice I have found that achieving proficiency on the common emergencies will require the whole course. I strongly believe that an air exercise of jammed controls given to a student that has not mastered all the common emergencies is negative training.

However as a rainy day brain teaser to a good student this subject might have some real value. But again I strongly feel it should be presented in away as to reinforce good operating practices. The backwards control scenario is an example of something that may have to be dealt with in the air but is fundamentally a complete failure of the pilot to take an obvious and basic precaution of checking the controls for correct movement prior to taking off.


The only caution I would give when discussing the jammed control scenario is that this emergency is susceptible to an unwarranted emphasis on the "hero pilot" school of handling an emergency. That is the the only way to save the day is some fancy stick and rudder work and if successful then it was because "I proved I was a hero pilot".
It's a sexy and alluring dialogue.

The only problem is if the student winds up crashing an aircraft, it won't be because his hero piloting skill was deficient it is going to be for the usual unsexy reasons like running out of gas, letting carb ice build to the point of engine failure, losing control during takeoff or landing, running off the end of the runway etc etc.

I guess that is why I had an immediate and visceral response to Andrew172. The number one problem in GA right now IMO is a lack of proficiency in the piloting basics and a lack of understanding of the aircraft and its systems and performance. Those foundation skills and knowledge need to be the emphasis of primary flight training and until fully developed make training in advanced concepts of little practical value.

One of my favorite "emergencies" with PPL's nearing the end of their training (and CPL's too) is to cover the airspeed indicator when the aircraft is in the practice area. The student has to fly back to the airport and land with no airspeed reference. All the skills needed to fly the aircraft were taught in the first flying lesson, attitude plus power equals performance, and it is a wonderful demonstration of the fact that everything you need to fly the aircraft is available by simply looking out the windscreen. When they are settled on final approach and have the runway made I ask them what they think their airspeed is. I then uncover the ASI and I have never had a student out by more then 5 knots :ok:\

I am not a helicopter pilot but my impression was that many of the "no pedal" exercises pilot DAR mentions are being phased out of helicopter training because many more helicopters were being crashed in training then had ever crashed after real tail rotor/pedal failures....

[Chuck Ellsworth]

Yup, and it is required for the helicopter PPL. Both no pedals, and stuck pedals, and generally right through to a landing that way. I have been amazed at the demonstrations of skill and finesse in this regard shown to me by instructors.

How are things going for you Pilot DAR?

For me life is gradually returning to some semblance of normal since Pene passed away in the fall of 2010.

The Cub project I had in my garage has not progressed very much since you were here, but I am finally going to finish it now.

With regard to the discussion here I decided to comment because of the above comment by you, as it in my opinion addresses the difference in the quality of flying instruction in the world of rotary wing flying compared to fixed wing flying.

Looking back on my career it was my experience that the quality of instruction in the rotary wing sector was better because the experience level of rotary wing instructors was far higher than in the fixed wing world....I don't recall knowing any rotary wing instructors who were teaching students without having any experience flying commercially before they became instructors.

Do you know any?

Chuck Ellsworth.

[Pilot DAR]

I don't recall knowing any rotary wing instructors who were teaching students without having any experience flying commercially before they became instructors.

I agree with your observation Chuck. I had not though of it that way, but I think you're quite right. One of my two instructors (who had a lot more grey hair than I) told me that during helicopter instructor seminars he used to ask Transport Canada why only stuck pedals, and not stuck cyclic and collective, were taught and examined. Apparently no answer was forthcoming...

Life is excellent, and I expect to be along in the next week or two, to tell you all about it in person. I also plan to meet up with another rather famous V.I. PPRuNer. I'll be in touch....