rudder/steering issues

[chopperholic]

Hi

I'm a new PPL and but have been flying for two years since starting training. I have noticed an issue during the ground roll where the aircraft wants to drag itself to one or the other side of the runway. Crosswind you might say but this happens on occasions even in VERY calm wind situations. Landed the other day and found myself putting in full right rudder to keep the thing straight and I had the sensation it wanted to tip over even though I slowly squeezed in the rudder and used aileron to keep the wing down despite it being almost nil wind. I was with a passenger of equal weight and we're not overweight! Everything about the landing was normal, flare fine, held weight off nose and gently lowered and landed on centre line etc.

Normally I would suspect the tyre/inflation which are all fine. Undercarriage looks fine and I have to say this doesn't always happen so I don't think anything is bent. The same thing used to happen in the cessna I used to fly but again only very occasionally. Not sure what is going on or if I'm doing something wrong! I thought maybe it could be fuel sloshing around as it was almost full tanks?

Aircraft is a Piper Warrior of 1998 vintage and in very good condition albeit it is a training aircraft at my club. Sorry if this sounds like a silly question but its a srange anomaly that concerns me!

Would be interested in any thoughts!

[john ball]

Are you sure that you have just the ball of your feet on the bottom of the rudder pedals. If you have big feet and are wearing large trainers, you may not feel that you are actually touching the top of the pedal and putting on some brake. I never wear large shoes when flying as it is not really possible to feel or stretch the toes out. Light plimsoles or deck shoes are best.

[FlyingStone]

Hm, quite strange. The Warrior does have a nose-wheel steering connected to rudder pedals (unlike Diamond/Cirrus and some other aircraft), so the required rudder input would be noticeably less than without the steering (while the nose wheel is one the ground of course). Even if the nose wheel steering would be inoperative (which I think you would notice during taxi), I don't think you would need full (or any significant) right rudder deflection - left rudder perhaps, but right rudder requirement seems a bit off (assuming right-hand prop rotation which most SE aircraft have). Usually with single-engine aircraft you have to give it a bit of left rudder when you retard throttle to idle before flare, since the engine isn't producing as much torque as it did during powered approach, but the fixed trim-tab on the rudder is still pushing the aircraft to the right, since it's usually set for cruise power/speed. I just remembered that some PA28s (perhaps all) are equipped with rudder trim, so you should ensure you're using the correct setting (if I remember correctly, I think for takeoff and landing it should be somewhere between center and quarter of full right deflection).

Given that the problem isn't as usual, I would do the next things:
- check the rudder trim tab / rudder trim setting before landing
- the amount of rudder (left or right) you are required during different phases of flight (takeoff just after rotation, climb, cruise, descent, approach, flare) to keep the ball centered
- ask the other pilots (preferrably someone more experienced) who fly the plane if they notice anything unusual: and if they don't, ask them to tell you how they fly the aircraft to do so
- have a chat with somebody in charge with maintenance of the aircraft, perhaps they know something you don't

P.S.: 1998 Piper Warrior is not vintage, in the spam-can GA market it's almost state of the art aircraft :)

[Pilot DAR]

Chop,

Without wanting to doubt what you wrote, are you sure to had full rudder in? It can be a bit intimidating to apply FULL pedal. I think back to crosswing testing I was doing in a modified Cessna Caravan last winter, where I purposefully chose a runway which had the 90 degree crosswind, with a steady 26 knots. Once on the ground, it did take full and sustained application of pedal to keep it straight, but it did it, as advertised. I did leave some rubber behind doing it!

If you are actually getting full pedal in (and no brake on either wheel), and that will not overcome a drift in the other direction, you have a maintenance issue. Rudder trim will not be a factor, you can overpower it.

Make the most of the rudder itself. Once on the runway firmly, hold the nose light with stick back, to the point where you have full nose up control in. That will let the rudder do it's job, in spite of what the nosewheel might be trying to do. Once the stick back will no longer hold the nose light, the rudder is of little use either, so you're fully into the steering. The aircraft should track mostly straight without much effort.

Though Pipers are pretty straight forward for nosewheel steering maintenance, I have flown Cessnas with "maintenance fail" nosewheel rigging, which were quite alarming to steer.

To challenge yourself, go and take an hour of compotently trained tailwheel circuits, you might rethink pedal use after that!

Good luck, keep to the straight and narrow!

[Pace]

Choperholic

We think of landing winds as being constant but sometimes we have gusty conditions or even changing winds as they pass between hangers, trees etc.

If you are nervous or not confident it maybe that you are not reacting enough and then over reacting rather than squeezing in the right amount of aeleron and rudder in one smooth actiion.

I used to race cars and the secret was being smooth good speed judgement and feel.
Under and then over correcting a car will cause no end of problems as the car becomes unsettled.

The same goes with the aircraft! Are you undercorrecting and then panic overcorrecting rather than smoothly applying the right amount of pressure for the conditions.

Its the same with breaking! Jump heavy footed onto the brakes the weight will go forward, that in turn will effect the pitch angle of the wing while making the rear wheels lighten up.

I dont think its a maintenance problem but one where you need to feel confident controlling the aircraft and not feeling the aircraft is in control of you.


Pace

[Whopity]

Centralise the Rudder Trim!

[NutLoose]

Make sure the nose strut isn't over inflated or sticking, when the strut is extended in flight the torque links are designed to sit against a flat on the main nose strut keeping the nosewheel straight ahead and "breakout" springs in the steering rods allow the rudder bar to move still, if over inflated then the noseleg is in effect locked straight ahead, so you have only rudder input to keep it going in the direction you want and no nosewheel steering, either that or it could be a draggy brake. Goes for both Piper and Cessna, though some Pipers do have solid rods on them.

[Big Pistons Forever]

Sounds like a dragging brake on one side. This can be a bit hard to detect on taxi in Piper singles because of the direct nose wheel steering system, but will be very noticeable on roll out.

[Ultra long hauler]

- have a chat with somebody in charge with maintenance of the aircraft, perhaps they know something you don't

Yes, that would be my 1st step too!
Before posting on PPrune, even!!


- ask the other pilots (preferably someone more experienced) who fly the plane if they notice anything unusual: and if they don't, ask them to tell you how they fly the aircraft to do so


Bingo! I think that is where the real key lies!
Mx-department may not know, otherwise they would have fixed the issue I guess. After all, they may not fly the aircraft themselves.
For me, the main issue would be, if YOU are the only one or are there more people struggling with this particular airframe??

If everybody else is fine with it…….well, maybe you should look closer to home.
But if others (more experienced) have issues, it is worth pulling the whole steering system apart if need be!!

###Ultra Long Hauler###

[mikehallam]

Daft question back from me.
You are landing on the main wheels first and not on all three ?

mike hallam.

Seems the above sentence can be misunderstood.

I was asking if the P1 was NOT landing on the mains first, but doing a minor wheelbarrowing ?

[Pilot DAR]

You are landing on the main wheels first and not on all three ?


If you got all three wheels on the ground at the same time in a PA-28, you'd have to be going so fast that the rudder would be "steering" the plane very well, the nosewheel would have less to do with it.

Letting alone the steering issues, three point landings in a PA 28 (or any tricycle aircraft) are a bad idea.

YouTube - ‪Bad Landing‬‏ (http://youtu.be/C1fFrEuuMF8)

[I Love Flying]

Please can you try putting up your links again Pilot DAR? Or am I doing something wrong?

Cheers.

[mad_jock]

See if this works

YouTube - ‪Bad Landing‬‏

It doesn't seem to like embeding the video

[Pilot DAR]

Thanks MJ, any idea what I did wrong?

[mad_jock]

I think youtube has done some changes and there is a slight protocol issue with embedding youtube links when linking into BB software.

I had to butcher it somewhat to get it to work.

So its not your fault.

[I Love Flying]

Thanks Pilot DAR for sending it, Thanks MJ for sorting it!:D

An eye-opening video....

[mad_jock]

yep also allows you to learn how to say farking hell in Swahili although it does have the ring of a safa boer about the turn of phrase.

[Tinstaafl]

What's the rudder trim setting when you experience the behaviour?

[Pilot DAR]

Let's remind ourselves that the rudder trim, like any trim, is not a control travel limiting system. Therefore, regardless of it's setting, you will still have the full travel of the control available to you. Thus, a miss trimmed aircraft is not a reason to not be able to control it, it just may take some more muscle.

That said, in a recent test flight I did in a Warrior, I did not find the rudder trim to have a tremondous affect on the rudder forces required, as is generally the case for single engined aircraft with rudder trim.

Unlike a Cessna, the Pipers have direct nosewheel steering. Therefore, if, while moving on the ground, you start applying full pedal, you should end up zigzagging all over the place. (avoid, they'll bring out the breathalyzer when they see you). However, once in suitable flight, and safely between 1.4Vs and Va, there's no reason to not get used to the feel of FULL rudder deflection. You can put all the way in, and hold, while you apply opposite aileron, just to get the feel.

Years ago, I had to check myself out in a Bellanca Viking (300HP, four place low wing). I found directional control during takeoff much more difficult than I expected. I attributed it to torque, as the landing was perfectly fine. Then, I was into a runway, where a more soft field takeoff technique seemed appropriate, and it went perfectly. It turned out that I had had the plane trimmed to the wrong end of the pitch trim "takeoff" range, and it was very sensative to that when solo. I had been wheelbarrowing it with takeoff power. When I trimmed way nose up, and kept it light, things went perfectly. After a technique change (which I should have been doing all the way along anyway), no problem!

I was flying a Twin Otter for the first time in many years, a few weeks back. They have a less than desirable nosewheel steering system - a lot of finess required, and over controlling very easy. If doing a short takeoff by yourself, it pretty well requires three hands. I confirmed with my mentor pilot that once perfectly lined up, and with no particular crosswind, the rudder was enough, and streering was not required. He confirmed that. I was not long before I was doing circuits on a rather short and narrow turf runway (just the perfect place for fun in a Twin Otter!). There were some gentle mountain breezes, but nothing which would alarm me. There I was, however, accelerating down the runway with full left pedal, gently going onto the grass on the right side. I suppose it was not alarming my mentor, as he was not helping. Problem was, at this point, you have to undo something fast. Either let off rudder pressure, so you can get you toe up to the brake (bad idea), let the nose back down, so you can reach the nosewheel steering after all (messy, but doable), or start reducing power on the left side. I elected to pull back a bit of power, as I faintly yelled "help!", and I felt a bit of left brake being applied for me. It worked out fine, and my mentor did not seem alarmed, but I was! He agreed that I had had full pedal in, and that should have been lots, but stuff happens! I have a new respect for those pilots who fly Twin Otters into those 50 foot wide runways in the mountains!

Anyway, I've drifted your thread.... Always satisfy yourself that if you might be needing it, you have FULL control applied, it's there to be used when needed. Designers purposefully assure that what you have is what you need, the plane won't swap ends on you!

[FlyingStone]

However, once in suitable flight, and safely between 1.4Vs and Va, there's no reason to not get used to the feel of FULL rudder deflection.

May I humbly ask where does the 1.4Vs come from? And I assume this is probably CAS, since using full rudder puts you way out of coordinated flight, sideslip angle increases and thus the dynamic component of total pressure sensed by pitot tube decreases?

[Pilot DAR]

I have been intentionally non specific as to IAS/CAS, as I'm not trying to describe a specific speed. Rather, my intention was to suggest a slower speed range, below which flying is not being suggested for the purpose of a newer pilot getting to know the plane, with full rudder application.

I am required to carefully plan and plot speeds, corrections and IAS/CAS for testing, and record what I have observed. However, I don't suggest doing so adds value in this situation. It's just an attempt to give a new pilot some confidence that yes, those controls are intended to be used to the limit in some phases of flight, and here's such a phase...

I agree that full rudder deflection puts you way out of co-ordinated flight, and surely introduces pitot errors. However, if you enter uncoordinated flight at 1.4Vs, and maintain that airspeed or faster, I propose that you will maintain a safe flying margin - particularly in a Warrior.

The standard calls for 1.2Vs to 1.3Vs for this testing, so I would thing the newer pilot is safe at 1.4, even if IAS to CAS is overlooked. This should also cover yaw induced pitot position errors, at least to the point of being safe.

For a King Air B200 project, I was required to verify yaw stability and control at full rudder deflection at 1.2Vs1 CAS. That aircraft has a special condition which describes the possibility of yaw angles as great as 38 degrees. I did not have an accurate means of measureing the yaw angle I achieved, and I don't think I got that high, but it was sure going sideways. A very controllable aircraft, and there did not seem to be position errors which made me uneasy maintaining safe, controlled flight in this configuration. The boom out the back I was testing was sure wiggling though!

My prime thought is that some pilots have not come to relax with the reality that they have a lot more control than they think, if they simply put the intention and muscle into using it. Pilots should not spend their entire flying time, just going straight and level with their chums, or wife and kiddies. They should plan a flight under appropriate conditions, within a safe range, and the aircraft limitations, and see what the plane can actually do. Many would be surprised! (and they'll be safer afterward)

[Mimpe]

a few observations- you are so lucky to fly such a young aircraft!!!

unequal brake friction or untintended unilateral footpedal application could do this
wheel bearing friction might do it
oversteering/overcontrolling might set up an oscillation that you find hard to control
variable power settings on both take off and landing require a continuous variation in rudder pressure that becomes routine with experience
In relation to approach speeds- early after getting my licence I made a few errors that evetaully got corrected.
One was to fly above the recommended 1.3 x stall to minimise risk of loss of control close to the ground.The problem with the is that in both low wing and particularly nose heavy aircraft like the C 182, one would become inpatient and try to fly the aircraft onto the runway well before it was ready to stay there!
I learnt to fly the approach to the exact number i wanted, and there is no better than that recommended in the POH, with a bit more if its very hot.

AircrAft like a Mooney will punish you in ground effect if the approach is too
fast. A good skill is to fly exactly the right number, which may be higher if hot or heavy. Flare techiques are different for Se and Me aircraft but you'll find that out with training. Twins dont float down runways, but tend to just sink into them with grim determination....

[Tinstaafl]

Temperature shouldn't change the approach speed if you're referring to IAS. *TAS*, however, will be greater for that IAS, leading to a faster groundspeed and more runway required.