Teaching Stalls in Wing Heavy Aircraft....

[aviator1978]

There's an older 172 at my flight school with a heavy left wing. In cruise flight, in order to fly hands off, rudder input has to be such that the ball is deflected to the left, fully outside the "window". As such, the rudder trim tab has been bent to accomplish this wings-level cruise flight.

It's all fine and dandy, till I start teaching students stalls. Keeping the plane coordinated (i.e. ball centered) and wings-level during power-on stalls requires nearly full right aileron deflection at the stall and a quite sudden wing drop. This never seems to make my students very happy.

What I've been showing the students, is to keep the ailerons neutral through out the approach to the stall, and use the rudder to keep the wings level. The plane will then stall straight forward, with the ball deflected.

Is this the right method?

A student asked me why this "uncoordinated" stall results in a better recovery. Quite honestly, I don't know the answer. Why is this? As far as I can tell there isn't any installation error in the inclinometer.

I'm sure some responses will be to tell the maintaince to fix this. Believe me, I have.

 

[NW_Pilot]

There's an older 172 at my flight school with a heavy left wing. In cruise flight, in order to fly hands off, rudder input has to be such that the ball is deflected to the left, fully outside the "window". As such, the rudder trim tab has been bent to accomplish this wings-level cruise flight.

It's all fine and dandy, till I start teaching students stalls. Keeping the plane coordinated (i.e. ball centered) and wings-level during power-on stalls requires nearly full right aileron deflection at the stall and a quite sudden wing drop. This never seems to make my students very happy.

What I've been showing the students, is to keep the ailerons neutral through out the approach to the stall, and use the rudder to keep the wings level. The plane will then stall straight forward, with the ball deflected.

Is this the right method?

A student asked me why this "uncoordinated" stall results in a better recovery. Quite honestly, I don't know the answer. Why is this? As far as I can tell there isn't any installation error in the inclinometer.

I'm sure some responses will be to tell the maintaince to fix this. Believe me, I have.

My, 150M did that when I first purchased it, I solved the problem by taking the bird in and having it completely re-rigged now I can do most stalls with out any or very little rudder usage.

 

[avbug]

Aviator1978,

What kind of example are you giving your students by teaching in this airplane? A very bad one. You should lead the pack by showing your students that as an educated professional, you're prepared to reject an unairworthy airplane. Squawk it, get it rerigged so that it flies properly.

There's no such thing as a "heavy wing." The aircraft is misrigged. Or damaged. Has someone overstressed it, and does it have hidden damage? Is a flap dragging? Something, somewhere is causing this flight condition, and it could range from improper flight control rigging to a control balance issue to a damaged engine mount.

Forget about seeking proper technique for teaching in the airplane...think about w(h)eather you should be teaching in it in the first place. Get it fixed, show the students proper decision making on your part, then continue teaching those stalls.

You're sure some responses will tell you to tell maintenance. I'm not telling you that at all. Yes, you've told maintenance, and maintenance hasn't done anthything about it. You don't have control over that. But you do have control over w(h)eather you continue setting a bad example for students by accepting this condition. I'm not telling you to tell maintenance, I'm telling you to insist, and to set a proper example as both instructor and PIC. Good luck.

 

[aviator1978]

Avbug, it's easy to say that, and in fact, I used to avoid flying the plane. But it's Christmas, student loans, and rent is due. Gotta make the money somehow.

I let students know about the problem, but since the plane is $15 cheaper an hour than our new SP's, they usually accept it anyway.

Such is aviation today.

But, back to the original question....Why would it stall benignly in uncoordinated flight?

 

[aucfi]

But, back to the original question....Why would it stall benignly in uncoordinated flight?

Tough question. There are so many aspects that have to be considered, mainly the aircraft's rigging and structural integrity. An out of rig airplane or structurally damaged airframe may fly normally, but stall very differently than what’s to be expected.

I used to fly a J3 that looked normal on the outside but actually had three cracked ribs and wing tip bow from ground loop accidents. We found them during a recent restoration. It would require a constant deflection of aileron while in cruise but would stall gently (eh, it’s a cub I know).

I often fly a 172 that is slightly out of rig according to the mechanics but not bad enough to justify re-rigging the whole thing. The controls have a little bit of slop in them but the stalls are predictable and can break left or right if you are uncoordinated as such. Each type of airplane generally stalls the same but with minor differences. In the case of the 172 you’re teaching in, it sounds like its own breed when it comes to stalling.

I agree with avbug and believe me, I understand your situation about Christmas, student loans, and rent but you got to ask yourself, is it worth it? What are your students gaining from learning stalls in an airplane that stalls its own way? Certainly don’t want to waste their time or money in an airplane that is that unpredictable and possibly dangerous.

Have you suggested to your students to take their lesson on stalls in the SPs and spend 15 extra bucks for just that lesson? If they have that much of a problem with the stall characteristics of that 172, they shouldn’t be bothered with an extra $15 for one or two lessons.

Merry Christmas

au

 

[NW_Pilot]

Aviator1978,

What kind of example are you giving your students by teaching in this airplane? A very bad one. You should lead the pack by showing your students that as an educated professional, you're prepared to reject an unairworthy airplane. Squawk it, get it rerigged so that it flies properly.

There's no such thing as a "heavy wing." The aircraft is misrigged. Or damaged. Has someone overstressed it, and does it have hidden damage? Is a flap dragging? Something, somewhere is causing this flight condition, and it could range from improper flight control rigging to a control balance issue to a damaged engine mount.

Forget about seeking proper technique for teaching in the airplane...think about w(h)eather you should be teaching in it in the first place. Get it fixed, show the students proper decision making on your part, then continue teaching those stalls.

You're sure some responses will tell you to tell maintenance. I'm not telling you that at all. Yes, you've told maintenance, and maintenance hasn't done anthything about it. You don't have control over that. But you do have control over w(h)eather you continue setting a bad example for students by accepting this condition. I'm not telling you to tell maintenance, I'm telling you to insist, and to set a proper example as both instructor and PIC. Good luck.

I know during the rigging on mine we ended up having to unbolt the right wing and move it a little till the laser made a tone. we also Adjusted the rudder cables tension ect. Been almost 2 years and I have stressed this little bird a bit you know the usual spins, rough grass strips, lots of power on, off, turnning stall’s it still fly’s straight as an arrow hands and feet off. Make sure who ever Riggs the bird dose it correctly and with modern updated tools & instruments worth the money spent takes about 3 full days labor. If there is no physical damage to the bird & it is not something you want to rush.

 

[nosehair]

There's no such thing as a "heavy wing." The aircraft is misrigged. Or damaged. Has someone overstressed it, and does it have hidden damage? Is a flap dragging? Something, somewhere is causing this flight condition, and it could range from improper flight control rigging to a control balance issue to a damaged engine mount.

Forget about seeking proper technique for teaching in the airplane...

Unfortunately, in the real world, there are "heavy wings". As Avbug mentions, there are many reasons, but the bottom line is, that we should be able to handle a "misrigged" airplane in stall/near stall conditions.

We do need to seek proper tecniques to handle the "unexpected".
We all can learn from this experience by understanding and promoting the basic concept that the ball is not going to be centerd in a properly rigged airplane either.

That's why the airplane stalls better when you keep enough right rudder to keep the nose straight. When you hold exactly enough right rudder to overcome P-Factor, and hold the wings exactly level with the aileron, the ball will be deflected slightly to the left. In your 172, this deflection is extreme, and you are experiencing an extreme stall reaction, but the concept is the same. This is actually a good teaching tool. Although, as Avbug points out, it may not be a safe tool. It needs to be fixed.

But when you have significant angle of attack and high power in a single-engine airplane, you have P-Factor, which moves the thrust line to the right, much like asymmetrical thrust in a multi.

Although on a smaller scale, it is still enough to make it impossible to "keep the ball centered" during stalls. The true focus should be on holding a constant heading with rudder pressure, and wings level with aileron pressure. And these pressures will vary according to the quality of rigging in the airplane. In a properly rigged plane, the ball will be slightly out, depending on the horsepower; and an improperly rigged plane will be way out to the point of not having enough rudder to keep the nose straight or ailerons to keep the wings level. But, that is the focus; not keeping the ball centered. You can't.

Turning stalls is a different story. That's when you want to keep the ball centered. Keeping the ball centered with rudder, and the angle of bank constant with ailerons. As constant at a specific bank angle as you were focused on keeping the wings level in straight ahead stalls.

So the scan changes from focusing on ball control with the rudder during turns. Straight ahead, hold the heading with rudder. Turning, hold the ball centered with rudder. In both cases, hold the bank angle with the ailerons. Either level or a specific angle.
​

 

[aucfi]

Unfortunately, in the real world, there are "heavy wings". As Avbug mentions, there are many reasons, but the bottom line is, that we should be able to handle a "misrigged" airplane in stall/near stall conditions.

We do need to seek proper tecniques to handle the "unexpected".
We all can learn from this experience by understanding and promoting the basic concept that the ball is not going to be centerd in a properly rigged airplane either.
​

Well said Nose Hair. As far as a heavy wing; I was working on a 172 this past summer that had a 5 pound iron bucking bar in the right wing near the wing tip. Who knows how long that had been there. Mechanics leave tools, birds and insects build nests; airframes put on weight in all the wrong places. Also its not uncommon for a 172 to unevenly burn fuel from the wing tanks. Both does not mean "equally".

In my opinion, safely handling the unexpected comes with mastering the expected. Inclometers are not always 100% acurate. Take dutch rolls for example. If you keep the nose exactly on whatever your rolling about, take a look at the ball and see how out of whack it is. Anyone teach dutch rolls anymore?

I have heard examiners say they judge coordination through the seat of their pants and others who strictly use the inclometer. Either way, coordinated flight can be felt through the seat of your pants, yoke/stick and rudders with experience.

au

 

[avbug]

Avbug, it's easy to say that, and in fact, I used to avoid flying the plane. But it's Christmas, student loans, and rent is due. Gotta make the money somehow.

Justification is the narcotic of the soul.

Apparently you are an addict. Good luck with that.

 

[NW_Pilot]

Justification is the narcotic of the soul.

Apparently you are an addict. Good luck with that.

Step 1
You admit you are powerless over aviation/flying - that your bank account has become unmanageable.

 

[Singlecoil]

I used to fly a 207 that was very wing heavy. One solution was to keep only 30 minutes of fuel in the heavy wing and top off the other. That might help your situation.

 

[avbug]

I used to fly a 207 that was very wing heavy. One solution was to keep only 30 minutes of fuel in the heavy wing and top off the other.

That's one soloution.

Another is GET IT FIXED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[paulsalem]

Or you could look at this "problem" in a different light.

Bascially you have an aircraft that has a built in x-wind landing system (that is operational roughly 50% of the time).

Imagine if you could purchase such a feature on an aircraft. The extra option would cost tens of thousands.

:-D


But seriouslly, get it fixed.

 

[taloft]

I'm going to assume that you have checked with maintenance about this and have yourself determined that it is safe. You should also check with the chief pilot if you have one. Obviously, excessive wing drop is not something to take lightly.

Avbug is correct that there may very well be times that you have to refuse an aircraft that someone else says is OK. As PIC, you have the authority to do this and the responsiblity to make the right decision.

If we're just talking slight wing drop (and the airplane is airwothy and safe), I'd see it as a good opportunity to teach the students how to do stall recoveries properly by using the rudder to level the wings (rather than ailerons). Need to break that habit of always using the ailerons to recover, especially in early stall recovery practice.

On the other hand, I'd certainly supplement this with stall practice in an airplane that doesn't have this tendency. Don't want to get them in the habit of mindlessly stomping right rudder every time they stall (obviously).

In short, teach them to respond to the airplane during the stall. Different airplanes will stall differently and only proper recovery technique for the situation is appropriate. It's best they learn this kind of stuff while you are there.

In reality, your students may go out one day and unknowingly rent an aircraft with wing drop (low wing/switchable fuel tanks perhaps) during a stall. Yes, we teach stall avoidance and they should never stall it. However, there is a reason we teach stall recoveries and accelerated/turning stall recoveries. Wouldn't it be nice if they at least had some basic practice beforehand?

Also, avbug is "spot on" in that you must teach students proper pilot judgment. It's possibly the most important thing you will EVER teach them. Good decision making doesn't include stuff like "rent is due" or "fly because it's Christmas." I suggest you use these with your students as good examples of how not to make decisions.

One of the great things about being an instructor is that your students will do exactly what you do: both the good and bad. You owe it to them and yourself to keep the good and get rid of or change the bad. Perhaps you weren't taught everything correctly from your instructors. It happens. I had great instructors, but after becoming an instructor, I realized there were a few bad things I had to throw out when a student mirrored it back for me. Heck, I'm still working on my technique/judgment every flight even when not instructing. Be an example for them so they won't have to change much when it's their turn to teach. Consider yourself training a future instructor (from the first student hour) and all the pilots they will train, not just a future pilot.

 

[Midnight Flyer]

Aviator1978,

What kind of example are you giving your students by teaching in this airplane? A very bad one. You should lead the pack by showing your students that as an educated professional, you're prepared to reject an unairworthy airplane. Squawk it, get it rerigged so that it flies properly.

There's no such thing as a "heavy wing." The aircraft is misrigged. Or damaged. Has someone overstressed it, and does it have hidden damage? Is a flap dragging? Something, somewhere is causing this flight condition, and it could range from improper flight control rigging to a control balance issue to a damaged engine mount.

Forget about seeking proper technique for teaching in the airplane...think about w(h)eather you should be teaching in it in the first place. Get it fixed, show the students proper decision making on your part, then continue teaching those stalls.

You're sure some responses will tell you to tell maintenance. I'm not telling you that at all. Yes, you've told maintenance, and maintenance hasn't done anthything about it. You don't have control over that. But you do have control over w(h)eather you continue setting a bad example for students by accepting this condition. I'm not telling you to tell maintenance, I'm telling you to insist, and to set a proper example as both instructor and PIC. Good luck.

Maybe that aircraft was the only one available on that day. I think instead of saying he's giving the student a bad example by using this plane, maybe he can show the student that all planes fly a little different and stall a little differently. Or maybe on that day, practice something other than stalls, and write the aircraft up after you land.
Alot of the 727's that I fly and have flown do not fly straight. That does not mean it's not airworthy and I'm not going to call maintenance and refuse a trip because of it.

 

[avbug]

Maybe that aircraft was the only one available on that day.

More of that soul-narcotic, again. Yes, the aircraft is unairworthy. Yes, it's a bad example for the student. But it's christmas. But it's the only one that's available. But I have to pay rent. But I'll justify it because...because, because, because, but, but, but.

If you try hard, you can justify anything.

Or maybe on that day, practice something other than stalls, and write the aircraft up after you land.

More narcotic. We'll accept it this time and write it up when we land. That is, you already know it's got a problem...if it's enough of a problem to write up when you land, why are you taking it to begin with???

Alot of the 727's that I fly and have flown do not fly straight. That does not mean it's not airworthy

Of course, you know this from studying the aircraft maintenance publications...and you know that airworthy means A) in conformity with approved data (AFM, Mx pubs, AD's, STC's, etc), AND B) is in safe condition for flight. If it doesn't meet both of those criteria, then it's NOT airworthy.

There's an older 172 at my flight school with a heavy left wing. In cruise flight, in order to fly hands off, rudder input has to be such that the ball is deflected to the left, fully outside the "window". As such, the rudder trim tab has been bent to accomplish this wings-level cruise flight.

It's all fine and dandy,

Good luck finding the Mx specifications in the Manufacturers approved publications for rigging an airplane that flies like that, to fly like that...I was handed a C-182 a few years ago prepatory to an annual inspection. One of the things the DZ's regular pilot commented about was that the control wheel required almost full deflection one way to maintain wings level. I approached the IA who had done the work the previous year and signed off the annual, as well as signing off having rigged the controls. His response was that the aircraft just needed a lot of rudder trim to make it fly straight, and not to worry about it. I had to re-rig everything, and I've never seen an aircraft so far out of rig or specification (excepting a couple that have had the ailerons rigged backward).

The Type Certificate Data Sheet calls out specific control deflections, and the maintenance manual echoes the TCDS, as well as giving a number of specifics regarding the rigging of the aircraft. If the aircraft is not in conformity with this data, then the aircraft is NOT airworthy.

 

[Kaman]

Hello,
Where I flew 135 cargo, it wasn't uncommon to have an airplane that was rigged a little out of whack, but never to the point that I felt safety was compromised. And, some careful fuel planning/burning made for a comfortable day of flying. In an ideal world I'd have had them fix it, but an ideal world I didn't live in.
Addressing the stall issue, it's why you teach RUDDER, RUDDER, RUDDER for recovery from a stall. A common reflex is to get on the ailerons and correct for the wing drop. A No-No in the Sundowner especially. I used to teach students to use nothing but rudder all the way through the recovery, because this will keep the airplane coordinated and as any student pilot should be able to tell you, An uncoordinated stall leads to a spin... my humble .02 cents.

Regards,

ex-Navy Rotorhead

 

[pianoman]

In the EMB-145, we have two ball inclinometers and an electronic one on the stby. AI. It's not uncommon to have three different readings. So there's a pretty good chance the one in your 172 could be off. So if you stall it according to that, maybe you ARE actually uncoordinated.

Sucks, I know.