Aileron range/alignment
Thread Starter
Aileron range/alignment
Hi everyone
I'mstruggling with adjusting the range/travel of my aircraft's ailerons.
I was wondering if there was a standard process or procedure, perhaps used by pro aerospace engineers, to resolve these types of rigging issues.
Mechanically I think the control system (pushrods and bellcranks) in my aircraft is pretty standard:
Any help would be much appreciated.
Thanks
I'mstruggling with adjusting the range/travel of my aircraft's ailerons.
I was wondering if there was a standard process or procedure, perhaps used by pro aerospace engineers, to resolve these types of rigging issues.
Mechanically I think the control system (pushrods and bellcranks) in my aircraft is pretty standard:
- The system comprises a central cable circuit attached to the yoke (with two turnbuckles in the circuit, port and stbd). From the rear of the cable circuit, pushrods laterally down each wing, each of which terminate at a bellcrank which converts the lateral pushrod movement into longitudinal movement of another pushrod (which connects to a horn on each aileron).
- A turnbuckle on each side of the central (yoke) system cable circuit allows the cable to be tensioned and compensatory changes to the turnbuckles allow the 'zero' position to be altered (port or stbd).
- The lateral (wing) pushrods are each adjustable by approximately 12mm (12 threads of a single M6 rose joint, at the wings/ bellcrank end of each pushrod).
- The longitudinal pushrods from each wing's bellcrank to that wing's aileron are adjustable by approximately twice that much (a rose joint on each end of the pushrod).
Any help would be much appreciated.
Thanks
Moderator
Before getting too far into this, is the airplane type certified? Does it have a maintenance manual with rigging instructions? If it is type certified, and does not have rigging instructions (rare, but possible - mine is such), the type certificate data sheet will tell you what the correct flight control deflections are to be. There are a number of safe/standard practices for adjusting turnbuckles (as well as special tools), and cable tension is important, once the rigging is correct.
If the airplane is non certified, the information you seek is a little less certain. Perhaps a type club for that airplane type...
In any case, the answer you seek here could only come with more information on what airplane you're discussing...
If the airplane is non certified, the information you seek is a little less certain. Perhaps a type club for that airplane type...
In any case, the answer you seek here could only come with more information on what airplane you're discussing...
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It would help to know what your aircraft is,and if you have a manual for it,detailing `HOW`.
You should have or make small clamps to hold the ailerons level with the wing surface ,and a method of holding the stick absolutely central.The bellcranks should have rigging pins to hold them at datum.
Its then a matter of measuring all similar pushrods/turns ,equal both sides,and then adjusting the cables equally,but not tensioned fully..Then check ailerons for travel/equal,rinse,check adjust a/rqd.finally,ok tension cables,check,check..or,get a proper `gingerbeer to do it whilst you watch.....simples....
Whatever you do to one pushrod will require other(s) to be adjusted,and the `other side`....Keep note of each adjust ment,ie 1 turn IN/OUT...
You should have or make small clamps to hold the ailerons level with the wing surface ,and a method of holding the stick absolutely central.The bellcranks should have rigging pins to hold them at datum.
Its then a matter of measuring all similar pushrods/turns ,equal both sides,and then adjusting the cables equally,but not tensioned fully..Then check ailerons for travel/equal,rinse,check adjust a/rqd.finally,ok tension cables,check,check..or,get a proper `gingerbeer to do it whilst you watch.....simples....
Whatever you do to one pushrod will require other(s) to be adjusted,and the `other side`....Keep note of each adjust ment,ie 1 turn IN/OUT...
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Thread Starter
Thanks both - it's a Tecnam P2002 Sierra, but not of the factory-manufactured/certified variety, so designated as a P2002-EA Sierra (Experimental). The certified (P2002-JF) and (UK LAA) homebuilt (P2002-EA) versions are structurally identical in this area.
The certified model has a Maintenance Manual which outlines of course the range values etc, as does the UK LAA TADS (type acceptance) document.
Neither of the above provide rigging instructions, the range/extension of the ailerons are far too great and I don't know how to fix that. Other builders don't seem to have had this problem. I'm a step away from thinking my kit - which was the first to be sold in the UK - has some incorrect part(s) supplied, or a manufacturing defect, but I want to try to cover all bases first before I go back to Tecnam in Italy. Tecnam UK has taken several forms since I first purchased the kit in 2005
Correct assembly has been verified, I just can't seem to adjust the pushrods and turnbuckles to sort this out! Thanks again
The certified model has a Maintenance Manual which outlines of course the range values etc, as does the UK LAA TADS (type acceptance) document.
Neither of the above provide rigging instructions, the range/extension of the ailerons are far too great and I don't know how to fix that. Other builders don't seem to have had this problem. I'm a step away from thinking my kit - which was the first to be sold in the UK - has some incorrect part(s) supplied, or a manufacturing defect, but I want to try to cover all bases first before I go back to Tecnam in Italy. Tecnam UK has taken several forms since I first purchased the kit in 2005
Correct assembly has been verified, I just can't seem to adjust the pushrods and turnbuckles to sort this out! Thanks again
Last edited by billythefrog; 8th Nov 2023 at 21:48. Reason: Removal of HTML tags
Moderator
As there is a certified version of the airplane, you can be pretty confident that the intended control deflection for your non certified one, will be very similar, or the same as the certified one. The maintenance manual for the certified one must give travel range and rigging instructions. That's your starting point.
In general, aileron travel will be limited to around 20 some degrees in the greater travel direction, and may be less to none in the opposite direction (Tiger Moth). A travel range exceeding 30 degrees would be aerodynamically very unusual. For reference, in Canada, flap extension angles on amateur built airplanes is not permitted to exceed 40 degrees. So if you're anywhere near that, you're way away from where you should be.
For sure, ask questions. too much aileron travel, and an aerodynamically stalled aileron will make for a very unpleasant to fly airplane!
In general, aileron travel will be limited to around 20 some degrees in the greater travel direction, and may be less to none in the opposite direction (Tiger Moth). A travel range exceeding 30 degrees would be aerodynamically very unusual. For reference, in Canada, flap extension angles on amateur built airplanes is not permitted to exceed 40 degrees. So if you're anywhere near that, you're way away from where you should be.
For sure, ask questions. too much aileron travel, and an aerodynamically stalled aileron will make for a very unpleasant to fly airplane!
If the maintenance manual does not provide rigging instructions, you could contact Tecnam for clarification of the procedure as it is something they should be able to provide. Sycamore's description is a good starting point, but the factory should be able to supply more detailed instructions. Something else I was thinking of: do you have a maintenance organisation nearby, preferably one with experience of dealing with Tecnam types? A friendly chat with someone there might also be useful for you.
You say that the movement is a certain percentage too much. So you must have measured the degrees of actuation, and then done a calculation.
I would think the the push rods and bell cranks are just a way of getting the movement from the column to the ailerons. What you should be looking for is where are the column stops, and can they be adjusted. On most aircraft the neutral position results in about a 3 degree droop of both ailerons, which goes to zero when subjected to some airflow. The geometry of the bell cranks will give more upward movement than downward movement, to reduce any adverse yaw.
I would think the the push rods and bell cranks are just a way of getting the movement from the column to the ailerons. What you should be looking for is where are the column stops, and can they be adjusted. On most aircraft the neutral position results in about a 3 degree droop of both ailerons, which goes to zero when subjected to some airflow. The geometry of the bell cranks will give more upward movement than downward movement, to reduce any adverse yaw.
Moderator
On most aircraft the neutral position results in about a 3 degree droop of both ailerons, which goes to zero when subjected to some airflow.
Billy,
I must confess that your post leaves me somewhat concerned. As a retired licensed engineer (mainly GA), my last employer was a Part-145 organisation responsible for maintenance on several examples of the 2002, although I was never personally very involved in its maintenance and can't speak from direct experience. Our Tecnams were not highly regarded by my colleagues, particularly in terms of build-quality (which should not affect your example), but I believe it is well designed to conventional airworthiness criteria. I am surprise by your absence of rigging data, either in the form of a maintenance manual or assembly process sheets. You have a kit, but no instructions? Some points to consider;
1. Almost no aeroplane has its flying control range-of-movement determined by how far you can move the stick. Each aileron should have "primary" stop, in the form of an adjustable-length bolt, normally acting on each aileron's input bellcrank, and limiting the movement of the aileron (whether it is attached to the rest of the control-system or not).
2. There should be a "secondary" stop adjacent to the control stick. The purpose of the secondary stop is, on a completely rigged system, to limit the amount of tension/compression that can be applied to the system when the ailerons are at full travel, to prevent overstressing the control system. When the stick is moved gently to the limits of travel (ie, when the primary-stops make contact) there should be a small gap at the secondary stops, which can be closed by further pressure on the stick.
3. The system must always be rigged initially with all its contituent parts in "neutral". There should be a means of securing the stick in neutral, perhaps a rigging pin or clamp. The ailerons should normally be placed in neutral by aligning with the T/E of the wing. This is important; the bellcranks should also be secured in neutral. It is not sufficient that the stick-and-aileron are neutral if the bellcranks are at weird angles, as this will give a non-linear nmovement of the aileron in response to movement of the stick.
4. With all the components in neutral, prepare the pushrods by screwing each rose bearing in equally. Install the pushrods by adjusting the rose bearings equally until the attachment bolts slide in freely. There should be a defined means of ensuring that the rose-bearings have sufficient threads engaged.
5. Install the cables and turnbuckles, tighten the turnbuckles to take up the slack whilst ensuring that the stick and bellcranks remain in neutral. Tighten the turnbuckles further (equally) to achieve the specified tension.
6. Remove all your rigging pins and clamps. Ensure that the controls move freely, in the appropriate direction, and to the correct range.
7. Absolutely vital;
a. make sure that you've removed all your tooling.
b. make sure that the controls move in the right direction.
c. make sure that all threads are sufficiently engaged.
d. make sure that all locking devices/safety-wire are installed and secure.
e. make sure that a competent person performs a duplicate inspection of b. to d.
f. check again that the controls movie in the right direction!
8. Although you've only asked about an aileron problem, everything applies to the other control systems as well.
I must confess that your post leaves me somewhat concerned. As a retired licensed engineer (mainly GA), my last employer was a Part-145 organisation responsible for maintenance on several examples of the 2002, although I was never personally very involved in its maintenance and can't speak from direct experience. Our Tecnams were not highly regarded by my colleagues, particularly in terms of build-quality (which should not affect your example), but I believe it is well designed to conventional airworthiness criteria. I am surprise by your absence of rigging data, either in the form of a maintenance manual or assembly process sheets. You have a kit, but no instructions? Some points to consider;
1. Almost no aeroplane has its flying control range-of-movement determined by how far you can move the stick. Each aileron should have "primary" stop, in the form of an adjustable-length bolt, normally acting on each aileron's input bellcrank, and limiting the movement of the aileron (whether it is attached to the rest of the control-system or not).
2. There should be a "secondary" stop adjacent to the control stick. The purpose of the secondary stop is, on a completely rigged system, to limit the amount of tension/compression that can be applied to the system when the ailerons are at full travel, to prevent overstressing the control system. When the stick is moved gently to the limits of travel (ie, when the primary-stops make contact) there should be a small gap at the secondary stops, which can be closed by further pressure on the stick.
3. The system must always be rigged initially with all its contituent parts in "neutral". There should be a means of securing the stick in neutral, perhaps a rigging pin or clamp. The ailerons should normally be placed in neutral by aligning with the T/E of the wing. This is important; the bellcranks should also be secured in neutral. It is not sufficient that the stick-and-aileron are neutral if the bellcranks are at weird angles, as this will give a non-linear nmovement of the aileron in response to movement of the stick.
4. With all the components in neutral, prepare the pushrods by screwing each rose bearing in equally. Install the pushrods by adjusting the rose bearings equally until the attachment bolts slide in freely. There should be a defined means of ensuring that the rose-bearings have sufficient threads engaged.
5. Install the cables and turnbuckles, tighten the turnbuckles to take up the slack whilst ensuring that the stick and bellcranks remain in neutral. Tighten the turnbuckles further (equally) to achieve the specified tension.
6. Remove all your rigging pins and clamps. Ensure that the controls move freely, in the appropriate direction, and to the correct range.
7. Absolutely vital;
a. make sure that you've removed all your tooling.
b. make sure that the controls move in the right direction.
c. make sure that all threads are sufficiently engaged.
d. make sure that all locking devices/safety-wire are installed and secure.
e. make sure that a competent person performs a duplicate inspection of b. to d.
f. check again that the controls movie in the right direction!
8. Although you've only asked about an aileron problem, everything applies to the other control systems as well.
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Moderator
e. make sure that a competent person performs a duplicate inspection of b. to d.
The one (a Cessna 206) had a very difficult to detect, but rather critical rigging error. I check it myself, and did not see it the first time either. When the mechanic told me he had corrected it, I insisted that he accompany me on the next test flight. He resisted, I insisted. It still wasn't right, once in the air, he then agreed with me! Eight hours later, it was correctly rigged, and flew properly!
Thread Starter
Thanks all - I do have aileron deflection ranges specified for both the certified and homebuild versions, they're identical (+20 to -15) but with marginal differences in tolerance. No rigging instructions were supplied, so thank you all for the tips.
The problem I have is limiting travel - my range is too great and there are no travel stops in the (aileron control system) design - either primary (at the bellcrank in the wing) or secondary (at the yoke). At this point I may have to engineer this; what I'd really like is to understand why this would be necessary, i.e. root cause.
Echo Pilot DAR 's point about flap deflection - on this type, the UK (LAA) homebuilt specs have actually reduced flap deflection from 40 degrees (on the certified version) to 33 degrees (on the homebuilt) to prevent an observed unpleasant wing drop on stall at high AoAs.
The problem I have is limiting travel - my range is too great and there are no travel stops in the (aileron control system) design - either primary (at the bellcrank in the wing) or secondary (at the yoke). At this point I may have to engineer this; what I'd really like is to understand why this would be necessary, i.e. root cause.
Echo Pilot DAR 's point about flap deflection - on this type, the UK (LAA) homebuilt specs have actually reduced flap deflection from 40 degrees (on the certified version) to 33 degrees (on the homebuilt) to prevent an observed unpleasant wing drop on stall at high AoAs.
Last edited by billythefrog; 13th Nov 2023 at 09:08.
the UK (LAA) homebuilt specs have actually reduced flap deflection from 40 degrees (on the certified version) to 33 degrees (on the homebuilt)
Thread Starter
Yes. Also the flap extension reduction is a Mandatory Permit Directive, with fairly clear instructions! Thanks
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Thread Starter
Yes, I have the Illustrated Parts Catalogue, the plans for the aircraft - there are no control stops in the aileron system so the only rational explanation is that aileron travel is down to the travel of the yoke / control stick. There are primary stops in the *elevator* (actually a stabilator) fitted at the factory, and given that the flap is electrically operated, there is a microswitch within the actuator / servo which is moved to limit the travel of the flap... but nothing on the aileron control system, or rudder control system!
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Yes, I have the Illustrated Parts Catalogue, the plans for the aircraft - there are no control stops in the aileron system so the only rational explanation is that aileron travel is down to the travel of the yoke / control stick. There are primary stops in the *elevator* (actually a stabilator) fitted at the factory, and given that the flap is electrically operated, there is a microswitch within the actuator / servo which is moved to limit the travel of the flap... but nothing on the aileron control system, or rudder control system!
You seem to have a problem of excessive range. Adjusting rods wont fix that.
Is there somewhere where a radial motion is imparted into the system?
A little difficult to explain however.
Think of a bar that rotates about a fixed point at one end. If you attach an output at the opposite end for every degree of rotation it will impart a linear output.
If you move the output to a position halfway along the bar you will reduce the linear output for the same angular motion.
Thereby you have reduced the total range. Then the range can be "positioned" by a rod adjustment.
This type of adjustment is used on a number of helicopters for engine controls.
Thread Starter
Billy,
I must confess that your post leaves me somewhat concerned. As a retired licensed engineer (mainly GA), my last employer was a Part-145 organisation responsible for maintenance on several examples of the 2002, although I was never personally very involved in its maintenance and can't speak from direct experience. Our Tecnams were not highly regarded by my colleagues, particularly in terms of build-quality (which should not affect your example), but I believe it is well designed to conventional airworthiness criteria. I am surprise by your absence of rigging data, either in the form of a maintenance manual or assembly process sheets. You have a kit, but no instructions? Some points to consider;
1. Almost no aeroplane has its flying control range-of-movement determined by how far you can move the stick. Each aileron should have "primary" stop, in the form of an adjustable-length bolt, normally acting on each aileron's input bellcrank, and limiting the movement of the aileron (whether it is attached to the rest of the control-system or not).
2. There should be a "secondary" stop adjacent to the control stick. The purpose of the secondary stop is, on a completely rigged system, to limit the amount of tension/compression that can be applied to the system when the ailerons are at full travel, to prevent overstressing the control system. When the stick is moved gently to the limits of travel (ie, when the primary-stops make contact) there should be a small gap at the secondary stops, which can be closed by further pressure on the stick.
3. The system must always be rigged initially with all its contituent parts in "neutral". There should be a means of securing the stick in neutral, perhaps a rigging pin or clamp. The ailerons should normally be placed in neutral by aligning with the T/E of the wing. This is important; the bellcranks should also be secured in neutral. It is not sufficient that the stick-and-aileron are neutral if the bellcranks are at weird angles, as this will give a non-linear nmovement of the aileron in response to movement of the stick.
4. With all the components in neutral, prepare the pushrods by screwing each rose bearing in equally. Install the pushrods by adjusting the rose bearings equally until the attachment bolts slide in freely. There should be a defined means of ensuring that the rose-bearings have sufficient threads engaged.
5. Install the cables and turnbuckles, tighten the turnbuckles to take up the slack whilst ensuring that the stick and bellcranks remain in neutral. Tighten the turnbuckles further (equally) to achieve the specified tension.
6. Remove all your rigging pins and clamps. Ensure that the controls move freely, in the appropriate direction, and to the correct range.
7. Absolutely vital;
a. make sure that you've removed all your tooling.
b. make sure that the controls move in the right direction.
c. make sure that all threads are sufficiently engaged.
d. make sure that all locking devices/safety-wire are installed and secure.
e. make sure that a competent person performs a duplicate inspection of b. to d.
f. check again that the controls movie in the right direction!
8. Although you've only asked about an aileron problem, everything applies to the other control systems as well.
I must confess that your post leaves me somewhat concerned. As a retired licensed engineer (mainly GA), my last employer was a Part-145 organisation responsible for maintenance on several examples of the 2002, although I was never personally very involved in its maintenance and can't speak from direct experience. Our Tecnams were not highly regarded by my colleagues, particularly in terms of build-quality (which should not affect your example), but I believe it is well designed to conventional airworthiness criteria. I am surprise by your absence of rigging data, either in the form of a maintenance manual or assembly process sheets. You have a kit, but no instructions? Some points to consider;
1. Almost no aeroplane has its flying control range-of-movement determined by how far you can move the stick. Each aileron should have "primary" stop, in the form of an adjustable-length bolt, normally acting on each aileron's input bellcrank, and limiting the movement of the aileron (whether it is attached to the rest of the control-system or not).
2. There should be a "secondary" stop adjacent to the control stick. The purpose of the secondary stop is, on a completely rigged system, to limit the amount of tension/compression that can be applied to the system when the ailerons are at full travel, to prevent overstressing the control system. When the stick is moved gently to the limits of travel (ie, when the primary-stops make contact) there should be a small gap at the secondary stops, which can be closed by further pressure on the stick.
3. The system must always be rigged initially with all its contituent parts in "neutral". There should be a means of securing the stick in neutral, perhaps a rigging pin or clamp. The ailerons should normally be placed in neutral by aligning with the T/E of the wing. This is important; the bellcranks should also be secured in neutral. It is not sufficient that the stick-and-aileron are neutral if the bellcranks are at weird angles, as this will give a non-linear nmovement of the aileron in response to movement of the stick.
4. With all the components in neutral, prepare the pushrods by screwing each rose bearing in equally. Install the pushrods by adjusting the rose bearings equally until the attachment bolts slide in freely. There should be a defined means of ensuring that the rose-bearings have sufficient threads engaged.
5. Install the cables and turnbuckles, tighten the turnbuckles to take up the slack whilst ensuring that the stick and bellcranks remain in neutral. Tighten the turnbuckles further (equally) to achieve the specified tension.
6. Remove all your rigging pins and clamps. Ensure that the controls move freely, in the appropriate direction, and to the correct range.
7. Absolutely vital;
a. make sure that you've removed all your tooling.
b. make sure that the controls move in the right direction.
c. make sure that all threads are sufficiently engaged.
d. make sure that all locking devices/safety-wire are installed and secure.
e. make sure that a competent person performs a duplicate inspection of b. to d.
f. check again that the controls movie in the right direction!
8. Although you've only asked about an aileron problem, everything applies to the other control systems as well.
Thanks Duncan. There are no stops in the design. I have the aileron and flap clamped both sides and the stick is clamped vertical with a sprit level (the a/c is also lat/long levelled). Agree with rigging a neutral setup but I'm not 100% what 'neutral' looks like at the bellcrank - I assume it would be the position where the wing pushrods (to the bellcrank from the yoke) exert the maximum movement of the bellcrank in both directions - in other words, the bellcrank arm is perpendicular to the wing pushrod where they connect at a rose joint? I need to call Tecnam again for advice but I can't say that their support has been exemplary
Or rather too much output for the same angular rotation.
Thread Starter
Thanks ericferret
Yes, I thought of that too but the construction matches that in the design (this has been checked by my LAA inspector)... And, besides, the wing pushrod wouldn't fit through the corresponding holes in the wing ribs if it were in the wrong place!
Yes, I thought of that too but the construction matches that in the design (this has been checked by my LAA inspector)... And, besides, the wing pushrod wouldn't fit through the corresponding holes in the wing ribs if it were in the wrong place!