Aileron Rigging

[WorkingHard]

I am a pilot not an engineer so please allow the intrusion into this forum. I recently saw a Cessna 172 where the ailerons were rigged so that in the level position they appeared to have a slight "droop". I have seen other aircraft where the ailerons appear to have a slight “uplift” but not the other way. Would there be a reason for the droop and how in general terms would you expect to see the rigging of ailerons?
Hope I have made this clear enough.

[SRTDub]

Hey, i will try my best to answer this query for you, I am actually qquite surprised that you have seen aircraft with the ailerons rigged slightly upwards, the normal procedure is to rig them neutral, but occasi9onally some aircraft call for them to be rigged with a 1/2 inch droop from the mainplane, this in my opinion is to created a tad more lift(Big aircraft A330 for instance have hydraulic aileron droop whih allows ailerons to droop a little when neutral to provide more lift!) or it could be to counter-act adverse yaw, or possibly to pick up any slack in the controls, but i dont think i have personally ever seen aan aircraft with ailerons rigged upwards!, Hope this helps!!

[muduckace]

I now nothing of the bug smashers, The MD-11 has a configurable option for deflected ailerons (droop) to add lift for rwy T/O performance. I believe they deflect at flaps 15 and clean up with the rest of the wing.

[CONSPICUITY]

Hi On the A320 the ailerons are deflected downwards when the flaps are extended to follow the wing contour also the droop function also increases lift on the part of the wing which is not equipped by flaps.

[mitzy69]

both ailerons rigged down on the ground, could be that in flight they will be level as the air loads push both ailerons up. due to the cables stretching or backlash being taken up in control runs.

[Von Klinkerhoffen]

Mitzy69 is correct , it allows for aileron upfloat due to cable stretch under aero loads . Quite a few cable controlled aircraft , all the way up to some business jets , have this feature !

VK

[jimpy1979uk]

On the 747 the outboard ailerons are rigged about an inch downwards and the inboard ailerons are rigged in the neutral position.

[SNS3Guppy]

I don't know off hand about the 172, but the last ailerons I rigged were on a 182...and they both were rigged down per the mx manual.

I was re-rigging to correct for the previous work done...which had rigged them neutral, with the control yoke nearly 90 degrees to the right. The airplane couldn't turn right in flight. When I inquired with the previous individual, who had done the work, he told me it was fine, and that it just needed a little rudder input...

[WorkingHard]

Thanks folks, interesting replies so far especially SNS3Guppy. As a matter of interest I think if my control systems had so much slack as suggested I would ish to have all control linkages checked or am I being over cautious?

[Rigga]

I last messed about with them in the mid 80's.
I seem to remember that the whole aileron system wasnt as tight as you'd expect anyway.
Although we'd set them up to the book some owners liked them adjusted down a bit - as is said "adds a bit of lift" - at lower speeds I'd assume. As long as it was recorded in the Log Book this was acceptable (then). Dont know what the rules would say now?

[Germstone]

iirc C172 ailerons are rigged neutral against the flaps in the up position any aileron droop could be due to a loose carry through cable or just a badly rigged system.

I think the C152 is rigged .5degree droop on the ailerons

[SNS3Guppy]

As a matter of interest I think if my control systems had so much slack as suggested I would ish to have all control linkages checked or am I being over cautious

Slack probably needs to be defined a little more. What one interprets in the cockpit as "slack" can mean a lot of things. If it's play between the control yokes, there's not a lot that can be done, within certain limits. If it's play between the control in the cockpit and the control surface on the wing or stabs, then it's a big concern.

Taking up "slack" is a lot more than checking linkages. It's checking cables, turnbuckles, pulleys, bellcranks, and particularly cable tensions, as well as overall rigging.

You will notice a certain amount of play in rod ends and other points in the system, which can only be removed by replacing those components. A certain amount of play is acceptable, but not much.

You're not being overly cautious. If you have any concerns at all, you should have it checked over by a qualified mechanic.

Although we'd set them up to the book some owners liked them adjusted down a bit - as is said "adds a bit of lift" - at lower speeds I'd assume. As long as it was recorded in the Log Book this was acceptable (then).


Control rigging is a critical issue, and the rule now, as it has always been, is that it must be done in accordance with the manufacturer specifications or as ammended (eg, supplemental type certificate, etc).

An old mechanic's trick for an airplane out of trim laterally is to rig a flap low to "pick up" the wing. This is really poor practice for addressing the symptoms, and not the problem.

[Malcom]

HP Victor had ailerons rigged up a bit - design related to address fatigue issues.


An old mechanic's trick for an airplane out of trim laterally is to rig a flap low to "pick up" the wing. This is really poor practice for addressing the symptoms, and not the problem.

Quote from the PA-28 Maintenance Manual:
In the event of wing heaviness during flight, the flap on the side of the heavy wing can be adjusted down from neutral to remedy this condition by lengthening the control rod. Check the inspection hole in each rod end to ascertain that there are sufficient threads remaining and a wire cannot be inserted through these holes. Rod ends without check holes, maintain a minimum of .375 of an inch thread engagement. Do not raise the flap of the other wing above neutral.

Glad I dont fly one of them - what were they thinking!:rolleyes:

[blackhand]

...... from the PA-28 Maintenance Manual:
In the event of wing heaviness during flight, the flap on the side of the heavy wing can be adjusted down from neutral to remedy this condition
Nomad N22 and N24 series is the same.

This is a common rectification for light aircraft.

Cheers
Blackhand

[172_driver]

Is that asymmetrical rigging possible on a C172 with its electrical flaps?
Just curious, a few of the C172:s I fly feel like they definitely prefer right turns over left (or the opposite)...

[Germstone]

Is that asymmetrical rigging possible on a C172 with its electrical flaps?
Just curious, a few of the C172:s I fly feel like they definitely prefer right turns over left (or the opposite)...


yes possible by adjustment of the eye ends at the flap and at the flap bellcrank ends

[Von Klinkerhoffen]

yes possible by adjustment of the eye ends at the flap and at the flap bellcrank ends


Its been a while for me but............ not legal I think . Definately for the 150/152 and I think also for the 172,182,etc, to correct a wing heavy condition the wing root trailing edge is adjusted up or down via an eccentric bush at the rear spar attachment bolt ! The flaps must stay rigged neutral .

VK

[Gargleblaster]

Some aircraft have what I think is called "flaperons", combined flaps and ailerons. Mostly used on sailplanes I think.

[Germstone]

Quote:
yes possible by adjustment of the eye ends at the flap and at the flap bellcrank ends

Its been a while for me but............ not legal I think . Definately for the 150/152 and I think also for the 172,182,etc, to correct a wing heavy condition the wing root trailing edge is adjusted up or down via an eccentric bush at the rear spar attachment bolt ! The flaps must stay rigged neutral .

VK

VK

It was asked if it was possible to rig the the flaps asymmetrically not if it was the correct way to cure a heavy wing ;-)