Aileron alignment question

[Magman]

It is possible, they are right. Asked to see the rigging fixtures to see what they used. If they cannot produce them, they are wrong.
The “I/a/w” really isn’t .

 

[murphey]

Yeah, they have a massive library of maintenance manuals... Plus they own and operate their own Arrow 2.

Great! Next question - do they ever open the manuals, read them and use the info?

 

[Dan Thomas]

Also, I should add they reserved the right to change their mind based on what they see in person tomorrow.

They need to change their minds based on what the Service Manual says. What they see might look right to them if they're not in the habit of consulting the manual.

There is a common "norm" in aircraft maintenance: Doing stuff the way you picked it up in your apprenticeship, or just flying in the dark and coming up with your own methods. But if your own methods don't match with the service manuals, you're not going to get it right.

Norms are one of the Dirty Dozen Human Factors in aircraft maintenance. They lead to mistakes.



As always, there is overlap, and there are at least two of these at work in the flap and aileron problems. Norms cause mechanics to do the procedure the wrong way. Maybe the manual isn't available, so we have the Lack of Resources. That in turn causes a Lack of Knowledge. Maybe the mechanic know that he should have the manual but the boss won't buy them, so the mechanic suffers a Lack of Assertiveness when he knuckles under and just makes adjustments instead of refusing to shortcut the work like that. If the boss isn't supporting his staff, we have a Lack of Teamwork.

 

[ArrowFlyer86]

They need to change their minds based on what the Service Manual says. What they see might look right to them if they're not in the habit of consulting the manual.

Thanks.

I'm going to flip open the mx manual and point to the steps about aileron rigging and then ask them to do what's outlined. But at the end of the day it's up to them to actually follow through with each step.
And like most customers I'll be none the wiser if they take a short-cut. I'll have to take their word that it was done right.

Re: human factors. That I can't control.
Also, IMHO, that list is missing one: work ethic. If you don't have that internal drive and pride in your work then no exogenous factors about the situation is going to improve the outcome*.
EDIT: *Unless someone has a gun to your head and makes you do the right steps, then I think that would overpower poor work ethic

 

[jsstevens]

If you don’t tell her you’ll have lots more free time.

For a while, maybe...

 

[Magman]

You need 2 small fixtures to position bellcranks when adjusting cables.

Then you need a fixture to check aileron position when adjusting pushrods.

These are 2 separate procedures. You do not adjust cables to line up

ailerons. Doing so without centering bellcranks will result in the travel of

left and right being different.


An aileron deflected downward has more drag than when deflected upward

the same amount. Most modern aircraft have the aileron move upward

more than the opposite one moves down. Along with other features

this is helpful in maintaining coordinated by reducing Adverse Yaw.

Adverse Yaw is having more drag on the wing opposite the desired turn.

ie Turning LEFT but yawing RIGHT.

Poor rigging can make a good pilot look bad!

 

[Dan Thomas]

And like most customers I'll be none the wiser if they take a short-cut. I'll have to take their word that it was done right.

Oh, you can tell. If the ailerons are lined up with the flaps, good. (As long as the flap rigging was done right!) If you move each aileron up and down by hand, you should feel its bellcrank contact the stops at the ends of the travel. If the bellcranks are off, and the cables have been adjusted to get the ailerons streamlined, the bellcrank will only contact the top OR the bottom stop, on both ailerons. Now the travels are limited and the differentials screwed up.

This is why manuals were published. Lots of moving parts that have to be coordinated properly. In the old days, when cables ran directly to the ailerons, cable adjustment was all you could do.

 

[Magman]

Low cable tension can give lower actual travel in flight due to air loads.

Sort of like driving with low tire pressures.