mun_iz

Hi,

Facing a problem with a sticky main retract. It will not extend. However, a slight nudge/press on the main oleo causes it to snap and extend....

I remember reading about this problem long ago somewhere in this forum. If I do not remember wrongly, the problem is caused by the locking mechanism (slot) on the side plates of the retract units with the angle of the slot being too sharp. The solution was to file the angle to a radius.

But before I start filing away, can someone advise on the possible problem and solution?

Any input will be greatly appreciated.

Thanks.

Isaac

[youtube]http://www.youtube.com/watch?v=NLYWUZiHCCQ[/youtube]

BaldEagel

Issac

Can't see the vid its denoted as private.

Mike

k12rc

Same here said private picrure

mun_iz

Sorry about the hiccup... I had set it to public... please try again. Thanks

k12rc

is the wheel hitting the top wing skin if so try shimming it down

lov2flyrc

My Feedback: (24)

Looks like something may be hitting in the retracted position causing it to hang in the lock. Make sure the wheel (or strut) is not hitting the skin (top skin too). Another thing to check is loosening the mounting screws slightly and cycle the gear to confirm you are not tweaking the frames out of square with uneven mounting rails.
If neither of these reveal the issue, remove the retract and move the slide bar manually by hand to check the section of slide rail where the retracted lock area is for any tightness or burrs in the slide channel.

mun_iz

Hi all,

Thanks for the suggestions. It is not an issue of the wheel or oleo binding in that there is ample clearance between the oleos, wheels and the hole on the fuselage.

But I will check flatness of the mounting rails, as well as, the slide channel tonight.

alasdair

I had a sticky main gear on a CARF Lightning.
It turned out to be a piece of very thin wire jamming between the leg and the frame when retracted. The wire was there to hold the brake air tube in place, and the builder had filed a tiny notch in the leg for the wire. But when the wire slipped out of the notch it restricted the leg clearance.
It takes so little to cause a restriction, and it can be so hard to find.

EagleJC

My Feedback: (2)

Also, you can try to add some gear oil to retract area due to winter cold weather.

cyphur01

I agree with Todd. Number one cause of locking in up position is the rail is tweaked causing the retract to bend and one lock releasing before the other. . Take the retract out of the airframe, tighten all of the screws holding the frame together. Check operation outside making sure the locks are disengaging simultaneously. Then reinstall in airframe. Tighten down. If it still sticks, loosen one screw at a time. If loosening a certain screw makes the locks release, place a washer under this screw against the mounting rails to even out the retract. I have had to do this to a couple of arfs with rails that are not quite in alignment.

Rush!

+1 havnt had any issues with AP retract unit... probably an uneven mounting rail.

mun_iz

Hi all,

Thank you for the suggestions. I had not done any corrective work on the retract yet but I did managed to do some further tests and this is what I had discovered.

When the airtank is filled up to 8 bars, the sticky problem surfaces. When the pressure drops to 3 bars when I cycle the retracts continuously, the problem goes away and the retracts work perfect.... now I am baffled. I tested a few times and got the same results. Seems like it works well at 3 bar pressure but if I fill up to 3 bars, I wont have enough pressure /air in the tank to cycle the retracts twice.

The retract frame are sitting firmly and flat on the rails and inspecting it visually, I cant find any high spots or uneveness that would probably had caused tweaking of the frames.

I think I will remove the retract later and check for tightness in the slide rails at the area where it locks the slide bar in the up position.


I will post another video later to show this prob.