ASSEMBLY MANUAL XAIR 2009, May, 20
©Randkar 2009
Prohibited reproduction
/ Reproduction interdite MANUEL DE MONTAGE XAIR 20 Mai 2009
Page 68 / 86
H/ FINAL TUNING OF CONTROLS AND CONTROL SUR-
FACES.
This stage is all too often neglected. Yet, these adjustments make all the difference between an
aircraft that gives smooth, coherent response, and a cantankerous, even dangerous beast.
1) The elevator:
Make sure the pivot bolts are not too tight against the washers.
A very important point: adjusting the trim shock cord: attach the shock cord on the main
elevator tube approximately 50cm behind the seats with the ring clip supplied. Attach the
other end at the point where all fuselage tubes meet, next to the stainless steel plate, around
the cup washer. This shock cord is to compensate the weight of the elevator. It should be
tensioned just enough so that the elevator does not drop when released. This should be
checked regularly, say every 25 hours, or the aircraft will develop nose-down tendency as
the rubber ages. Also, it is cheap enough to replace at every 100 hour inspection.
Elevator trim tab: first of all, check it responds in the right direction! Push the trim lever
forward: the tab should move up (so as to push the elevator down, for a nose down re-
sponse).
Second, adjust the cables so that
the trim tab is in line with the elevator when the lever
is vertical.
The trim cables must be tight, but don’t go to excess; number of turns wrapped
on the pulley: 2 1/2. Do not apply any lubricant: here, the more friction, the better! You also
need a small screw to stop the cable from slipping.
2) The ailerons:
Check that the ailerons have been setted as explain in chapter F3
3) The rudder:
First of all, and once again, because this bears repeating, make sure that:
THE RUDDER CABLES ARE CROSSED!!
The cables will be under slight tension when the rudder is centered; slack in all other posi-
tions is normal. To eliminate any possibility of the cables jamming over the bolt that ties
the two rear support tubes, next to the stainless plate, it is a good idea to make two simple
leads using plastic ties and pieces of gas hose, tied to the leading edge of the stabilizer.
(D7A)
When the pedals are lined up, the rudder should be in line with the longitudinal axis of the
aircraft: the easiest way to get this is to clamp the rudder between two cleats and set the ad-
justable links so that:
- the nose wheel is in line with the longitudinal axis
- the pedals are lined up
- the cables are slightly taut
Watch out those pulleys! The pulleys at the after end of the keel must be installed so that
they cannot move off of their bearings: the red mark must be visible from outside, (only
this way will the bearing keep the pulley in place).
4) Rudder tab
(N°146) it corrects engine torque effects. Mount it after the first trial
flights if necessary.
H4