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H/ FINAL TUNING OF CONTROLS AND CONTROL SURFACES.
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 re-
place 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 response).
Second, adjust the cables so that the trim tab is in line with the elevator when the lever is verti-
cal. The trim cables must be tight, but don't go to excess; number of turns wrapped on the pulley:
three. 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:
-Get two straight tubes or rulers, about 2m (6ft) long. Two helpers will make things easier.
-The turnbuckles must be adjusted so that:
The aileron tips are flush with the two rulers held tight against the leading
edge and trailing edge, lying parallel to the keel, level with the inboard, wider ends of the ailerons.
(Caution: if you place the rulers elsewhere along the wing, aileron angle will be set differently due to
wing twist).
Both control sticks in vertical position.
NOTE: It is not a good idea to have the cables too tight; a reasonable amount of play is preferable, so
that the ailerons are not too « stiff », due to excessive friction.
When you are satisfied, do not forget to safety wire the turnbuckles.
Also check that the sticks do not bind on the pitch axis: the bolts must be free.
R A N D K A R s . a . A S S E M B L Y M A N U A L X A I R 2 0 0 6 , J u n e , 0 4
M A N U E L D E M O N T A G E X A I R 0 4 J u i n 2 0 0 6
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 positions is nor-
mal. 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 adjustable 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 neces-
sary
.
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