Rans S-12, Руководство по эксплуатации для пилотов

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Chapter 5 - Airframe Maintenance
Overview
MAINTENANCE OF THIS AIRCRAFT CAN BE CARRIED OUT BY NEARLY
ANYONE, HOWEVER A REQUIRED “CONDITION INSPECTION” EVERY 12
MONTHS CAN ONLY BE PERFORMED BY THE HOLDER OF THE REPAIR-
MAN’S CERTIFICATE FOR THIS AIRCRAFT (N6167U) OR A LICENSED A&P
MECHANIC.
This condition inspection is carried out in much the same manner as an “annual” that produc-
tion airplane owners are used to. Certificated parts, such as a certified engine, or other parts
certified for use on an airplane automatically are designated as unapproved when installed and
operated on an amateur-build aircraft. For this very reason, airworthiness directives do not
legally apply to this aircraft unless the directive specifically cites N6167U as non-compliant.
These technicalities notwithstanding, it would likely be foolish to disregard a factory AD on
any component of the aircraft. The safety of this aircraft rests primarily on the owner/operator
and designated repairman, not the FAA and not the engine or airframe manufacturer. Use com-
mon sense and show respect for the aircraft.
It is recommended to conduct an inspection which is the equal of a condition inspection, at 100
hour intervals. Of course when performed for a 100 hour interval purpose, the inspection does
not need to be carried out by the designated repairman.
As the reader might expect, this listing of maintenance is not comprehensive. Refer to records
kept in the aircraft logbook for additional practicle maintenance information. In most cases if
something requires periodic maintenance, the mechanic will make a meaningful entry in the
logbook reflecting what he/she has discovered.
Builder Key Areas
The pulley mount behind the left seat for the aileron cable was not manufactured properly and
may allow the pulley to ‘cam over’ into a non-free state whereby friction and control integrity
are severely compromised. As an effort to reduce the magnitude of this effect, the hoop was
bent slightly. This hoop should be inspected after the first hour, then doubling the interval until
it reaches the 100 hour point at which it is included in every 100 hour inspection.
The nut plates for the 3/16” bolts retaining the tail boom were noticed to behave in an unfa-
miliar fashion, due primarily with the builders inexperience with such fragile hardware and as
a result all 3/16” AN hardware used to mount the tailboom to the main fuselage cage should
be inspected at 5 hour intervals until the first 100 hours at which time they will be included in
every 100 hour inspection.
The mounting points for the control stick were slightly misaligned due in part to to an error
by the kit manufacturer and as a result the control stick may exhibit binding or galling when
moved fore and aft (elevator). The control stick (primarily elevator control movement) should
be inspected at 5 hours then every 25 until the 100 hour point at which time it remains on the
100 hour inspection list. This included the collar at the foremost part of the tail boom where
the elevator control rod passes thru to connect to the push-pull tube. This collar should be
lubricated with anti-seize at intervals of 25 hours or 1 year.
The manufacturer’s design of the rudder pedal and brake system (including the floor panel to
which it is mounted) is such that a great deal of stress is placed on key hardware. The bolts
used to secure the rudder assembly to the floor pan produce undue force and may eventually
cause failure of the mounting tabs or other associated hardware. This entire sub-system should
be inspected (under load) to ensure it’s integrity at 25 hour until reaching the 100 hour mark at
which time it will remain on the 100 hour inspection list.
The lower strut attach points were necessarily modified when it was discovered the
OEM equipment provided for less than 6 threads of engagement. The blocks into which the
ball joint for the rear strut lower attach point engages were manufactured to new specifications
from 4130 material and such that over 20 threads were engaged. The threads in this block
were NOT roll formed but instead cut and as a result must be inspected closely. This inspec-
tion necessitates removal of the bolt thru the rod end (and subsequent replacement of the lock
nut after 3 uses) and will remain on the 100 hour inspection list.
The jury struts don’t fit too great and have a lot of slop where the pins attach them to the main
struts. As a result of this mis-fit, it is anticipated that there will be some play and movement
in the system. At 10 hours then every 25 hours the safety wire should be cut, the pins removed
and the pins and holes inspected for wear until reaching the 100 hour mark at which time it
will remain on the 100 hour inspection list.
Periodic Inspection Points (100hr, Condition Insp., etc.)
Most items of inspection that are listed in the condition inspection checklist in Appendix E
should be included in the 100 hour inspections. In some respects this is unjustified but because
this aircraft is not built overly strong and because of the nature of the kit-build process, it is
wise to inspect everything closely after 100 hours, afterall that amounts to about 6,500 miles.
The wing struts should be inspected thoroughly (spend 15 minutes) every 10 hours. This
includes all bolts, safety wire, cotter pins etc. The struts, because they are extruded aluminum,
are particularly sensitive to nicks, dings and scratches. Look carefully for sings of wear par-
ticularly at the ends of the struts where hardware is mounted. The integrity of the jury struts is
also critical because failure of a jury strut could very quickly and violently lead to buckling of
a main strut. The plates and mounts to which the struts bolt on the wings and on the fuselage
are equally as important. Failure of the pin at the lower strut attach point, for example, would
lead to immediate loss of one wing and departure from controlled flight (serious injury or death
would follow). Likewise the integrity of the tail boom and each individual component of the
tail is critical to maintaining controlled flight. Failure of the boom or of a major component of
the tail (i.e. the tail boom extension) will cause departure from controlled flight.
The hinge bolts with castle nuts and cotter pins should be removed every 100 hours and
remain on the 100 hour inspection list. These bolts undergo a large amount of stress, fatigue
and especially wear considering the installation. It would not be unlikely for the bolts OR the
cages (hinge brackets) to show significant wear. Immediate replacement of the hinge bolts or
brackets should be carried out at the first signs of significant wear. Note also that after several
replacements of the hinge brackets, the nutplate on the inside of the wing spar will be beyond
it’s life limit and will have to be replaced. This level of replacement can be done only by
removing or cutting the wing covers and should be scheduled to coincide with the replacement
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