C42E 540kg LSA POH Issue 3 China
15.03.2016
Page 24 of 36
7
DESCRIPTION OF AIRPLANE AND SYSTEMS
The C42 E is a simple aircraft whose structures and systems are readily inspected and maintained.
However, since some of its systems differ from those found on conventional aircraft; this section should
be studied before dismantling, repair or inspection.
7.1
Airframe
Fuselage
A 165 mm diameter aluminium tube runs from nose to tail and carries all the major assemblies: engine,
seats, undercarriage, fuel tank, and tail empennage. The cockpit structure, consisting of a thin walled
aluminium tube frame, includes a welded aluminium box-section frame at its top to which the wing spars’
roots attach, and which provides compression load carry-through for both spars.
The composite seats are supported around their edges by attachment to the cockpit frame. Around the
outboard edges of the seats, some of these loads are passed via the composite lower fairing to a lateral
beam consisting of a 56mm reinforced box section. The ends of this beam accommodate the wing struts
and withstand tension loads from them.
All load carrying (structural) members of the airframe are aluminium alloy tubes; most of which terminate
in spherical bearings.
Wing
The wing has a ladder construction comprising leading and trailing edge tubes, connected by compression
struts at intervals along its span. The triangulated wing struts, terminating at a fixed point at the top of
the undercarriage, brace the wing against fore and aft loads. In g flight these struts are under
tension.
In +g flight both leading and trailing edge tubes inboard of the wing struts junctions, experience
compression loads from the wing struts, as well as direct bending from lift loads.
The wing, tail empennage and all control surfaces are constructed of thin walled aluminium tubing. They
are covered by a reinforced polyester fabric, sewn into complete envelopes and fitting tightly over their
frames.
Undercarriage
The tricycle undercarriage has suspension on all wheels and damping on the main wheels. The front fork
is directly connected to the rudder pedals. Hydraulic disc brakes operate on the main wheels only.
Main wheels’ suspension stiffness can be adjusted by varying the air pressure in the damper units via the
valves in their casings. A special high pressure pump is required for this purpose.
7.2
Control Systems
Pitch
A central control stick, accessible by both occupants, is located over the fuselage between the seats.
Fore and aft movement of this stick is transferred, via longitudinal push tubes, to a motion reversal lever
installed midway between the cockpit and tail. This installation also accommodates the pitch stops. A
second push tube, of similar length, runs from this lever to the elevator horn. A rearward movement of the
stick lifts the elevator; forward movement depresses it.
Each push rod terminates in a spherical bearing (Rose joint) maintaining loads through the centres of the
tubes. The threaded roots of these fittings can be susceptible to failure if bending loads are applied; it is
important to ensure complete freedom of the joints at extremes of their movements, such that bending
loads cannot be applied.
