Thursday, April 28, 2011

TYPES OF LIFTING TACKLE

Wire Rope

Wire rope is used in cranes, hoists, gantries and various types of sling.
Before use, the wire rope must be inspected for corrosion, wear, broken wires, etc.
The splices and their attachments must also be inspected for serviceability.
During use, care must be taken to ensure that the wire rope does not kink.
Before multi-legged wire rope slings are attached to a load, they must be carefully checked to ensure that the shackles are correctly attached and that the fittings are not twisted.

Chains

Chains are used in cranes and various types of sling especially when lifting cased engines, drums of fuel and oil etc, where strength is needed.
Before use, chains must be inspected for cracks, flaws, distortion, excessive wear and socketing.  Socketing is the name given to the grooves produced in the ends of the links when the links chafe against each other.  A 10% reduction in diameter of the chain material makes the chain unserviceable.

Fibre Rope

Slings of fibre rope are used for lifting propellers and must be inspected for frayed strands, pulled splices, excessive wear and deterioration.
When not in use the slings should be hung on pegs in a dry sheltered position.  Immediately before use, the strands should be slightly untwisted to ensure that they are not damaged, or mildewed internally.
A damaged or mildewed rope sling must be destroyed.

Aircraft Slings

These are provided to ease the handling, dismantling and assembly of aircraft components.  Only the correct type may be used.  The sling may be of the three‑legged type as used for aerofoils.  Other types of sling may be fitted with spreader bars or struts.
Some aircraft have special threaded holes in the airframe, which are used to attach the sling end fittings.  These holes are normally sealed with plugs.  An overhead crane, mobile crane or hoist is used to raise the loaded sling.

Saturday, April 23, 2011

Parking Overnight

If an aircraft has to be parked overnight or for longer periods in the open, then additional precautions should be taken to guard against ingress of foreign object damage (FOD) and the effects of adverse weather as follows:
  • The undercarriage ground locks must be fitted.
  • Pitot Tubes –small probes, which are open to external dynamic pressure, are covered.
  • Static vents -small holes in the fuselage, which are open to external static pressure, are covered.
  • Engine intakes are covered.
  • Engine exhausts are covered.
  • Cooling air intakes are covered.
In addition to the above and dependant on the prevailing climatic conditions of hot and cold it may also be necessary to fit additional covers such as cockpit covers and wheel covers.




































Blanks or covers are fitted to protect the aircraft from the ingress or taking in of:
  • Dirt
  • Birds
  • Insects
  • Rain
  • Snow
  • Slush
  • Ice
All orifices (holes) should be covered.

Blanks and covers for all the above components are specially designed for each particular aircraft and, if not visually obvious, are fitted with streamers to guard against their being left in position when the aircraft is prepared for service.

Servicing instructions should, however, include a pre-flight check to ensure that all covers and locks have been removed.

Thursday, April 21, 2011

Aircraft Parking



The terms Parking refer to leaving an aircraft out in the open,In a safe condition.
The conditions likely to be experienced over the duration of this period will depend on whether or not the aircraft is to be left in one of two conditions:
·         Brakes ‘on wheels chocked.
·         Brakes ‘on wheels chocked with additional tie-down security and covers fitted.
However, the minimum requirements should always relate to the prevailing or forecast wind-conditions, as the aircraft is of a streamlined shape with a large fin, designed to fly into the airflow.
On the ground, gusts of wind from varying directions may create a wind-vane damaging effect on the aircrafts structure therefore aircraft should be parked into the wind to prevent any incident .

When an aircraft is out of service and in the open, it should be secured against inadvertent movement and protected against adverse weather conditions.
The operations, which are recommended in the relevant Maintenance Manual, depend on the type of aircraft, the length of time it will be out of service and the prevailing or forecast weather conditions.
Between flights it is usually sufficient to apply the parking brakes, lock the control surfaces and chock the wheels, but even in a light wind light-aircraft must also be headed into wind and the wheels chocked front and rear.
Flying controls on many aircraft are locked by the movement of a lever in the cockpit/cabin, which is connected to locking pins at convenient positions in the control runs - the system of cables and levers connecting the pilot's controls to the control surfaces.
When this type of lock is not fitted, locking attachments may have to be fitted to the control column and rudder pedals.
A more positive method frequently used on light-aircraft, is the fitting of external control surface locks, which prevent control surface movement and thus prevent strain on the control system. 

All external locks should have streamers attached in order to make them clearly visible to make sure locks are engaged.