Southern Airframe Specialists structures repair

Airframe structures repair by

Southern Airframe Specialists Ltd

Unit 2 Ash Park Business Centre

Ash Lane, Little London

Hampshire. RG26 5FL

Tel / Fax :01256 883333 - Mobile 07962 014869

Email : paul.allen@southernairframes.com

Sheet metal structural repair is specialist work subject to c20 structures repair approval because of the effects of cut-outs (as aircraft doors and hatches are known).

Doors, windows and hatches are a major problem in the design of the aircraft, because they interrupt the load-bearing structure of the fuselage. Windows, being small, do not create a severe problem, and the structure around them is reinforced, with windows themselves not considered to support any fuselage loads. Doors may or may not carry some of the load in the fuselage structure, depending on their design. With passenger doors, it is necessary to be able to open them quickly and easily, and this restricts the load they are permitted to carry because they must not jam closed in a crash. The structure around the door is therefore designed to carry tensile and shear loads around the door aperture, and of course to pick up the loads, mainly pressure loads, on the door itself. Many doors are designed to fit from the inside, so that the pressure loads act to hold the door closed, and the failure of latching mechanisms becomes less likely and less critical.

Door and hatch repair c4 approval.

Aircraft freight doors present particular problems. Their size often dictates that they cannot be opened inwards, so satisfying the need for fail-safety is more complex. A mechanism is incorporated to prevent pressurisation of'the aircraft unless the door is closed and, fully locked. With doors of this size, the cut-out from the fuselage is so large that the door must carry some of the fuselage loads when closed.

Normally structural aircraft freight doors carry a proportion of the fuselage loads, reducing the loads carried by the adjacent structure. However, additional structure in the door region will still be required, or stresses will be higher than in a corresponding section without a cut-out. With a large top-hinged freight door, the hoop tension is transmitted through the hinges, through the door and out through latches at the bottom of the door.

The loads arising from large doors may become critical on the ground, when the door is open. In this case, the aerodynamic loads arising from the wind on the large surface area of the door generate large forces in the hinges and the door struts.

Flap and slat repair.

Most aircraft need to land as slowly as possible, for safety. Providing enough lift to support the aircraft in flight at very low speeds would require a design that would not be efficient at the higher speeds at which most aircraft cruise. So extra devices are added to the leading and trailing edges of most aircraft to increase lift when deployed. Other devices may be deployed to reduce the lift produced by the wing, to allow a steeper approach or provide a positive touchdown.

Flaps and slats are fitted at the trailing edges, and attached to the rear spar and/or the auxiliary spar. There are several different types of flap, of varying degrees of complexity and effectiveness. Light aircraft will usually have simple flaps, if any. Larger aircraft have the more complex split flap or Fowler flap. Most large transport aircraft have double-slotted Fowler flaps. Leading-edge flaps, called slats, may be added to increase lift even further. They are often fitted to combat aircraft, where the very small wing needed for good high-speed performance is highly unsuited to providing lift at low speeds for take-off and landing. When extended, many slats leave a gap or slot between the slat and the leading edge. This gap allows air to flow through and helps the airflow to stay attached to the wing surface, reducing the tendency for the wing to stall. Flaps and slats increase both lift and drag. and both are an advantage for landing. When the aircraft spped is higher, they are not needed and are retracted out of the airflow. So much mechanical working of critical structures requires careful maintenance, so aileron repair, flap and slat repair, structural sheet metal work are important work.