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Fabric Covering, Essay Example
Fabric-covered aircraft have a significant place in aviation history. Initially, a fabric-covered wood frame was employed in constructing the renowned Wright Flyer, and many other aircraft designers and builders used fabric covering throughout the first decades of production aircraft. One major benefit of fabric covering on an airplane is its reduced weight. Since recovering a fabric aircraft involves a significant repair or alteration, an IA must be involved in the process (Ren 62). Therefore, the IA should be involved from the start and at key points throughout the process to ensure the work proceeds as needed.
Modern fabric coverings endure forever; thus, the recovery process is a unique chance to evaluate the aircraft. Before the new fabric is placed, inspectors and owner-operators ought to take advantage of this chance to inspect the aircraft comprehensively. Regarding strength and durability, the fabric attachment technique should be the same as that employed by the manufacturer of the recovered or repaired aircraft. Carefully remove the old fabric from the airframe, noting any inspection covers, drain grommets, or connection methods. Before starting the covering process, a decision must be taken on the fabric covering method—either the envelope approach or the blanket method is suitable.
The blanket method of re-covering involves trimming and fastening numerous flat sheets of fabric to the airframe. As it comes off the bolt, the certified greige polyester fabric can be up to 70 inches wide and utilized to cover an airplane (Czaban). The size and configuration of the blankets required to cover each aircraft must be determined separately. It is typical to make a single blanket cut for each tiny surface. Two blankets that overlap may be necessary for wings. Multiple blankets between the main structural sections are placed over the fuselages, with the bottom frequently receiving just one blanket. It might take more than two blankets to completely cover the top and bottom surfaces of really large wings (Czaban). In every instance, the fabric is attached to the airframe using authorized adhesives and following the necessary covering process guidelines.
The envelope method, an alternative to re-covering, saves time by employing fabric envelopes that have been precut and sewed to cover the aircraft. The edge distance, fabric fold, and machine sewing thread used to sew the envelopes must all be authorized. Each main surface, including the fuselage and wings, may be covered with a single, form-fitting envelope thanks to the creation of patterns and the cutting, sewing, and finishing of cloth. Envelopes are adhered to the airframe using adhesive after being slid into place, oriented with the seams in the right place, and cut to fit. Depending on the airframe architecture, envelope seams are typically found over the airframe’s structural elements at discrete locations such as the trailing edge structures and the top and bottom of the fuselage.
Recovering a fabric airplane requires careful planning. Initially, put together the supplies and equipment needed to finish the operation. A materials and tool list is often provided by the STC holder, either individually or in the STC manual. The workplace requires regulation of ventilation, humidity, and temperature. For most re-covering goods, additives are available that make up for the absence of perfect environmental conditions (Czaban). While the job is done, simple, alternating access to the top and lower surfaces is made possible by rotating work stands for the fuselage and wings. They can be utilized alone or in conjunction with sawhorses to support the aircraft structure during working. Additionally advised are a rolling cart, a storage cabinet, a workbench, or a table.
Most re-covering techniques include the use of numerous highly harmful materials. Appropriately protection must be applied to prevent serious short- and long-term adverse health effects. A suitable respirator, eye protection, and skin protection are essential. Nitrate dope is highly flammable, as was already established. When handling this and other covering process materials, enough ventilation and a fire extinguisher with the appropriate rating should be nearby (Silver 87). It might be necessary to ground the workspace to avoid static charge buildup. All methods for re-covering cloth require spraying the fabric surface with repeated applications of various materials. It is advised to use a high-volume, low-pressure (HVLP) sprayer. All procedures require effective ventilation.
An aircraft fabric covering replacement process begins with removing the previous covering. Next, remove the old fabric from the airframe using razor blades or a utility knife. To prevent harm to the airframe, caution should be used. The exposed airframe structure needs to be properly cleaned and inspected after removing the old fabric. This stage of the procedure should engage the IA working on the project. The manufacturer’s instructions, the STC, or AC 43.13-1 should be followed regarding the inspection’s specifics. A solvent, such as MEK, must be used to remove all of the old glue from the airframe. Several components may be chosen to be removed for cleaning, inspection, and testing after a comprehensive inspection has been completed. It is now necessary to do any repairs, including eliminating and treating all corrosion. If the airframe comprises steel tubing, many technicians take this chance to grit blast the entire thing.
A wing’s leading edge is a crucial location where airflow diverges and starts to flow laminarly over the surfaces of the wing, producing lift. It is advantageous to have a uniform, smooth surface here. Leading edges of plywood need to be sanded until smooth, raw wood is visible. If there are any oil or grease stains, they must be removed using naphtha or one of the other cleansers listed. If any chips, indentations, or inconsistencies exist, they can be filled with an authorized filler and smoothed off with sandpaper (Silver 86). Aluminum wings with leading edges covered in the fabric may have a sheet of felt or polyester padding placed before the cloth is put to achieve a smooth finish.
The airframe should be properly cleaned, examined, and mended before varnish or certified primer is used if the structure is made of wood. This process is also known as “dope proofing.” Acid etching must be done first on exposed metal. Then, utilize the item(s) recommended by the manufacturer or in the STC to prime the metal. Typically, two-part epoxy primers and varnishes are specified because they are resistant to the effects of the fabric adhesive and subsequent coatings (Ci??ak 103). Zinc chromate and spar varnish are examples of one-part primers that are normally unacceptable. The chemicals destroy the adhesive primers, resulting in a loss of fabric-to-airframe adhesion. Anti-chafe tape should be used to cover any sharp edges, metal seams, rivet heads, or other components of the aircraft structure that could cut or wear through the fabric.
Inexperienced technicians are urged to build a test panel to experiment with the fabric and other materials and methods before using them on the aircraft. Smaller surfaces like the control and empennage are frequently advised to be covered initially. These mistakes can be fixed and are less expensive if they do happen. All surfaces, including the wings and fuselage, are treated using the same methods. Once dexterity has been demonstrated, the order in which one moves on is frequently a matter of personal preference.
Ci??ak, Patryk, et al. “Corrosion problems of the metalized connection of the aircraft fabric covering–selected problems.” Journal of KONBiN 51.4 (2021): 91-105.
Czaban, Magdalena. “Aircraft corrosion–review of corrosion processes and its effects in selected cases.” Fatigue of Aircraft Structures (2018).
Laroche, Alexandre, et al. “Durability of superamphiphobic polyester fabrics in simulated aerodynamic icing conditions.” Coatings 10.11 (2020): 1058.
Ren, Guina, et al. “A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.” Journal of colloid and interface science 522 (2018): 57-62.
Silver, Richard M. “Was Paul Klee’s scleroderma an occupational disease? A series of historical and clinical vignettes, part III.” Journal of Scleroderma and Related Disorders 5.2 (2020): 85-89.