Composite materials are beginning to be used for the manufacture of aircraft fuselages thanks to their strength, lightness and rigidity, physical properties particularly suited to aircraft. However, after many flight cycles, composite materials must be examined and repaired to ensure integrity is maintained. As a result, flight engineers have developed a multi-step process to determine how composite materials in aircraft fuselages should be handled.
Step 1: Inspect the plane for damage
Original equipment manufacturers (OEMs) publish detailed guides regarding inspections and damage assessments. These guides are usually quite detailed and contain specific instructions for all aircraft operators on how to inspect their fleet, including the specific parts of the aircraft that they should monitor. If the investigation reveals signs of damage, another more detailed inspection is performed, which may include paint stripping, plug tests, or non-destructive testing (NDT) inspections.
Step 2: Remove damaged hardware
The next step in the process is to remove any damaged material. This includes removing a large area of paint to facilitate the repair. Past repair data usually tells engineers how much paint they need to get the plane airborne. Sanding is often the best method for removing paint and the use of paint strippers is not recommended.
Step 3: Prepare the repair area and materials
After removing enough paint from the plane, engineers are then tasked with preparing the area to be repaired and gathering the materials needed to begin the procedure. Aircraft preparation is often dependent on the OEM manual, but may include mechanical abrasion of the area to increase molecular activity, which should ensure a stronger chemical bond between the repair material and the original fuselage area . The process for collecting repair materials varies from OEM to OEM and is not standardized due to the different procedures prescribed by each manufacturer. However, it may involve the incorporation of resin into the tissue used for the repair.
Step 4: Repair the plane
The type of repair required depends on the requirements described in the OEM manual. An example of a repair technique is the bonded repair, which basically involves tapering the repair area around the damaged area of the aircraft exterior and adhesively bonding a composite repair patch to that area. It is generally used on aircraft with thin skins bonded to a honeycomb or foam core. Nevertheless, other repair methods are also used, but ultimately it is recommended that engineers simply follow OEM guidelines when repairing the aircraft for safety reasons.
Step 5: final inspection
After attending to the repair of the aircraft, aircraft operators must then inspect the exterior of the aircraft to ensure that there is proper curing of the resin and that the bond between the aircraft and repair material is complete. Other criteria may be listed in the OEM manual. Strict adherence to the protocols set by the OEM is absolutely necessary to ensure the safety and integrity of the aircraft.