Bucher Leichtbau uses HBM test and measurement technology to test airworthiness of galleys
Food on board an aircraft is to be light and easily digestible. Being lightweight is a requirement for the kitchens on board (called galleys), too - and nonetheless they need to be able to withstand large physical loads. Bucher Leichtbau AG, Switzerland, is a leading manufacturer of galleys and cabinets installed in passenger aircraft and therefore places its trust in stringent testing of its modules to ensure their airworthiness. In the test bench on board: The complete measurement chain from HBM.
Technologies and systems used in the aircraft industry need to comply with stringent rules and regulations. Special evidence regarding statics is required to prove the airworthiness of aircraft cabin installations. This also applies to the galleys used on board.
Conditions on board are particularly tough for the galleys. To ensure maximum efficiency, galley modules need to be extremely lightweight - and, on the other hand, must withstand extreme loading.
Lightweight design built to withstand the forces of gravity
Bucher Leichtbau AG
Lightweight design built to counteract the forces of gravity to the extent possible - Bucher Leichtbau, with production sites in Switzerland and the USA, is a master in this field.
Bucher Leichtbau develops and produces innovative lightweight solutions for civil aviation, air rescue and the automotive industry. The range of products comprises different fields of application, such as catering, cabin, emergency medical systems and automotive / VIP. Galleys and cabinets from Bucher Leichtbau are the ones most often used in civil aviation.
Such combined modules, also called "monument", can carry a net load of eight times their tare weight and have to withstand accelerations up to 9 times the acceleration due to gravity (9g).
Maintenance costs remain very low over the years because of the modular and rugged design. The required minimal service life is 25 years. However, galleys and closets need to prove their airworthiness prior to their first take-off.
A distinction is made between flight loads (regular flight loading conditions such as take-off, landing, turbulences, etc.) and emergency landing loads (controlled emergency landing or aborted take-off). Each of these loads is simulated on ground test facilities first. The galleys and cabinets are subjected to any occurring forces and accelerations (including the safety reserve) and their behavior under these loads is tested. Only after having successfully passed these tests will the monuments be approved for installation in aircraft by authorities, aircraft manufacturers or end customers (airlines).
Complex test bench simulates forces occurring during operation
A test bench is built up for simulating the forces occurring during operation (its design depends on the type of aircraft and requirements). (Tensile) force is applied to the test object in the test bench via a central 500 kN hydraulic cylinder; its force is distributed between the individual components of the test object using a complex system of wire ropes, chains and so-called "whiffles" (whiffle trees).
In the past, (tensile) force applied to the test bench was determined by converting the measured pressure of the hydraulic cylinder. This was the only indicator of monument loading. Further load values on individual components were computed on the basis of the distribution of forces resulting from the length of the whiffle branches.
Taking measurements instead of calculating
U10M precision force transducer ensures safety
Bucher Leichtbau has placed its trust in measurement technology from HBM for several years now, because it offers enhanced precision and efficiency. The force applied to the overall system via the central hydraulic cylinder is measured using a precision force transducer from the U10M family that is connected in series.
Furthermore, additional, smaller force transducers from the U9B family are used to measure the actually occurring forces directly on the component in areas subjected to particular loads or areas of special interest, for example, doors, locks, bolts, consoles, fittings, etc.
Galley deformation is measured using inductive displacement transducers in critical areas. All measurement data is synchronously transmitted to a data acquisition system (Spider8 or QuantumX) using catman®Easy software for processing, visualization, analysis and storage.
Acquisition of measurement data is thus very reliable and precise and analyses can conveniently be copied to a corresponding report. The manufacturer or end customer (airline) approves and confirms the documented tests prior to installation in the aircraft.
The sophisticated concept and the use of precision transducers guarantee that the objects under test withstand the forces and accelerations occurring during operation.
"Using the precise U10M force transducer permits us to determine the loads acting on our galleys in a significantly better and more efficient way. This enables us to provide our customers with very reliable statements on the airworthiness of galleys from Bucher Leichtbau AG"
Thomas Blum, Deputy of Certification Manager, Bucher Leichtbau AG