Abstract: The article presents the problem of corrosion detection in the vertical stabilizer mounting plates of the MiG-29 aircraft. To ensure access to the examined surfaces, it was necessary to dismantle the vertical stabilizers. The authors presented a portion of the research results, demonstrated the research approach, and proposed improvements for future inspections, eliminating the need to dismantle the stabilizers.1. ORIGIN OF THE PROBLEM
In 2008, two Russian MiG-29 aircraft were involved in accidents. Examination of the wreckage proved that the cause was corrosion of the vertical stabilizer mounting plates, which led to structural weakening and, consequently, its destruction. Immediately after the cause was determined, flights of all Russian MiG-29 aircraft were suspended, and they were subjected to immediate inspection. After examining 291 aircraft, it turned out that over 30% were in need of repair[1].
2. RESEARCH
2.1. Preparation for research
The research was conducted to detect material thickness losses caused by corrosion (constrictions) and cracks located parallel to the plate surface (delaminations). The aircraft manufacturer provided guidelines on the inspection method.
Additionally, a reference sample was made from a fragment of the actual aircraft structure.
The sample consists of a duralumin stabilizer mounting plate and a riveted polymer composite skin reinforced with carbon fiber. On the plate, zones of reduced thickness were created through mechanical processing to simulate areas with varying degrees of corrosion. The minimum thickness reduction was 0.1 [mm]. Inspection of the sample based on the aircraft manufacturer’s recommendations confirmed the effectiveness of the imposed method in detecting corrosion losses.
ITWL has been conducting inspections of the composite part of the MiG-29 vertical stabilizer structure for many years [2]. These works are carried out in connection with the transition of these aircraft from service life-based operation to condition-based operation.
The composite checked during these tests is connected to the plate, but the methods used so far did not allow for the assessment of the plate’s condition. Radiographic examinations were also performed, obtaining very accurate images of the damage, but due to the geometry of the examined object, application on a real object would be extremely difficult to implement. (…)
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Source: Logistyka Magazine