This report presents the findings of literature review and an experimental programme conducted on the effects of surface treatments of large commercial aircraft landing gear components on fatigue performance. The review and experimental programme have been carried out in response to the safety recommendations contained within the Air Accident Report No. 1/97 (EW/C95/4/2). This investigated the failure of MD-83 aircraft’s main landing gear outer cylinder. Failure was considered to be due to the presence of small fatigue cracks. The origin of which were associated with features believed to have been produced by grit blasting operation used to prepare the surface after shot peening for cadmium plating treatment.
The literature review concentrates on the three surface treatments of shot peening, grit blasting and cadmium plating as these are considered to potentially have the greatest influence on fatigue life. The shot peening operation has number of beneficial effects due to the introduction of compressive residual stress layer at the component surface. The grit blasting operation is carried out to remove the passive layer found at the surface of ultra high strength steel alloys used in the manufacture of landing gear components. This enhances the adhesion of cadmium during the plating operation. However, the grit blasting process also roughens the surface and leaves embedded grit particles within the surface layer. This may reduce the fatigue resistance of the component. Cadmium plating operations are carried out to give corrosion protection to ultra high strength steel landing gear components. Careful control of the plating process is required in order to reduce the risk of embrittlement caused by hydrogen absorption associated with the cleaning and plating procedure.
The literature review concentrates on the three surface treatments of shot peening, grit blasting and cadmium plating as these are considered to potentially have the greatest influence on fatigue life. The shot peening operation has number of beneficial effects due to the introduction of compressive residual stress layer at the component surface. The grit blasting operation is carried out to remove the passive layer found at the surface of ultra high strength steel alloys used in the manufacture of landing gear components. This enhances the adhesion of cadmium during the plating operation. However, the grit blasting process also roughens the surface and leaves embedded grit particles within the surface layer. This may reduce the fatigue resistance of the component. Cadmium plating operations are carried out to give corrosion protection to ultra high strength steel landing gear components. Careful control of the plating process is required in order to reduce the risk of embrittlement caused by hydrogen absorption associated with the cleaning and plating procedure.
- Status:
- Current
- Review comment:
- -
- Version:
- 1
- Version date:
- 28-Jul-2022
- View file:
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